Strange light behavior with different far plane values of orthographic camera

[kirusfg]

Bevy version

latest (8630b19)

Operating system & version

OS: Artix Linux x86_64
Linux Kernel: 5.17.2-zen2-1-zen
GPU: NVIDIA GeForce 920MX
Nvidia driver: 510.60.02-1

What you did

Loaded a glTF scene with an orthographic camera and a point light in it:

use bevy::prelude::*;


fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
    commands.spawn_scene(asset_server.load("ortho10.gltf#Scene0"));
}


fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_startup_system(setup)
        .run();
}

To test and experiment with this, edit the zfar field of the camera in the file provided:

ortho10.gtlf

{
    "asset" : {
        "generator" : "Khronos glTF Blender I/O v1.8.19",
        "version" : "2.0"
    },
    "extensionsUsed" : [
        "KHR_lights_punctual"
    ],
    "extensionsRequired" : [
        "KHR_lights_punctual"
    ],
    "extensions" : {
        "KHR_lights_punctual" : {
            "lights" : [
                {
                    "color" : [
                        1,
                        1,
                        1
                    ],
                    "intensity" : 1000,
                    "type" : "point",
                    "name" : "Light.001"
                }
            ]
        }
    },
    "scene" : 0,
    "scenes" : [
        {
            "name" : "Scene",
            "nodes" : [
                0,
                3,
                6,
                7
            ]
        }
    ],
    "nodes" : [
        {
            "mesh" : 0,
            "name" : "Cube",
            "translation" : [
                0,
                1,
                0
            ]
        },
        {
            "extensions" : {
                "KHR_lights_punctual" : {
                    "light" : 0
                }
            },
            "name" : "Light_Orientation_Orientation",
            "rotation" : [
                -0.7071067690849304,
                0,
                0,
                0.7071067690849304
            ]
        },
        {
            "children" : [
                1
            ],
            "name" : "Light_Orientation"
        },
        {
            "children" : [
                2
            ],
            "name" : "Light",
            "rotation" : [
                0.16907575726509094,
                0.7558803558349609,
                -0.27217137813568115,
                0.570947527885437
            ],
            "translation" : [
                4.076245307922363,
                5.903861999511719,
                -1.0054539442062378
            ]
        },
        {
            "camera" : 0,
            "name" : "Camera_Orientation_Orientation",
            "rotation" : [
                -0.7071067690849304,
                0,
                0,
                0.7071067690849304
            ]
        },
        {
            "children" : [
                4
            ],
            "name" : "Camera_Orientation"
        },
        {
            "children" : [
                5
            ],
            "name" : "Camera",
            "rotation" : [
                0.40501639246940613,
                0.4532789885997772,
                -0.24283890426158905,
                0.7559954524040222
            ],
            "translation" : [
                7.977607727050781,
                6.902405738830566,
                4.161380290985107
            ]
        },
        {
            "mesh" : 1,
            "name" : "Plane",
            "scale" : [
                10.624591827392578,
                10.624591827392578,
                10.624591827392578
            ]
        }
    ],
    "cameras" : [
        {
            "name" : "Camera.001",
            "orthographic" : {
                "xmag" : 10,
                "ymag" : 10,
                "zfar" : 100,
                "znear" : 0.10000000149011612
            },
            "type" : "orthographic"
        }
    ],
    "materials" : [
        {
            "doubleSided" : true,
            "name" : "Material.001",
            "pbrMetallicRoughness" : {
                "baseColorFactor" : [
                    0.057456985116004944,
                    0.0665164664387703,
                    0.8000000715255737,
                    1
                ],
                "metallicFactor" : 0,
                "roughnessFactor" : 0.4000000059604645
            }
        },
        {
            "doubleSided" : true,
            "name" : "Material.002",
            "pbrMetallicRoughness" : {
                "baseColorFactor" : [
                    0.8000000715255737,
                    0.2788206934928894,
                    0.2428315132856369,
                    1
                ],
                "metallicFactor" : 0,
                "roughnessFactor" : 0.5
            }
        }
    ],
    "meshes" : [
        {
            "name" : "Cube.001",
            "primitives" : [
                {
                    "attributes" : {
                        "POSITION" : 0,
                        "NORMAL" : 1,
                        "TEXCOORD_0" : 2
                    },
                    "indices" : 3,
                    "material" : 0
                }
            ]
        },
        {
            "name" : "Plane",
            "primitives" : [
                {
                    "attributes" : {
                        "POSITION" : 4,
                        "NORMAL" : 5,
                        "TEXCOORD_0" : 6
                    },
                    "indices" : 7,
                    "material" : 1
                }
            ]
        }
    ],
    "accessors" : [
        {
            "bufferView" : 0,
            "componentType" : 5126,
            "count" : 24,
            "max" : [
                1,
                1,
                1
            ],
            "min" : [
                -1,
                -1,
                -1
            ],
            "type" : "VEC3"
        },
        {
            "bufferView" : 1,
            "componentType" : 5126,
            "count" : 24,
            "type" : "VEC3"
        },
        {
            "bufferView" : 2,
            "componentType" : 5126,
            "count" : 24,
            "type" : "VEC2"
        },
        {
            "bufferView" : 3,
            "componentType" : 5123,
            "count" : 36,
            "type" : "SCALAR"
        },
        {
            "bufferView" : 4,
            "componentType" : 5126,
            "count" : 4,
            "max" : [
                1,
                0,
                1
            ],
            "min" : [
                -1,
                0,
                -1
            ],
            "type" : "VEC3"
        },
        {
            "bufferView" : 5,
            "componentType" : 5126,
            "count" : 4,
            "type" : "VEC3"
        },
        {
            "bufferView" : 6,
            "componentType" : 5126,
            "count" : 4,
            "type" : "VEC2"
        },
        {
            "bufferView" : 7,
            "componentType" : 5123,
            "count" : 6,
            "type" : "SCALAR"
        }
    ],
    "bufferViews" : [
        {
            "buffer" : 0,
            "byteLength" : 288,
            "byteOffset" : 0
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        {
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            "buffer" : 0,
            "byteLength" : 192,
            "byteOffset" : 576
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            "byteOffset" : 768
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            "byteOffset" : 840
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            "buffer" : 0,
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            "byteOffset" : 888
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            "byteLength" : 32,
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}

