Add a perfect masking stencil

src/render/shader_ffi.rs

@@ -65,6 +65,27 @@ impl GpuVertexUniform {
     }
 }
 
+#[repr(C)]
+#[derive(Copy, Clone, Pod, Zeroable)]
+pub struct MaskInstanceUniform {
+    pub position: Vec2f32,
+    pub target_width: f32,
+    pub target_height: f32,
+    pub debug_color: Vec4f32,
+}
+
+impl MaskInstanceUniform {
+    pub fn new(position: Vec2f32, target_width: f32, target_height: f32, debug_color: Vec4f32) -> Self {
+        Self {
+            position,
+            target_width,
+            target_height,
+            debug_color
+        }
+    }
+}
+
+
 #[repr(C)]
 #[derive(Copy, Clone, Pod, Zeroable)]
 pub struct PrimitiveUniform {

src/render/shaders/mod.rs

@@ -105,9 +105,10 @@ pub mod tile {
 }
 
 pub mod tile_mask {
-    use super::{FragmentShaderState, VertexShaderState};
     use crate::platform::COLOR_TEXTURE_FORMAT;
-    use crate::render::shader_ffi::GpuVertexUniform;
+    use crate::render::shader_ffi::{GpuVertexUniform, MaskInstanceUniform};
+
+    use super::{FragmentShaderState, VertexShaderState};
 
     pub const VERTEX: VertexShaderState = VertexShaderState::new(
         include_str!("tile_mask.vertex.wgsl"),
@@ -116,16 +117,19 @@ pub mod tile_mask {
                 array_stride: std::mem::size_of::<GpuVertexUniform>() as u64,
                 step_mode: wgpu::VertexStepMode::Vertex,
                 attributes: &[
+                    // position
                     wgpu::VertexAttribute {
                         offset: 0,
                         format: wgpu::VertexFormat::Float32x2,
                         shader_location: 0,
                     },
+                    // normal
                     wgpu::VertexAttribute {
                         offset: wgpu::VertexFormat::Float32x2.size(),
                         format: wgpu::VertexFormat::Float32x2,
                         shader_location: 1,
                     },
+                    // ?
                     wgpu::VertexAttribute {
                         offset: 2 * wgpu::VertexFormat::Float32x2.size(),
                         format: wgpu::VertexFormat::Uint32,
@@ -134,13 +138,36 @@ pub mod tile_mask {
                 ],
             },
             wgpu::VertexBufferLayout {
-                array_stride: std::mem::size_of::<GpuVertexUniform>() as u64,
+                array_stride: std::mem::size_of::<MaskInstanceUniform>() as u64,
                 step_mode: wgpu::VertexStepMode::Instance,
-                attributes: &[wgpu::VertexAttribute {
+                attributes: &[
-                    offset: 0,
+                    // offset position
-                    format: wgpu::VertexFormat::Float32x2,
+                    wgpu::VertexAttribute {
-                    shader_location: 4,
+                        offset: 0,
-                }],
+                        format: wgpu::VertexFormat::Float32x2,
+                        shader_location: 4,
+                    },
+                    // target_width
+                    wgpu::VertexAttribute {
+                        offset: 1 * wgpu::VertexFormat::Float32x2.size(),
+                        format: wgpu::VertexFormat::Float32,
+                        shader_location: 5,
+                    },
+                    // target_height
+                    wgpu::VertexAttribute {
+                        offset: 1 * wgpu::VertexFormat::Float32x2.size()
+                            + wgpu::VertexFormat::Float32.size(),
+                        format: wgpu::VertexFormat::Float32,
+                        shader_location: 6,
+                    },
+                    // debug_color
+                    wgpu::VertexAttribute {
+                        offset: 1 * wgpu::VertexFormat::Float32x2.size()
+                            + 2* wgpu::VertexFormat::Float32.size(),
+                        format: wgpu::VertexFormat::Float32x4,
+                        shader_location: 7,
+                    },
+                ],
             },
         ],
     );

src/render/shaders/tile_mask.fragment.wgsl

@@ -1,9 +1,8 @@
-
 struct Output {
     [[location(0)]] out_color: vec4<f32>;
 };
 
 [[stage(fragment)]]
-fn main() -> Output {
+fn main([[location(0)]] v_color: vec4<f32>) -> Output {
-    return Output(vec4<f32>(1.0,1.0,1.0,1.0));
+    return Output(v_color);
 }

src/render/shaders/tile_mask.vertex.wgsl

@@ -11,6 +11,7 @@ struct GlobalsUniform {
 [[group(0), binding(0)]] var<uniform> globals: GlobalsUniform;
 
 struct VertexOutput {
+    [[location(0)]] v_color: vec4<f32>;
     [[builtin(position)]] position: vec4<f32>;
 };
 
@@ -18,19 +19,23 @@ struct VertexOutput {
 fn main(
     [[location(0)]] a_position: vec2<f32>,
     [[location(4)]] mask_offset: vec2<f32>,
+    [[location(5)]] target_width: f32,
+    [[location(6)]] target_height: f32,
+    [[location(7)]] debug_color: vec4<f32>,
     [[builtin(instance_index)]] instance_idx: u32 // instance_index is used when we have multiple instances of the same "object"
 ) -> VertexOutput {
     var z = 0.0;
 
-    var world_pos = a_position + mask_offset;
+    var m: mat3x3<f32> = mat3x3<f32>(
+            target_width,   0.0,            0.0,
+            0.0,            target_height,  0.0,
+            0.0,            0.0,            1.0
+    );
 
