Add examples demonstrating how to follow the player with a camera #12658
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An addition or correction to our examples
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alice-i-cecile
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I'm definitely interested by this! I will need some camera logic in my game and I'm currently using Dolly. Would be great to explore alternatives with the Bevy API. We could also add some user documentation/guide maybe ? Can I be assigned on it? |
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Assigned! Feel free to open up a draft PR early and ask for help :) |
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Thanks, I'll do that :) |
github-merge-queue bot
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# Objective This PR addresses the 2D part of #12658. I plan to separate the examples and make one PR per camera example. ## Solution Added a new top-down example composed of: - [x] Player keyboard movements - [x] UI for keyboard instructions - [x] Colors and bloom effect to see the movement of the player - [x] Camera smooth movement towards the player (lerp) ## Testing ```bash cargo run --features="wayland,bevy/dynamic_linking" --example 2d_top_down_camera ``` https://github.com/bevyengine/bevy/assets/10638479/95db0587-e5e0-4f55-be11-97444b795793
mockersf
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Jun 10, 2024
# Objective This PR addresses the 2D part of #12658. I plan to separate the examples and make one PR per camera example. ## Solution Added a new top-down example composed of: - [x] Player keyboard movements - [x] UI for keyboard instructions - [x] Colors and bloom effect to see the movement of the player - [x] Camera smooth movement towards the player (lerp) ## Testing ```bash cargo run --features="wayland,bevy/dynamic_linking" --example 2d_top_down_camera ``` https://github.com/bevyengine/bevy/assets/10638479/95db0587-e5e0-4f55-be11-97444b795793
Hi @alice-i-cecile , regarding this example do we want to just control the camera or create some kind of character with some behaviours and attach the camera to it? |
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I'd like to have a simple character with basic movement. The camera shouldn't be controlled directly by the player, only the character. |
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# Objective A very common way to organize a first-person view is to split it into two kinds of models: - The *view model* is the model that represents the player's body. - The *world model* is everything else. The reason for this distinction is that these two models should be rendered with different FOVs. The view model is typically designed and animated with a very specific FOV in mind, so it is generally *fixed* and cannot be changed by a player. The world model, on the other hand, should be able to change its FOV to accommodate the player's preferences for the following reasons: - *Accessibility*: How prone is the player to motion sickness? A wider FOV can help. - *Tactical preference*: Does the player want to see more of the battlefield? Or have a more zoomed-in view for precision aiming? - *Physical considerations*: How well does the in-game FOV match the player's real-world FOV? Are they sitting in front of a monitor or playing on a TV in the living room? How big is the screen? ## Solution I've added an example implementing the described setup as follows. The `Player` is an entity holding two cameras, one for each model. The view model camera has a fixed FOV of 70 degrees, while the world model camera has a variable FOV that can be changed by the player. I use different `RenderLayers` to select what to render. - The world model camera has no explicit `RenderLayers` component, so it uses the layer 0. All static objects in the scene are also on layer 0 for the same reason. - The view model camera has a `RenderLayers` component with layer 1, so it only renders objects explicitly assigned to layer 1. The arm of the player is one such object. The order of the view model camera is additionally bumped to 1 to ensure it renders on top of the world model. - The light source in the scene must illuminate both the view model and the world model, so it is assigned to both layers 0 and 1. To better see the effect, the player can move the camera by dragging their mouse and change the world model's FOV with the arrow keys. The arrow up key maps to "decrease FOV" and the arrow down key maps to "increase FOV". This sounds backwards on paper, but is more intuitive when actually changing the FOV in-game since a decrease in FOV looks like a zoom-in. I intentionally do not allow changing the view model's FOV even though it would be illustrative because that would be an anti-pattern and bloat the code a bit. The example is called `first_person_view_model` and not just `first_person` because I want to highlight that this is not a simple flycam, but actually renders the player. ## Testing Default FOV: <img width="1392" alt="image" src="https://github.com/bevyengine/bevy/assets/9047632/8c2e804f-fac2-48c7-8a22-d85af999dfb2"> Decreased FOV: <img width="1392" alt="image" src="https://github.com/bevyengine/bevy/assets/9047632/1733b3e5-f583-4214-a454-3554e3cbd066"> Increased FOV: <img width="1392" alt="image" src="https://github.com/bevyengine/bevy/assets/9047632/0b0640e6-5743-46f6-a79a-7181ba9678e8"> Note that the white bar on the right represents the player's arm, which is more obvious in-game because you can move the camera around. The box on top is there to make sure that the view model is receiving shadows. I tested only on macOS. --- ## Changelog I don't think new examples go in here, do they? ## Caveat The solution used here was implemented with help by @robtfm on [Discord](https://discord.com/channels/691052431525675048/866787577687310356/1241019224491561000): > shadow maps are specific to lights, not to layers > if you want shadows from some meshes that are not visible, you could have light on layer 1+2, meshes on layer 2, camera on layer 1 (for example) > but this might change in future, it's not exactly an intended feature In other words, the example code as-is is not guaranteed to work in the future. I want to bring this up because the use-case presented here is extremely common in first-person games and important for accessibility. It would be good to have a blessed and easy way of how to achieve it. I'm also not happy about how I get the `perspective` variable in `change_fov`. Very open to suggestions :) ## Related issues - Addresses parts of #12658 - Addresses parts of #12588 --------- Co-authored-by: Pascal Hertleif <killercup@gmail.com>
