Improve the entity depth calculation and shadow rendering

korangar/src/graphics/instruction.rs

@@ -77,6 +77,7 @@ pub struct WaterInstruction<'a> {
 #[derive(Clone, Debug)]
 pub struct DirectionalShadowCasterInstruction {
     pub view_projection_matrix: Matrix4<f32>,
+    pub view_matrix: Matrix4<f32>,
     pub direction: Vector3<f32>,
     pub color: Color,
 }
@@ -86,6 +87,7 @@ pub struct DirectionalShadowCasterInstruction {
 #[derive(Clone, Debug)]
 pub struct PointShadowCasterInstruction {
     pub view_projection_matrices: [Matrix4<f32>; 6],
+    pub view_matrices: [Matrix4<f32>; 6],
     pub position: Point3<f32>,
     pub color: Color,
     pub range: f32,

korangar/src/graphics/passes/directional_shadow/mod.rs

@@ -6,6 +6,7 @@ use std::num::NonZeroU64;
 use std::sync::OnceLock;
 
 use bytemuck::{Pod, Zeroable};
+use cgmath::{Matrix4, SquareMatrix};
 pub(crate) use entity::DirectionalShadowEntityDrawer;
 pub(crate) use indicator::DirectionalShadowIndicatorDrawer;
 pub(crate) use model::DirectionalShadowModelDrawer;
@@ -26,6 +27,8 @@ const PASS_NAME: &str = "directional shadow render pass";
 #[repr(C)]
 struct PassUniforms {
     view_projection: [[f32; 4]; 4],
+    view: [[f32; 4]; 4],
+    inverse_view: [[f32; 4]; 4],
     animation_timer: f32,
     padding: [u32; 3],
 }
@@ -132,6 +135,13 @@ impl Prepare for DirectionalShadowRenderPassContext {
     fn prepare(&mut self, _device: &Device, instructions: &RenderInstruction) {
         self.uniforms_data = PassUniforms {
             view_projection: instructions.directional_light_with_shadow.view_projection_matrix.into(),
+            view: instructions.directional_light_with_shadow.view_matrix.into(),
+            inverse_view: instructions
+                .directional_light_with_shadow
+                .view_matrix
+                .invert()
+                .unwrap_or(Matrix4::identity())
+                .into(),
             animation_timer: instructions.uniforms.animation_timer,
             padding: Default::default(),
         };

korangar/src/graphics/passes/directional_shadow/shader/entity.wgsl

@@ -1,5 +1,7 @@
 struct PassUniforms {
     view_projection: mat4x4<f32>,
+    view: mat4x4<f32>,
+    inverse_view: mat4x4<f32>,
     animation_timer: f32,
 }
 
@@ -20,18 +22,17 @@ struct InstanceData {
 struct Vertex {
     position: vec3<f32>,
     texture_coordinates: vec2<f32>,
-    depth_multiplier: f32,
-    curvature_multiplier: f32,
 }
 
 struct VertexOutput {
     @builtin(position) position: vec4<f32>,
-    @location(0) texture_coordinates: vec2<f32>,
-    @location(1) depth_offset: f32,
-    @location(2) curvature: f32,
-    @location(3) @interpolate(flat) original_depth_offset: f32,
-    @location(4) @interpolate(flat) original_curvature: f32,
-    @location(5) alpha: f32,
+    @location(0) world_position: vec4<f32>,
+    @location(1) texture_coordinates: vec2<f32>,
+    @location(2) depth_offset: f32,
+    @location(3) curvature: f32,
+    @location(4) @interpolate(flat) original_depth_offset: f32,
+    @location(5) @interpolate(flat) original_curvature: f32,
+    @location(6) alpha: f32,
 }
 
