render: simple PCF

examples/shadows/src/main.rs

@@ -166,7 +166,7 @@ fn setup_scene_plugin(game: &mut Game) {
             light_tran,
         ));
 
-        world.spawn((
+        /* world.spawn((
             //cube_mesh.clone(),
             PointLight {
                 enabled: true,
@@ -188,7 +188,7 @@ fn setup_scene_plugin(game: &mut Game) {
                 ..Default::default()
             },
             Transform::from_xyz(-0.5, 2.0, -5.0),
-        ));
+        )); */
     }
 
     let mut camera = CameraComponent::new_3d();

lyra-game/src/render/graph/passes/meshes.rs

@@ -142,7 +142,7 @@ impl Node for MeshPass {
                     wgpu::BindGroupLayoutEntry {
                         binding: 1,
                         visibility: wgpu::ShaderStages::FRAGMENT,
-                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+                        ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Comparison),
                         count: None,
                     },
                     wgpu::BindGroupLayoutEntry {

lyra-game/src/render/graph/passes/shadows.rs

@@ -114,6 +114,7 @@ impl ShadowMapsPass {
             min_filter: wgpu::FilterMode::Linear,
             mipmap_filter: wgpu::FilterMode::Linear,
             border_color: Some(wgpu::SamplerBorderColor::OpaqueWhite),
+            compare: Some(wgpu::CompareFunction::LessEqual),
             ..Default::default()
         });
 

lyra-game/src/render/material.rs

@@ -58,7 +58,7 @@ impl Material {
             //diffuse: glam::Vec3::new(value.base_color.x, value.base_color.y, value.base_color.z),
             //diffuse: glam::Vec3::new(1.0, 0.5, 0.31),
             //specular: glam::Vec3::new(0.5, 0.5, 0.5),
-            ambient: glam::Vec3::new(1.0, 1.0, 1.0),
+            ambient: glam::Vec3::new(1.0, 1.0, 1.0) * 0.5,
             diffuse: glam::Vec3::new(1.0, 1.0, 1.0),
             shininess: 32.0,
 

lyra-game/src/render/shaders/base.wgsl

@@ -8,6 +8,8 @@ const LIGHT_TY_SPOT = 2u;
 
 const ALPHA_CUTOFF = 0.1;
 
+const SHADOW_MAP_PCF_SIZE = 4.0;
+
 struct VertexInput {
     @location(0) position: vec3<f32>,
     @location(1) tex_coords: vec2<f32>,
@@ -128,7 +130,7 @@ var t_light_grid: texture_storage_2d<rg32uint, read_write>; // rg32uint = vec2<u
 @group(5) @binding(0)
 var t_shadow_maps_atlas: texture_depth_2d;
 @group(5) @binding(1)
-var s_shadow_maps_atlas: sampler;
+var s_shadow_maps_atlas: sampler_comparison;
 @group(5) @binding(2)
 var<uniform> u_shadow_maps_atlas_size: vec2<u32>;
 @group(5) @binding(3)
@@ -165,7 +167,7 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
             let shadow_u: LightShadowMapUniform = u_light_shadow[light.light_shadow_uniform_index[0]];
             let frag_pos_light_space = shadow_u.light_space_matrix * vec4<f32>(in.world_position, 1.0);
 
-            let shadow = calc_shadow_dir_light(in.world_normal, light_dir, frag_pos_light_space, atlas_dimensions, shadow_u.atlas_frame);
+            let shadow = calc_shadow_dir_light(in.world_normal, light_dir, frag_pos_light_space, atlas_dimensions, shadow_u);
             light_res += blinn_phong_dir_light(in.world_position, in.world_normal, light, u_material, specular_color, shadow);
         } else if (light.light_ty == LIGHT_TY_POINT) {
             let shadow = calc_shadow_point(in.world_position, in.world_normal, light_dir, light, atlas_dimensions);
@@ -240,45 +242,60 @@ fn get_side_idx(tex_coord: vec3<f32>) -> vec3<f32> {
     return vec3<f32>(res, f32(cube_idx));
 }
 
-fn calc_shadow_dir_light(normal: vec3<f32>, light_dir: vec3<f32>, frag_pos_light_space: vec4<f32>, atlas_dimensions: vec2<i32>, atlas_region: TextureAtlasFrame) -> f32 {
+fn calc_shadow_dir_light(normal: vec3<f32>, light_dir: vec3<f32>, frag_pos_light_space: vec4<f32>, atlas_dimensions: vec2<i32>, shadow_u: LightShadowMapUniform) -> f32 {
     var proj_coords = frag_pos_light_space.xyz / frag_pos_light_space.w;
     // for some reason the y component is flipped after transforming
     proj_coords.y = -proj_coords.y;
 
-    // dont cast shadows outside the light's far plane
-    if (proj_coords.z > 1.0) {
-        return 0.0;
-    }
-
     // Remap xy to [0.0, 1.0]
     let xy_remapped = proj_coords.xy * 0.5 + 0.5;
 
