Portal 2 developer commentary: Difference between revisions

Line 1:

'''''[[Portal 2]]'' [[developer commentary]]'''.

== Commentary ==

== Singleplayer Commentary ==

=== Welcome To Portal 2 ===

{{Quotation | Gabe Newell, Container Ride

Line 205:

{{Quotation | Gautam Babbar

| Our initial goal in designing the hub was to provide players with a lot of choices, so they could to sample a variety of game types. The idea was that if they got stuck or needed a break, they could pick another test chamber or another mechanic to explore. In reality, this prevented us from doing sufficient training and limited the overall scope of the puzzles. With such a flat structure, it was much harder to layer old mechanics onto new ones, because we couldn't guarantee that players understood what they needed to know to solve a puzzle. By going linear, we could guarantee prior knowledge and provide a much better experience, more satisfying pacing and a story that gathered momentum over a long period of time.

}}

~~=== Stealing The Core ===~~

~~{{Quotation | Ted Backman~~

| We have a taunt where one robot steals the other's core. When implemented, it was the only taunt that required one person to initiate. Because of this we were afraid that it would be used for griefing. We were in the process of rethinking our approach when early playtesters rated this as their favorite taunt. It was also the most used team taunt because it only required one player to initiate, and was easier to use than the others. We ended up changing all the other team taunts to emulate the way stealing the core works.

}}

~~=== Ping Tool ===~~

~~{{Quotation | Josh Weier~~

| Early on we realized that trying to tell your partner where to go, where to look or where to place a portal was going to be really hard. Even with voice chat, saying 'over there' doesn't give enough information to your partner within the 3D space. Players kept wanting to get up and point directly at their partner's screen. We developed the ping tool to address this problem. Because the ping tool was so important, we decided to train players in its use before we did anything else. We held back on the vast majority of player actions and let the players focus entirely on the ping tool. This is why the co-op bots start separated in a tube, without even the ability to walk or shoot a portal.

}}

~~=== Ping Context ===~~

~~{{Quotation | Iestyn Bleasdale-Shepherd~~

| Most players don't realize that the ping tool is context sensitive. When they are playing voice enabled, players usually rely on the look portion of the ping tool. Without voice, icons such as 'press the button' or 'stand here' become much more important.

}}

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{{Quotation | Brian Jacobson

| It is important to give co-op players a way to coordinate their action. Seeing how our players naturally wanted this ability, we decided to support it with the ping timer, and ended up designing some puzzles around it. Due to lag and other issues, syncing up actions over voice chat turned out to be rather difficult. Therefore we created the countdown timer as a way for players to keep in sync. It's completely predictable. Both players see the GO at the same instant, and the clocks run in sync even if they are on different systems.

}}

~~=== Hand Off ===~~

~~{{Quotation | Chris Boyd~~

| Something that really surprised us was how often playtesters stated that they loved the basic experience of handing off a cube to their partner. Players didn't expect such a fundamental physical interaction to just work in a game. Before trying it for the first time, they would discuss their plan as if it were some unique or special new game mechanic. When it just worked, they were overjoyed.

}}

~~=== Dying All The Time ===~~

~~{{Quotation | Andrea Wicklund~~

| Normally in games, when players die, they see this as a big failure. But in Portal, death is a normal part of the puzzle solving experience. In co-op, death not only happens more frequently, but it can happen at the hands of your partner (purely accidentally of course). We felt it was important to not only make death "no big deal," but to make it fun. Early on, we tried some elaborate death animations--such as showing your robot slowly getting crushed under a giant crusher. These were awesome to watch, but they quickly became repetitive. Also, after a very short while, players grew afraid to take risks. The fear of having to wait a long time before trying again prevented them from simply playing and experimenting in a spirit of fun. We had to find the right balance where death was quick enough to be a non-penalty, and elaborate enough to be visceral and satisfying--a fun pay-off for creative play.

}}

Line 240:

Line 215:

{{Quotation | Danika Wright

| Since the co-op characters can die at any time, we needed a way to rebuild them quickly and often. Therefore in co-op, we replaced the elevators that connected test chambers in singleplayer, with disassembly machines. These are meant to reinforce the idea that since the robots are disposable, being destroyed is no big deal. In the robot world, it happens all the time!