 @group(0) @binding(3) var texture_sampler: sampler;
@@ -47,9 +48,11 @@ fn vs_main(
     let instance = instance_data[instance_index];
     let vertex = vertex_data(vertex_index);
     let frame_part_vertex = instance.frame_part_transform * vec4<f32>(vertex.position, 1.0);
+    let world_position = instance.world * frame_part_vertex;
 
     var output: VertexOutput;
-    output.position = pass_uniforms.view_projection * instance.world * frame_part_vertex;
+    output.world_position = world_position;
+    output.position = pass_uniforms.view_projection * world_position;
     output.texture_coordinates = instance.texture_position + vertex.texture_coordinates * instance.texture_size;
 
     if (instance.mirror != 0u) {
@@ -67,7 +70,7 @@ fn vs_main(
     // Because we have to transform the vertex of the frame part, we can't use the depth and curvature
     // directly and are using the fact, that y / depth and x / curvature correlate to each other.
     // An offset is also added for frame parts not stay at the same depth.
-    output.depth_offset = (frame_part_vertex.y - 1.0) * proportion_y + instance.extra_depth_offset;
+    output.depth_offset = frame_part_vertex.y * proportion_y + instance.extra_depth_offset;
     output.curvature = frame_part_vertex.x * proportion_x;
 
     output.original_depth_offset = instance.depth_offset;
@@ -83,35 +86,30 @@ fn fs_main(input: VertexOutput) -> @builtin(frag_depth) f32 {
         discard;
     }
 
-    // TODO: This is only a temporary change, we will fix the depth_offset later.
-    // The idea for the temporary change is to create two parabolas to correct the plane inclination.
-    let sign_depth_offset = select(2.0, -2.0, input.depth_offset < 0.0);
-    let scaled_depth_offset = sign_depth_offset * pow(input.depth_offset, 2.0) * input.original_depth_offset;
-    let scaled_curvature_offset = (0.5 - pow(input.curvature, 2.0)) * input.original_curvature;
+    // Adjust the sprite as if it was standing upright
+    let depth_offset = input.depth_offset * input.original_depth_offset;
+    let curvature_offset = (0.5 - pow(input.curvature, 2.0)) * input.original_curvature;
+    let view_position = pass_uniforms.view * input.world_position;
+    let adjusted_view_position = view_position - vec4<f32>(0.0, 0.0, depth_offset + curvature_offset, 0.0);
+    let adjusted_world_position = pass_uniforms.inverse_view * adjusted_view_position;
+    let clip_position = pass_uniforms.view_projection * adjusted_world_position;
+    let depth = saturate(clip_position.z / clip_position.w);
 
-    // Shadows use orthographic projections, so values are linear, but "compressed".
-    let absolute_depth = decompress_depth_ortho(input.position.z);
-    let adjusted_linear_z: f32 = 3.5 + absolute_depth - scaled_depth_offset - scaled_curvature_offset;
-    let depth = compress_depth_ortho(adjusted_linear_z);
-    let clamped_depth = clamp(depth, 0.0, 1.0);
-
-    return clamped_depth;
+    return depth;
 }
 
 // Optimized version of the following truth table:
 //
-// vertex_index  x  y  z  u  v   d   c
-// 0            -1  2  1  0  0   1  -1
-// 1            -1  0  1  0  1  -1  -1
-// 2             1  2  1  1  0   1   1
-// 3             1  2  1  1  0   1   1
-// 4            -1  0  1  0  1  -1  -1
-// 5             1  0  1  1  1  -1   1
+// vertex_index  x  y  z  u  v
+// 0            -1  2  1  0  0
+// 1            -1  0  1  0  1
+// 2             1  2  1  1  0
+// 3             1  2  1  1  0
+// 4            -1  0  1  0  1
+// 5             1  0  1  1  1
 //
 // (x,y,z) are the vertex position
 // (u,v) are the UV coordinates
-// (depth) is the depth multiplier
-// (curve) is the curvature multiplier
 fn vertex_data(vertex_index: u32) -> Vertex {
     let index = 1u << vertex_index;
 