What you expected to happen

Proper lighting

What actually happened

Lighting behaving strangely on different far settings of the orthographic camera set in Blender:

30

50

100

1000

Additional Information

Note that at a 1000, the lighted parts of the scene are not visible in a 16:9 window and I had to stretch it. In #4005, the light was being "cutoff" because the far value was not loaded from glTF, and by default, it was being set to 0. Same thing is happening here.

[robtfm]

I think this will be fixed by #4345 - specifically the small pbr.wgsl change from that pr. could you please check?
If that works and if the whole pr is too big for 0.7 perhaps we can separate out the pbr.wgsl change into a separate pr and merge it more quickly.

[kirusfg]

Yes, the issue is fixed there, great work!

Do not forget to mark this issue as being resolved by #4345.

[superdump]

To flesh out the test results a bit with what @kirusfg found and reported on Discord:

• The pbr.wgsl change from [Merged by Bors] - Faster assign lights to clusters #4345 applied on top of main was not enough to fix the problem
• Nor was additionally applying the extra match case for first_slice_depth in src/light.rs from [Merged by Bors] - Faster assign lights to clusters #4345
• [Merged by Bors] - Faster assign lights to clusters #4345 as a whole does fix the problem

[superdump]

One more note, the following has been tested as an effective workaround:

ClusterConfig::FixedZ {
    total: 4096,
    z_slices: 24,
    z_config: ClusterZConfig {
        first_slice_depth: 5.0,
        far_z_mode: ClusterFarZMode::CameraFarPlane,
    },
    dynamic_resizing: false,
}

Basically ensuring that the far z plane used for clustering matches the far z plane of the camera.

[kirusfg]

Fixed by #4345.