}}

~~=== Airlocks ===~~

~~{{Quotation | Garret Rickey~~

| Airlocks were introduced mainly as a way to allow players to focus on individual puzzles. In some of our early investigations, areas contained puzzles that were meant to be solved as a group, as well as others that were for individual solution. But we found that if players could move freely between them, they logically assumed that the individual puzzles were part of one big puzzle. This had bad results. For clarity, we created these airlock-like spawn rooms that act as checkpoints between puzzles. Once both players enter the airlock, we lock off access.

}}

~~=== World Imposters ===~~

~~{{Quotation | Gary McTaggart~~

| In Left 4 Dead 2, we authored simple, fogged, black versions of the world as monolithic models to avoid the CPU overhead of rendering the world again for water reflections. This worked well for the Left 4 Dead 2 outdoor environments where most light comes from the sky. But Portal 2 is almost entirely indoors, so the color and value of the world geometry is apparent in the water reflections. Since the Portal 2 world geometry is relatively simple, we automatically build a version of the world geometry that has a single texture that combines both lighting and surface shading along with another texture with just surface shading. The latter texture is used when rendering dynamic lights. These textures are at the same spatial resolution as the light maps and get packed into a single large atlased texture per level. Drawing this simple world imposter model takes very little CPU time, which was a limited resource on Portal 2 due to the many portal views, split-screen views, and water reflection views that we needed to render. We initially planned on using the world imposters only for water reflection rendering, but we ended up using it to improve performance in split-screen mode where it is used for rendering distant portals and portals that are two levels deep. We also use the world imposters to render water in full screen co-op mode, to give us some performance overhead, since the co-op mode has more portal views to render than single-player mode.

}}

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{{Quotation | David Feise, Three Gels

| With the gel sounds for Portal 2 we wanted to create something whimsical that would add to the player’s enjoyment of the mechanics, without crossing over the line into ludicrousness. For example, our initial pass at the blue gel 'bounce' sound included a rubber playground ball, a pitch-bent harp string and a processed mouth harp. The resulting sound captured the idea of fun, but was off the charts on the goofy scale. After several iterations we settled on the current, less over-the-top sound which features a piece of metal bar bouncing like a diving board and a heavy dose of synthesis. It’s not as wacky, but hopefully it’s still fun.

}}

~~=== Gesture Wheel ===~~

~~{{Quotation | Andrew Burke~~

| In our first implementation, gestures were automatically selected based on the player's context. For example, Blue might do a special gesture when standing on a floor button. Players became bored of seeing these gestures so quickly that they stopped using them before discovering any of the special contexts. Because of this, we decided to give players control of gestures as a way to express themselves, but when shown the full set from the start, they were overwhelmed by all the choices. By awarding gestures as the game progresses, we allow players to familiarize themselves with each gesture in turn. Leaving visible empty slots in the gesture wheel lets players anticipate that they'll be rewarded with cool new gestures as they progress. The gesture wheel provides quick access so that players can feel comfortable tossing out a gesture during down time, letting them pick the perfect moment to share a high five.

}}

~~=== High-Five ===~~

~~{{Quotation | Matthew Scott~~

| We noticed that after playtesters had solved a difficult puzzle together, they'd sometimes pause before funneling through the exit door to repeatedly jump up and down in excitement. We realized that these meeting points would be the perfect time to allow players to high-five each other and celebrate their victory in style. Our first interface attempt had one player initiate a high five by holding their hand up and waiting, the other player could join in by selecting the same gesture. If they were standing in the correct positions relative to each other, they would pull off a high five. But learning the correct places to stand was too difficult. So we decided to automatically move the bots into the correct positions for the high five. Sometimes, however, the player who wanted to high five would be left hanging as the other player ran ahead without accepting. Increasing the time that the initiator waited with his hand up gave the other player time to return and accept, but being frozen in place for more than a few seconds was too frustrating. So finally, we made players auto-accept the team gestures. Now, when the mood strikes either player, the game always ensures a successful celebration.