@@ -123,22 +121,6 @@ fn vertex_data(vertex_index: u32) -> Vertex {
     let z = 1.0;
     let u = f32(1 - case0);
     let v = f32(1 - case1);
-    let depth = y - 1.0;
-    let curve = x;
-
-    return Vertex(vec3<f32>(x, y, z), vec2<f32>(u, v), depth, curve);
-}
-
-fn decompress_depth_ortho(depth: f32) -> f32 {
-    let depth_scale = -pass_uniforms.view_projection[2][2];
-    let depth_far = pass_uniforms.view_projection[3][2];
-    let far = depth_far / depth_scale;
-    return far - depth / depth_scale;
-}
 
-fn compress_depth_ortho(depth: f32) -> f32 {
-    let depth_scale = -pass_uniforms.view_projection[2][2];
-    let depth_far = pass_uniforms.view_projection[3][2];
-    let far = depth_far / depth_scale;
-    return -depth * depth_scale + depth_far;
+    return Vertex(vec3<f32>(x, y, z), vec2<f32>(u, v));
 }

korangar/src/graphics/passes/directional_shadow/shader/entity_bindless.wgsl

@@ -1,5 +1,7 @@
 struct PassUniforms {
     view_projection: mat4x4<f32>,
+    view: mat4x4<f32>,
+    inverse_view: mat4x4<f32>,
     animation_timer: f32,
 }
 
@@ -20,19 +22,18 @@ struct InstanceData {
 struct Vertex {
     position: vec3<f32>,
     texture_coordinates: vec2<f32>,
-    depth_multiplier: f32,
-    curvature_multiplier: f32,
 }
 
 struct VertexOutput {
     @builtin(position) position: vec4<f32>,
-    @location(0) texture_coordinates: vec2<f32>,
-    @location(1) depth_offset: f32,
-    @location(2) curvature: f32,
-    @location(3) @interpolate(flat) original_depth_offset: f32,
-    @location(4) @interpolate(flat) original_curvature: f32,
-    @location(5) texture_index: i32,
-    @location(6) alpha: f32,
+    @location(0) world_position: vec4<f32>,
+    @location(1) texture_coordinates: vec2<f32>,
+    @location(2) depth_offset: f32,
+    @location(3) curvature: f32,
+    @location(4) @interpolate(flat) original_depth_offset: f32,
+    @location(5) @interpolate(flat) original_curvature: f32,
+    @location(6) texture_index: i32,
+    @location(7) alpha: f32,
 }
 
 @group(0) @binding(3) var texture_sampler: sampler;
@@ -48,9 +49,11 @@ fn vs_main(
     let instance = instance_data[instance_index];
     let vertex = vertex_data(vertex_index);
     let frame_part_vertex = instance.frame_part_transform * vec4<f32>(vertex.position, 1.0);
+    let world_position = instance.world * frame_part_vertex;
 
     var output: VertexOutput;
-    output.position = pass_uniforms.view_projection * instance.world * frame_part_vertex;
+    output.world_position = world_position;
+    output.position = pass_uniforms.view_projection * world_position;
     output.texture_coordinates = instance.texture_position + vertex.texture_coordinates * instance.texture_size;
 
     if (instance.mirror != 0u) {
@@ -68,7 +71,7 @@ fn vs_main(
     // Because we have to transform the vertex of the frame part, we can't use the depth and curvature
     // directly and are using the fact, that y / depth and x / curvature correlate to each other.
     // An offset is also added for frame parts not stay at the same depth.
-    output.depth_offset = (frame_part_vertex.y - 1.0) * proportion_y + instance.extra_depth_offset;
+    output.depth_offset = frame_part_vertex.y * proportion_y + instance.extra_depth_offset;
     output.curvature = frame_part_vertex.x * proportion_x;
 
     output.original_depth_offset = instance.depth_offset;
@@ -85,35 +88,30 @@ fn fs_main(input: VertexOutput) -> @builtin(frag_depth) f32 {
         discard;
     }
 