-    // no need to get the y since the maps are square
+    // get the atlas frame in [0; 1] in the atlas texture
-    let atlas_start = f32(atlas_region.x) / f32(atlas_dimensions.x);
+    // z is width, w is height
-    let atlas_end = f32(atlas_region.x + atlas_region.width) / f32(atlas_dimensions.x);
+    var region_rect = vec4<f32>(f32(shadow_u.atlas_frame.x), f32(shadow_u.atlas_frame.y), f32(shadow_u.atlas_frame.width), f32(shadow_u.atlas_frame.height));
-    // lerp the tex coords to the shadow map for this light.
+    region_rect /= f32(atlas_dimensions.x);
-    proj_coords.x = mix(atlas_start, atlas_end, xy_remapped.x);
+    let region_coords = vec2<f32>(
-    proj_coords.y = mix(atlas_start, atlas_end, xy_remapped.y);
+        mix(region_rect.x, region_rect.x + region_rect.z, xy_remapped.x),
-
+        mix(region_rect.y, region_rect.y + region_rect.w, xy_remapped.y)
-    // simulate `ClampToBorder`, not creating shadows past the shadow map regions
+    );
-    if (proj_coords.x > atlas_end && proj_coords.y > atlas_end)
-            || (proj_coords.x < atlas_start && proj_coords.y < atlas_start) {
-        return 0.0;
-    }
-
-    // must manually apply offset to the texture coords since `textureSampleLevel` requires a
-    // const value.
-    let offset_coords = proj_coords.xy + (vec2<f32>(f32(atlas_region.x), f32(atlas_region.y)) / vec2<f32>(atlas_dimensions));
-    let closest_depth = textureSampleLevel(t_shadow_maps_atlas, s_shadow_maps_atlas, offset_coords, 0.0);
-    let current_depth = proj_coords.z;
     
     // use a bias to avoid shadow acne
     let bias = max(0.05 * (1.0 - dot(normal, light_dir)), 0.005);  
-    var shadow = 0.0;
+    let current_depth = proj_coords.z - bias;
-    if current_depth - bias > closest_depth {
+
+    var shadow = pcf_dir_light(region_coords, current_depth, shadow_u);
+
+    // dont cast shadows outside the light's far plane
+    if (proj_coords.z > 1.0) {
         shadow = 1.0;
     }
 
+    // dont cast shadows if the texture coords would go past the shadow maps
+    if (xy_remapped.x > 1.0 || xy_remapped.x < 0.0 || xy_remapped.y > 1.0 || xy_remapped.y < 0.0) {
+        shadow = 1.0;
+    }
+
+    return shadow;
+}
+
+/// Calculate the shadow coefficient using PCF of a directional light
+fn pcf_dir_light(tex_coords: vec2<f32>, test_depth: f32, shadow_u: LightShadowMapUniform) -> f32 {
+    let half_filter_size = SHADOW_MAP_PCF_SIZE / 2.0;
+    let texel_size = 1.0 / vec2<f32>(f32(shadow_u.atlas_frame.width), f32(shadow_u.atlas_frame.height));
+
+    // Sample PCF 
+    var shadow = 0.0;
+    for (var x = -half_filter_size; x <= half_filter_size; x += 1.0) {
+        for (var y = -half_filter_size; y <= half_filter_size; y += 1.0) {
+            let offset = tex_coords + vec2<f32>(x, y) * texel_size;
+            let pcf_depth = textureSampleCompare(t_shadow_maps_atlas, s_shadow_maps_atlas, offset, test_depth);
+            shadow += pcf_depth;
+        }
+    }
+    shadow /= pow(SHADOW_MAP_PCF_SIZE, 2.0);
+    // ensure the shadow value does not go above 1.0
+    shadow = min(shadow, 1.0);
+
     return shadow;
 }
 
@@ -289,9 +306,9 @@ fn calc_shadow_point(world_pos: vec3<f32>, world_normal: vec3<f32>, light_dir: v
     let cube_idx = i32(temp.z);
     
     /// if an unknown cube side was returned, something is broken
-    if cube_idx == 0 {
+    /*if cube_idx == 0 {
         return 0.0;
-    }
+    }*/
 
     var indices = light.light_shadow_uniform_index;
     let i = indices[cube_idx - 1];
@@ -303,27 +320,20 @@ fn calc_shadow_point(world_pos: vec3<f32>, world_normal: vec3<f32>, light_dir: v
     region_coords /= f32(atlas_dimensions.x);
 
     // simulate `ClampToBorder`, not creating shadows past the shadow map regions
-    if (coords_2d.x >= 1.0 || coords_2d.y >= 1.0) {
+    /*if (coords_2d.x >= 1.0 || coords_2d.y >= 1.0) {
         return 0.0;
-    }
+    }*/
 
     // get the coords inside of the region
     coords_2d.x = mix(region_coords.x, region_coords.x + region_coords.z, coords_2d.x);
     coords_2d.y = mix(region_coords.y, region_coords.y + region_coords.w, coords_2d.y);
 
-    var closest_depth = textureSampleLevel(t_shadow_maps_atlas, s_shadow_maps_atlas, coords_2d, 0.0);
-    let current_depth = length(frag_to_light);
-    
-    // convert depth from [0; 1] to the original depth value
-    closest_depth *= u.far_plane;
-
     // use a bias to avoid shadow acne
     let bias = max(0.05 * (1.0 - dot(world_normal, light_dir)), 0.005);
+    var current_depth = length(frag_to_light) - bias;
+    current_depth /= u.far_plane;
 
-    var shadow = 0.0;
+    var shadow = textureSampleCompare(t_shadow_maps_atlas, s_shadow_maps_atlas, coords_2d, current_depth);
-    if current_depth - bias > closest_depth {
-        shadow = 1.0;
-    }
 
     return shadow;
 }
@@ -369,7 +379,7 @@ fn blinn_phong_dir_light(world_pos: vec3<f32>, world_norm: vec3<f32>, dir_light:
     diffuse_color *= dir_light.diffuse;
     specular_color *= dir_light.specular;*/
 
-    return (ambient_color + (1.0 - shadow) * (diffuse_color + specular_color)) * dir_light.intensity;
+    return (ambient_color + (shadow) * (diffuse_color + specular_color)) * dir_light.intensity;
 }
 
 fn blinn_phong_point_light(world_pos: vec3<f32>, world_norm: vec3<f32>, point_light: Light, material: Material, specular_factor: vec3<f32>, shadow: f32) -> vec3<f32> {