}}

Line 375:

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{{Quotation | Jeep Barnett

| This puzzle requires one of Portal’s trickiest logical leaps. Early playtesters often took longer than their patience would allow, and were nearly ripping out their hair by the time they’d finally solved it. But almost everyone insisted that the payoff was by far their favorite moment in all of co-op. We significantly reduced the average solution time by adding a puzzle just before this where two cubes repeatedly collide, but this almost completely robbed the appeal from what was once a high moment. So, instead we decided to make a few subtle adjustments and leave players with the responsibility to make the final leap. First we added a puzzle four chambers earlier, to teach players to fling by cutting their hard light bridge and falling into a surface directly below. We then subconsciously prime the thought of midair collision by having players repeatedly ricochet weighted spheres against a hard light bridge. Finally, we designed this room’s layout, lighting, and decals so that players would see the entire space as a symmetrical whole and visualize the bots' fling path. By planting shards of the idea in their heads, we allow players to own that exciting dual collision epiphany while keeping their sanity intact.

}}

~~=== Trust Puzzles ===~~

~~{{Quotation | Eric Tams~~

| Several puzzles in the game require the players to take on distinct, intertwined roles. We called these asymmetric chambers 'Trust Puzzles,' because one player is often placing their life in the hands of the other. When one player accidentally kills the other it almost always ends in laughter. So much laughter, that we sometimes had to question if it really was a legitimate accident. These puzzles also require players to stay in constant communication, which naturally leads to some great moments of cooperative bonding. While some teams found these stressful, for many partners, these puzzles were their favorite type. But everyone agreed that they added needed variety and a nice change of pace. And by swapping roles, each player can get an entirely different experience within the exact same puzzle.

}}

Line 445:

Line 395:

* SSH backdoor for updates and monitoring (possible to watch exactly what people were seeing as they dialed in)

* Combined might of internets is terrifying

}}

==Co-op commentary==

1. Confidence Building; {{code|mp_coop_catapult_1}}

=== Gesture Wheel ===

{{Quotation | Andrew Burke

| In our first implementation, gestures were automatically selected based on the player's context. For example, Blue might do a special gesture when standing on a floor button. Players became bored of seeing these gestures so quickly that they stopped using them before discovering any of the special contexts. Because of this, we decided to give players control of gestures as a way to express themselves, but when shown the full set from the start, they were overwhelmed by all the choices. By awarding gestures as the game progresses, we allow players to familiarize themselves with each gesture in turn. Leaving visible empty slots in the gesture wheel lets players anticipate that they'll be rewarded with cool new gestures as they progress. The gesture wheel provides quick access so that players can feel comfortable tossing out a gesture during down time, letting them pick the perfect moment to share a high five.

}}

=== Stealing The Core ===

{{Quotation | Ted Backman

| We have a taunt where one robot steals the other's core. When implemented, it was the only taunt that required one person to initiate. Because of this we were afraid that it would be used for griefing. We were in the process of rethinking our approach when early playtesters rated this as their favorite taunt. It was also the most used team taunt because it only required one player to initiate, and was easier to use than the others. We ended up changing all the other team taunts to emulate the way stealing the core works.

}}

=== Airlocks ===

{{Quotation | Garret Rickey

| Airlocks were introduced mainly as a way to allow players to focus on individual puzzles. In some of our early investigations, areas contained puzzles that were meant to be solved as a group, as well as others that were for individual solution. But we found that if players could move freely between them, they logically assumed that the individual puzzles were part of one big puzzle. This had bad results. For clarity, we created these airlock-like spawn rooms that act as checkpoints between puzzles. Once both players enter the airlock, we lock off access.

}}

=== World Imposters ===

{{Quotation | Gary McTaggart

| In Left 4 Dead 2, we authored simple, fogged, black versions of the world as monolithic models to avoid the CPU overhead of rendering the world again for water reflections. This worked well for the Left 4 Dead 2 outdoor environments where most light comes from the sky. But Portal 2 is almost entirely indoors, so the color and value of the world geometry is apparent in the water reflections. Since the Portal 2 world geometry is relatively simple, we automatically build a version of the world geometry that has a single texture that combines both lighting and surface shading along with another texture with just surface shading. The latter texture is used when rendering dynamic lights. These textures are at the same spatial resolution as the light maps and get packed into a single large atlased texture per level. Drawing this simple world imposter model takes very little CPU time, which was a limited resource on Portal 2 due to the many portal views, split-screen views, and water reflection views that we needed to render. We initially planned on using the world imposters only for water reflection rendering, but we ended up using it to improve performance in split-screen mode where it is used for rendering distant portals and portals that are two levels deep. We also use the world imposters to render water in full screen co-op mode, to give us some performance overhead, since the co-op mode has more portal views to render than single-player mode.