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I think the previous example is enough to cover the needs of a first person camera - that's pretty much what I had in mind to attach the camera to the player. If it's ok we can close this issue as resolved. But if you need something else let me know 👍 |
mockersf
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Jun 19, 2024
# Objective A very common way to organize a first-person view is to split it into two kinds of models: - The *view model* is the model that represents the player's body. - The *world model* is everything else. The reason for this distinction is that these two models should be rendered with different FOVs. The view model is typically designed and animated with a very specific FOV in mind, so it is generally *fixed* and cannot be changed by a player. The world model, on the other hand, should be able to change its FOV to accommodate the player's preferences for the following reasons: - *Accessibility*: How prone is the player to motion sickness? A wider FOV can help. - *Tactical preference*: Does the player want to see more of the battlefield? Or have a more zoomed-in view for precision aiming? - *Physical considerations*: How well does the in-game FOV match the player's real-world FOV? Are they sitting in front of a monitor or playing on a TV in the living room? How big is the screen? ## Solution I've added an example implementing the described setup as follows. The `Player` is an entity holding two cameras, one for each model. The view model camera has a fixed FOV of 70 degrees, while the world model camera has a variable FOV that can be changed by the player. I use different `RenderLayers` to select what to render. - The world model camera has no explicit `RenderLayers` component, so it uses the layer 0. All static objects in the scene are also on layer 0 for the same reason. - The view model camera has a `RenderLayers` component with layer 1, so it only renders objects explicitly assigned to layer 1. The arm of the player is one such object. The order of the view model camera is additionally bumped to 1 to ensure it renders on top of the world model. - The light source in the scene must illuminate both the view model and the world model, so it is assigned to both layers 0 and 1. To better see the effect, the player can move the camera by dragging their mouse and change the world model's FOV with the arrow keys. The arrow up key maps to "decrease FOV" and the arrow down key maps to "increase FOV". This sounds backwards on paper, but is more intuitive when actually changing the FOV in-game since a decrease in FOV looks like a zoom-in. I intentionally do not allow changing the view model's FOV even though it would be illustrative because that would be an anti-pattern and bloat the code a bit. The example is called `first_person_view_model` and not just `first_person` because I want to highlight that this is not a simple flycam, but actually renders the player. ## Testing Default FOV: <img width="1392" alt="image" src="https://github.com/bevyengine/bevy/assets/9047632/8c2e804f-fac2-48c7-8a22-d85af999dfb2"> Decreased FOV: <img width="1392" alt="image" src="https://github.com/bevyengine/bevy/assets/9047632/1733b3e5-f583-4214-a454-3554e3cbd066"> Increased FOV: <img width="1392" alt="image" src="https://github.com/bevyengine/bevy/assets/9047632/0b0640e6-5743-46f6-a79a-7181ba9678e8"> Note that the white bar on the right represents the player's arm, which is more obvious in-game because you can move the camera around. The box on top is there to make sure that the view model is receiving shadows. I tested only on macOS. --- ## Changelog I don't think new examples go in here, do they? ## Caveat The solution used here was implemented with help by @robtfm on [Discord](https://discord.com/channels/691052431525675048/866787577687310356/1241019224491561000): > shadow maps are specific to lights, not to layers > if you want shadows from some meshes that are not visible, you could have light on layer 1+2, meshes on layer 2, camera on layer 1 (for example) > but this might change in future, it's not exactly an intended feature In other words, the example code as-is is not guaranteed to work in the future. I want to bring this up because the use-case presented here is extremely common in first-person games and important for accessibility. It would be good to have a blessed and easy way of how to achieve it. I'm also not happy about how I get the `perspective` variable in `change_fov`. Very open to suggestions :) ## Related issues - Addresses parts of #12658 - Addresses parts of #12588 --------- Co-authored-by: Pascal Hertleif <killercup@gmail.com>
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What problem does this solve or what need does it fill?
Following a player with the camera is an essential task for a large fraction of games. However, there are several pitfalls for new game devs:
What solution would you like?
Add two examples that :
What alternative(s) have you considered?
We could ship first-party camera controllers. This is not as good of a solution, as these tend to need to be heavily modified by the end user.
It's better to teach the developer how to fish, and possibly link to other resources on designing good camera controllers.
Additional context
Once this is done, we can consider adding other camera controller examples in follow-up PRs: e.g. RTS-style cameras, or a third person over the shoulder camera.
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