-    // TODO: This is only a temporary change, we will fix the depth_offset later.
-    // The idea for the temporary change is to create two parabolas to correct the plane inclination.
-    let sign_depth_offset = select(2.0, -2.0, input.depth_offset < 0.0);
-    let scaled_depth_offset = sign_depth_offset * pow(input.depth_offset, 2.0) * input.original_depth_offset;
-    let scaled_curvature_offset = (0.5 - pow(input.curvature, 2.0)) * input.original_curvature;
+    // Adjust the sprite as if it was standing upright
+    let depth_offset = input.depth_offset * input.original_depth_offset;
+    let curvature_offset = (0.5 - pow(input.curvature, 2.0)) * input.original_curvature;
+    let view_position = pass_uniforms.view * input.world_position;
+    let adjusted_view_position = view_position - vec4<f32>(0.0, 0.0, depth_offset + curvature_offset, 0.0);
+    let adjusted_world_position = pass_uniforms.inverse_view * adjusted_view_position;
+    let clip_position = pass_uniforms.view_projection * adjusted_world_position;
+    let depth = saturate(clip_position.z / clip_position.w);
 
-    // Shadows use orthographic projections, so values are linear, but "compressed".
-    let absolute_depth = decompress_depth_ortho(input.position.z);
-    let adjusted_linear_z: f32 = 3.5 + absolute_depth - scaled_depth_offset - scaled_curvature_offset;
-    let depth = compress_depth_ortho(adjusted_linear_z);
-    let clamped_depth = clamp(depth, 0.0, 1.0);
-
-    return clamped_depth;
+    return depth;
 }
 
 // Optimized version of the following truth table:
 //
-// vertex_index  x  y  z  u  v   d   c
-// 0            -1  2  1  0  0   1  -1
-// 1            -1  0  1  0  1  -1  -1
-// 2             1  2  1  1  0   1   1
-// 3             1  2  1  1  0   1   1
-// 4            -1  0  1  0  1  -1  -1
-// 5             1  0  1  1  1  -1   1
+// vertex_index  x  y  z  u  v
+// 0            -1  2  1  0  0
+// 1            -1  0  1  0  1
+// 2             1  2  1  1  0
+// 3             1  2  1  1  0
+// 4            -1  0  1  0  1
+// 5             1  0  1  1  1
 //
 // (x,y,z) are the vertex position
 // (u,v) are the UV coordinates
-// (depth) is the depth multiplier
-// (curve) is the curvature multiplier
 fn vertex_data(vertex_index: u32) -> Vertex {
     let index = 1u << vertex_index;
 
@@ -125,22 +123,6 @@ fn vertex_data(vertex_index: u32) -> Vertex {
     let z = 1.0;
     let u = f32(1 - case0);
     let v = f32(1 - case1);
-    let depth = y - 1.0;
-    let curve = x;
-
-    return Vertex(vec3<f32>(x, y, z), vec2<f32>(u, v), depth, curve);
-}
-
-fn decompress_depth_ortho(depth: f32) -> f32 {
-    let depth_scale = -pass_uniforms.view_projection[2][2];
-    let depth_far = pass_uniforms.view_projection[3][2];
-    let far = depth_far / depth_scale;
-    return far - depth / depth_scale;
-}
 
-fn compress_depth_ortho(depth: f32) -> f32 {
-    let depth_scale = -pass_uniforms.view_projection[2][2];
-    let depth_far = pass_uniforms.view_projection[3][2];
-    let far = depth_far / depth_scale;
-    return -depth * depth_scale + depth_far;
+    return Vertex(vec3<f32>(x, y, z), vec2<f32>(u, v));
 }

korangar/src/graphics/passes/directional_shadow/shader/indicator.wgsl

@@ -20,6 +20,8 @@ struct GlobalUniforms {
 
 struct PassUniforms {
     view_projection: mat4x4<f32>,
+    view: mat4x4<f32>,
+    inverse_view: mat4x4<f32>,
     animation_timer: f32,
 }
 

korangar/src/graphics/passes/directional_shadow/shader/model.wgsl

@@ -1,5 +1,7 @@
 struct PassUniforms {
     view_projection: mat4x4<f32>,
+    view: mat4x4<f32>,
+    inverse_view: mat4x4<f32>,
     animation_timer: f32,
 }