}}

=== Dying All The Time ===

{{Quotation | Andrea Wicklund

| Normally in games, when players die, they see this as a big failure. But in Portal, death is a normal part of the puzzle solving experience. In co-op, death not only happens more frequently, but it can happen at the hands of your partner (purely accidentally of course). We felt it was important to not only make death "no big deal," but to make it fun. Early on, we tried some elaborate death animations--such as showing your robot slowly getting crushed under a giant crusher. These were awesome to watch, but they quickly became repetitive. Also, after a very short while, players grew afraid to take risks. The fear of having to wait a long time before trying again prevented them from simply playing and experimenting in a spirit of fun. We had to find the right balance where death was quick enough to be a non-penalty, and elaborate enough to be visceral and satisfying--a fun pay-off for creative play.

}}

=== High-Five ===

{{Quotation | Matthew Scott

| We noticed that after playtesters had solved a difficult puzzle together, they'd sometimes pause before funneling through the exit door to repeatedly jump up and down in excitement. We realized that these meeting points would be the perfect time to allow players to high-five each other and celebrate their victory in style. Our first interface attempt had one player initiate a high five by holding their hand up and waiting, the other player could join in by selecting the same gesture. If they were standing in the correct positions relative to each other, they would pull off a high five. But learning the correct places to stand was too difficult. So we decided to automatically move the bots into the correct positions for the high five. Sometimes, however, the player who wanted to high five would be left hanging as the other player ran ahead without accepting. Increasing the time that the initiator waited with his hand up gave the other player time to return and accept, but being frozen in place for more than a few seconds was too frustrating. So finally, we made players auto-accept the team gestures. Now, when the mood strikes either player, the game always ensures a successful celebration.

}}

=== Hand Off ===

{{Quotation | Chris Boyd

| Something that really surprised us was how often playtesters stated that they loved the basic experience of handing off a cube to their partner. Players didn't expect such a fundamental physical interaction to just work in a game. Before trying it for the first time, they would discuss their plan as if it were some unique or special new game mechanic. When it just worked, they were overjoyed.

}}

=== Ping Tool ===

{{Quotation | Josh Weier

| Early on we realized that trying to tell your partner where to go, where to look or where to place a portal was going to be really hard. Even with voice chat, saying 'over there' doesn't give enough information to your partner within the 3D space. Players kept wanting to get up and point directly at their partner's screen. We developed the ping tool to address this problem. Because the ping tool was so important, we decided to train players in its use before we did anything else. We held back on the vast majority of player actions and let the players focus entirely on the ping tool. This is why the co-op bots start separated in a tube, without even the ability to walk or shoot a portal.

}}

=== Trust Puzzles ===

{{Quotation | Eric Tams

| Several puzzles in the game require the players to take on distinct, intertwined roles. We called these asymmetric chambers 'Trust Puzzles,' because one player is often placing their life in the hands of the other. When one player accidentally kills the other it almost always ends in laughter. So much laughter, that we sometimes had to question if it really was a legitimate accident. These puzzles also require players to stay in constant communication, which naturally leads to some great moments of cooperative bonding. While some teams found these stressful, for many partners, these puzzles were their favorite type. But everyone agreed that they added needed variety and a nice change of pace. And by swapping roles, each player can get an entirely different experience within the exact same puzzle.

}}

=== Ping Context ===

{{Quotation | Iestyn Bleasdale-Shepherd

| Most players don't realize that the ping tool is context sensitive. When they are playing voice enabled, players usually rely on the look portion of the ping tool. Without voice, icons such as 'press the button' or 'stand here' become much more important.