-    if (instance_idx == u32(1)) {
+    var world_pos_3d = vec3<f32>(a_position + mask_offset, z);
-        if (a_position.x == 0.0) {
+    var world_pos = m * world_pos_3d;
-            world_pos.x = 0.0;
-        }
-    }
 
-    var position = globals.camera.view_proj * vec4<f32>(world_pos, z, 1.0);
+    var position = globals.camera.view_proj * vec4<f32>(world_pos, 1.0);
 
-    return VertexOutput(position);
+    return VertexOutput(debug_color, position);
 }

src/render/state.rs

@@ -247,8 +247,22 @@ impl State {
             });
 
         let instances = [
-            GpuVertexUniform::new([0.0, 0.0], [0.0, 0.0], 0),
+            // Step 1
-            GpuVertexUniform::new([4096.0, 0.0], [0.0, 0.0], 0),
+            MaskInstanceUniform::new([0.0, 0.0], 4.0, 1.0, [1.0, 0.0, 0.0, 1.0]), // horizontal
+            MaskInstanceUniform::new([0.0, 2.0 * 4096.0], 4.0, 1.0, [1.0, 0.0, 0.0, 1.0]), // vertical
+            // Step 2
+            MaskInstanceUniform::new([1.0 * 4096.0, 0.0], 1.0, 4.0, [0.0, 0.0, 1.0, 1.0]), // vertical
+            MaskInstanceUniform::new([0.0, 1.0 * 4096.0], 4.0, 1.0, [0.0, 0.0, 1.0, 1.0]), // horizontal
+            MaskInstanceUniform::new([3.0 * 4096.0, 0.0], 1.0, 4.0, [0.0, 0.0, 1.0, 1.0]), // vertical
+            MaskInstanceUniform::new([0.0, 3.0 * 4096.0], 4.0, 1.0, [0.0, 0.0, 1.0, 1.0]), // horizontal
+            // Step 3
+            MaskInstanceUniform::new([0.0, 1.0 * 4096.0], 4.0, 1.0, [0.0, 1.0, 0.0, 1.0]), // horizontal
+            MaskInstanceUniform::new([0.0, 3.0 * 4096.0], 4.0, 1.0, [0.0, 1.0, 0.0, 1.0]), // horizontal
+            // Step 4
+            MaskInstanceUniform::new([0.0, 1.0 * 4096.0], 1.0, 1.0, [0.0, 1.0, 1.0, 1.0]), // horizontal
+            MaskInstanceUniform::new([0.0, 3.0 * 4096.0], 1.0, 1.0, [0.0, 1.0, 1.0, 1.0]), // horizontal
+            MaskInstanceUniform::new([2.0 * 4096.0, 1.0 * 4096.0], 1.0, 1.0, [0.0, 1.0, 1.0, 1.0]), // horizontal
+            MaskInstanceUniform::new([2.0 * 4096.0, 3.0 * 4096.0], 1.0, 1.0, [0.0, 1.0, 1.0, 1.0]), // horizontal
         ];
 
         let tile_mask_instances = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
@@ -356,10 +370,6 @@ impl State {
         let render_pipeline = device.create_render_pipeline(&render_pipeline_descriptor);
         let mask_pipeline = device.create_render_pipeline(&mask_pipeline_descriptor);
 
-        // TODO: this isn't what we want: we'd need the equivalent of VK_POLYGON_MODE_LINE,
-        // but it doesn't seem to be exposed by wgpu?
-        //render_pipeline_descriptor.primitive.topology = wgpu::PrimitiveTopology::LineList;
-
         let surface_config = wgpu::SurfaceConfiguration {
             usage: wgpu::TextureUsages::RENDER_ATTACHMENT,
             format: COLOR_TEXTURE_FORMAT,
@@ -540,7 +550,7 @@ impl State {
             pass.set_bind_group(0, &self.bind_group, &[]);
 
             {
-                // Increment stencil
+                // Draw Mask
                 pass.set_pipeline(&self.mask_pipeline);
                 pass.set_index_buffer(
                     self.tile_mask_indices_uniform_buffer.slice(..),
@@ -548,11 +558,11 @@ impl State {
                 );
                 pass.set_vertex_buffer(0, self.tile_mask_vertex_uniform_buffer.slice(..));
                 pass.set_vertex_buffer(1, self.tile_mask_instances.slice(..));
-                pass.draw_indexed(self.tile_mask_range.clone(), 0, 0..2);
+                pass.draw_indexed(self.tile_mask_range.clone(), 0, 0..12);
             }
             {
                 pass.set_pipeline(&self.render_pipeline);
-                pass.set_stencil_reference(2);
+                pass.set_stencil_reference(1);
                 pass.set_index_buffer(self.indices_uniform_buffer.slice(..), INDEX_FORMAT);
                 pass.set_vertex_buffer(0, self.vertex_uniform_buffer.slice(..));
                 if !self.tile_fill_range.is_empty() {
@@ -562,7 +572,7 @@ impl State {
             }
             {
                 pass.set_pipeline(&self.render_pipeline);
-                pass.set_stencil_reference(1);
+                pass.set_stencil_reference(2);
                 pass.set_index_buffer(self.indices_uniform_buffer.slice(..), INDEX_FORMAT);
                 pass.set_vertex_buffer(0, self.vertex_uniform_buffer.slice(..));
                 if !self.tile2_fill_range.is_empty() {