}}

@@ Line 1: / Line 1: @@
 '''''[[Portal 2]]'' [[developer commentary]]'''.
-== Commentary ==
+== Singleplayer Commentary ==
 === Welcome To Portal 2 ===
 {{Quotation | Gabe Newell, Container Ride
@@ Line 205: / Line 205: @@
 {{Quotation | Gautam Babbar
 | Our initial goal in designing the hub was to provide players with a lot of choices, so they could to sample a variety of game types.  The idea was that if they got stuck or needed a break, they could pick another test chamber or another mechanic to explore.  In reality, this prevented us from doing sufficient training and limited the overall scope of the puzzles.  With such a flat structure, it was much harder to layer old mechanics onto new ones, because we couldn't guarantee that players understood what they needed to know to solve a puzzle.  By going linear, we could guarantee prior knowledge and provide a much better experience, more satisfying pacing and a story that gathered momentum over a long period of time.
-}}
-=== Stealing The Core ===
-{{Quotation | Ted Backman
-| We have a taunt where one robot steals the other's core. When implemented, it was the only taunt that required one person to initiate. Because of this we were afraid that it would be used for griefing. We were in the process of rethinking our approach when early playtesters rated this as their favorite taunt.  It was also the most used team taunt because it only required one player to initiate, and was easier to use than the others.  We ended up changing all the other team taunts to emulate the way stealing the core works.
-}}
-=== Ping Tool ===
-{{Quotation | Josh Weier
-| Early on we realized that trying to tell your partner where to go, where to look or where to place a portal was going to be really hard.  Even with voice chat, saying 'over there' doesn't give enough information to your partner within the 3D space.  Players kept wanting to get up and point directly at their partner's screen.  We developed the ping tool to address this problem.  Because the ping tool was so important, we decided to train players in its use before we did anything else.  We held back on the vast majority of player actions and let the players focus entirely on the ping tool.  This is why the co-op bots start separated in a tube, without even the ability to walk or shoot a portal.
-}}
-=== Ping Context ===
-{{Quotation | Iestyn Bleasdale-Shepherd
-| Most players don't realize that the ping tool is context sensitive.  When they are playing voice enabled, players usually rely on the look portion of the ping tool.   Without voice, icons such as 'press the button' or 'stand here' become much more important.
 }}
@@ Line 225: / Line 210: @@
 {{Quotation | Brian Jacobson
 | It is important to give co-op players a way to coordinate their action.  Seeing how our players naturally wanted this ability, we decided to support it with the ping timer,  and ended up designing some puzzles around it.  Due to lag and other issues, syncing up actions over voice chat turned out to be rather difficult.  Therefore we created the countdown timer as a way for players to keep in sync.  It's completely predictable.  Both players see the GO at the same instant, and the clocks run in sync even if they are on different systems.
-}}
-=== Hand Off ===
-{{Quotation | Chris Boyd
-| Something that really surprised us was how often playtesters stated that they loved the basic experience of handing off a cube to their partner.  Players didn't expect such a fundamental physical interaction to just work in a game.  Before trying it for the first time, they would discuss their plan as if it were some unique or special new game mechanic.  When it just worked, they were overjoyed.
-}}
-=== Dying All The Time ===
-{{Quotation | Andrea Wicklund
-| Normally in games, when players die, they see this as a big failure.  But in Portal, death is a normal part of the puzzle solving experience.  In co-op, death not only happens more frequently, but it can happen at the hands of your partner (purely accidentally of course).  We felt it was important to not only make death "no big deal," but to make it fun.  Early on, we tried some elaborate death animations--such as showing your robot slowly getting crushed under a giant crusher.  These were awesome to watch, but they quickly became repetitive.  Also, after a very short while, players grew afraid to take risks.  The fear of having to wait a long time before trying again prevented them from simply playing and experimenting in a spirit of fun.  We had to find the right balance where death was quick enough to be a non-penalty, and elaborate enough to be visceral and satisfying--a fun pay-off for creative play.
 }}
@@ Line 240: / Line 215: @@
 {{Quotation | Danika Wright
 | Since the co-op characters can die at any time, we needed a way to rebuild them quickly and often.  Therefore in co-op, we replaced the elevators that connected test chambers in singleplayer, with disassembly machines.  These are meant to reinforce the idea that since the robots are disposable, being destroyed is no big deal.  In the robot world, it happens all the time!
-}}
-=== Airlocks ===
-{{Quotation | Garret Rickey
-| Airlocks were introduced mainly as a way to allow players to focus on individual puzzles.  In some of our early investigations, areas contained puzzles that were meant to be solved as a group, as well as others that were for individual solution.  But we found that if players could move freely between them, they logically assumed that the individual puzzles were part of one big puzzle.  This had bad results.  For clarity, we created these airlock-like spawn rooms that act as checkpoints between puzzles.  Once both players enter the airlock, we lock off access.
-}}
-=== World Imposters ===
-{{Quotation | Gary McTaggart
-| In Left 4 Dead 2, we authored simple, fogged, black versions of the world as monolithic models to avoid the CPU overhead of rendering the world again for water reflections. This worked well for the Left 4 Dead 2 outdoor environments where most light comes from the sky.  But Portal 2 is almost entirely indoors, so the color and value of the world geometry is apparent in the water reflections. Since the Portal 2 world geometry is relatively simple, we automatically build a version of the world geometry that has a single texture that combines both lighting and surface shading along with another texture with just surface shading. The latter texture is used when rendering dynamic lights.  These textures are at the same spatial resolution as the light maps and get packed into a single large atlased texture per level. Drawing this simple world imposter model takes very little CPU time, which was a limited resource on Portal 2 due to the many portal views, split-screen views, and water reflection views that we needed to render. We initially planned on using the world imposters only for water reflection rendering, but we ended up using it to improve performance in split-screen mode where it is used for rendering distant portals and portals that are two levels deep.  We also use the world imposters to render water in full screen co-op mode, to give us some performance overhead, since the co-op mode has more portal views to render than single-player mode.
 }}
@@ Line 255: / Line 220: @@
 {{Quotation | David Feise, Three Gels
 | With the gel sounds for Portal 2 we wanted to create something whimsical that would add to the player’s enjoyment of the mechanics, without crossing over the line into ludicrousness.  For example, our initial pass at the blue gel 'bounce' sound included a rubber playground ball, a pitch-bent harp string and a processed mouth harp.  The resulting sound captured the idea of fun, but was off the charts on the goofy scale.  After several iterations we settled on the current, less over-the-top sound which features a piece of metal bar bouncing like a diving board and a heavy dose of synthesis.  It’s not as wacky, but hopefully it’s still fun.
-}}
-=== Gesture Wheel ===
-{{Quotation | Andrew Burke
-| In our first implementation, gestures were automatically selected based on the player's context.  For example, Blue might do a special gesture when standing on a floor button. Players became bored of seeing these gestures so quickly that they stopped using them before discovering any of the special contexts.  Because of this, we decided to give players control of gestures as a way to express themselves, but when shown the full set from the start, they were overwhelmed by all the choices. By awarding gestures as the game progresses, we allow players to familiarize themselves with each gesture in turn.  Leaving visible empty slots in the gesture wheel lets players anticipate that they'll be rewarded with cool new gestures as they progress.  The gesture wheel provides quick access so that players can feel comfortable tossing out a gesture during down time, letting them pick the perfect moment to share a high five.
-}}
-=== High-Five ===
-{{Quotation | Matthew Scott
-| We noticed that after playtesters had solved a difficult puzzle together, they'd sometimes pause before funneling through the exit door to repeatedly jump up and down in excitement. We realized that these meeting points would be the perfect time to allow players to high-five each other and celebrate their victory in style. Our first interface attempt had one player initiate a high five by holding their hand up and waiting, the other player could join in by selecting the same gesture. If they were standing in the correct positions relative to each other, they would pull off a high five. But learning the correct places to stand was too difficult. So we decided to automatically move the bots into the correct positions for the high five. Sometimes, however, the player who wanted to high five would be left hanging as the other player ran ahead without accepting. Increasing the time that the initiator waited with his hand up gave the other player time to return and accept, but being frozen in place for more than a few seconds was too frustrating. So finally, we made players auto-accept the team gestures. Now, when the mood strikes either player, the game always ensures a successful celebration.
 }}
@@ Line 375: / Line 330: @@
 {{Quotation | Jeep Barnett
 | This puzzle requires one of Portal’s trickiest logical leaps. Early playtesters often took longer than their patience would allow, and were nearly ripping out their hair by the time they’d finally solved it. But almost everyone insisted that the payoff was by far their favorite moment in all of co-op. We significantly reduced the average solution time by adding a puzzle just before this where two cubes repeatedly collide, but this almost completely robbed the appeal from what was once a high moment. So, instead we decided to make a few subtle adjustments and leave players with the responsibility to make the final leap. First we added a puzzle four  chambers earlier, to teach players to fling by cutting their hard light bridge and falling into a surface directly below. We then subconsciously prime the thought of midair collision by having players repeatedly ricochet weighted spheres against a hard light bridge. Finally, we designed this room’s layout, lighting, and decals so that players would see the entire space as a symmetrical whole and visualize the bots' fling path. By planting shards of the idea in their heads, we allow players to own that exciting dual collision epiphany while keeping their sanity intact.
-}}
-=== Trust Puzzles ===
-{{Quotation | Eric Tams
-| Several puzzles in the game require the players to take on distinct, intertwined roles. We called these asymmetric chambers 'Trust Puzzles,' because one player is often placing their life in the hands of the other. When one player accidentally kills the other it almost always ends in laughter. So much laughter, that we sometimes had to question if it really was a legitimate accident. These puzzles also require players to stay in constant communication, which naturally leads to some great moments of cooperative bonding. While some teams found these stressful, for many partners, these puzzles were their favorite type. But everyone agreed that they added needed variety and a nice change of pace.  And by swapping roles, each player can get an entirely different experience within the exact same puzzle.
 }}
@@ Line 445: / Line 395: @@
 * SSH backdoor for updates and monitoring (possible to watch exactly what people were seeing as they dialed in)
 * Combined might of internets is terrifying
+}}
+==Co-op commentary==
+. Confidence Building; {{code|mp_coop_catapult_1}}
+=== Gesture Wheel ===
+{{Quotation | Andrew Burke
+| In our first implementation, gestures were automatically selected based on the player's context.  For example, Blue might do a special gesture when standing on a floor button. Players became bored of seeing these gestures so quickly that they stopped using them before discovering any of the special contexts.  Because of this, we decided to give players control of gestures as a way to express themselves, but when shown the full set from the start, they were overwhelmed by all the choices. By awarding gestures as the game progresses, we allow players to familiarize themselves with each gesture in turn.  Leaving visible empty slots in the gesture wheel lets players anticipate that they'll be rewarded with cool new gestures as they progress.  The gesture wheel provides quick access so that players can feel comfortable tossing out a gesture during down time, letting them pick the perfect moment to share a high five.
+}}
+=== Stealing The Core ===
+{{Quotation | Ted Backman
+| We have a taunt where one robot steals the other's core. When implemented, it was the only taunt that required one person to initiate. Because of this we were afraid that it would be used for griefing. We were in the process of rethinking our approach when early playtesters rated this as their favorite taunt.  It was also the most used team taunt because it only required one player to initiate, and was easier to use than the others.  We ended up changing all the other team taunts to emulate the way stealing the core works.
+}}
+=== Airlocks ===
+{{Quotation | Garret Rickey
+| Airlocks were introduced mainly as a way to allow players to focus on individual puzzles.  In some of our early investigations, areas contained puzzles that were meant to be solved as a group, as well as others that were for individual solution.  But we found that if players could move freely between them, they logically assumed that the individual puzzles were part of one big puzzle.  This had bad results.  For clarity, we created these airlock-like spawn rooms that act as checkpoints between puzzles.  Once both players enter the airlock, we lock off access.
+}}
+=== World Imposters ===
+{{Quotation | Gary McTaggart
+| In Left 4 Dead 2, we authored simple, fogged, black versions of the world as monolithic models to avoid the CPU overhead of rendering the world again for water reflections. This worked well for the Left 4 Dead 2 outdoor environments where most light comes from the sky.  But Portal 2 is almost entirely indoors, so the color and value of the world geometry is apparent in the water reflections. Since the Portal 2 world geometry is relatively simple, we automatically build a version of the world geometry that has a single texture that combines both lighting and surface shading along with another texture with just surface shading. The latter texture is used when rendering dynamic lights.  These textures are at the same spatial resolution as the light maps and get packed into a single large atlased texture per level. Drawing this simple world imposter model takes very little CPU time, which was a limited resource on Portal 2 due to the many portal views, split-screen views, and water reflection views that we needed to render. We initially planned on using the world imposters only for water reflection rendering, but we ended up using it to improve performance in split-screen mode where it is used for rendering distant portals and portals that are two levels deep.  We also use the world imposters to render water in full screen co-op mode, to give us some performance overhead, since the co-op mode has more portal views to render than single-player mode.
+}}
+=== Dying All The Time ===
+{{Quotation | Andrea Wicklund
+| Normally in games, when players die, they see this as a big failure.  But in Portal, death is a normal part of the puzzle solving experience.  In co-op, death not only happens more frequently, but it can happen at the hands of your partner (purely accidentally of course).  We felt it was important to not only make death "no big deal," but to make it fun.  Early on, we tried some elaborate death animations--such as showing your robot slowly getting crushed under a giant crusher.  These were awesome to watch, but they quickly became repetitive.  Also, after a very short while, players grew afraid to take risks.  The fear of having to wait a long time before trying again prevented them from simply playing and experimenting in a spirit of fun.  We had to find the right balance where death was quick enough to be a non-penalty, and elaborate enough to be visceral and satisfying--a fun pay-off for creative play.
+}}
+=== High-Five ===
+{{Quotation | Matthew Scott
+| We noticed that after playtesters had solved a difficult puzzle together, they'd sometimes pause before funneling through the exit door to repeatedly jump up and down in excitement. We realized that these meeting points would be the perfect time to allow players to high-five each other and celebrate their victory in style. Our first interface attempt had one player initiate a high five by holding their hand up and waiting, the other player could join in by selecting the same gesture. If they were standing in the correct positions relative to each other, they would pull off a high five. But learning the correct places to stand was too difficult. So we decided to automatically move the bots into the correct positions for the high five. Sometimes, however, the player who wanted to high five would be left hanging as the other player ran ahead without accepting. Increasing the time that the initiator waited with his hand up gave the other player time to return and accept, but being frozen in place for more than a few seconds was too frustrating. So finally, we made players auto-accept the team gestures. Now, when the mood strikes either player, the game always ensures a successful celebration.
+}}
+=== Hand Off ===
+{{Quotation | Chris Boyd
+| Something that really surprised us was how often playtesters stated that they loved the basic experience of handing off a cube to their partner.  Players didn't expect such a fundamental physical interaction to just work in a game.  Before trying it for the first time, they would discuss their plan as if it were some unique or special new game mechanic.  When it just worked, they were overjoyed.
+}}
+=== Ping Tool ===
+{{Quotation | Josh Weier
+| Early on we realized that trying to tell your partner where to go, where to look or where to place a portal was going to be really hard.  Even with voice chat, saying 'over there' doesn't give enough information to your partner within the 3D space.  Players kept wanting to get up and point directly at their partner's screen.  We developed the ping tool to address this problem.  Because the ping tool was so important, we decided to train players in its use before we did anything else.  We held back on the vast majority of player actions and let the players focus entirely on the ping tool.  This is why the co-op bots start separated in a tube, without even the ability to walk or shoot a portal.
+}}
+=== Trust Puzzles ===
+{{Quotation | Eric Tams
+| Several puzzles in the game require the players to take on distinct, intertwined roles. We called these asymmetric chambers 'Trust Puzzles,' because one player is often placing their life in the hands of the other. When one player accidentally kills the other it almost always ends in laughter. So much laughter, that we sometimes had to question if it really was a legitimate accident. These puzzles also require players to stay in constant communication, which naturally leads to some great moments of cooperative bonding. While some teams found these stressful, for many partners, these puzzles were their favorite type. But everyone agreed that they added needed variety and a nice change of pace.  And by swapping roles, each player can get an entirely different experience within the exact same puzzle.
+}}
+=== Ping Context ===
+{{Quotation | Iestyn Bleasdale-Shepherd
+| Most players don't realize that the ping tool is context sensitive.  When they are playing voice enabled, players usually rely on the look portion of the ping tool.   Without voice, icons such as 'press the button' or 'stand here' become much more important.
 }}