Add copy/paste, rewrite rendering pipeline with instanced draw calls and add a lot of caching to minimize overhead on huge edits.

src/shaders/overlay.wgsl

@@ -0,0 +1,44 @@
+struct VsUniform {
+    mvp: mat4x4f,
+};
+
+struct ShapeUniform {
+    transform: mat4x4f,
+    state: u32,
+};
+
+struct VsIn {
+    @location(0) position: vec2f,
+};
+
+struct Vs2Fs {
+    @builtin(position) pos: vec4f,
+    @location(0) @interpolate(linear) color: vec4f,
+};
+
+struct FsOut {
+    @location(0) color: vec4f,
+};
+
+@binding(0) @group(0) var<uniform> vs_uniforms: VsUniform;
+@binding(1) @group(0) var<uniform> shape_uniform: ShapeUniform;
+
+@vertex fn vs_main(input: VsIn) -> Vs2Fs {
+    var output: Vs2Fs;
+    let world_pos = shape_uniform.transform * vec4f(input.position.x, input.position.y, 0.0, 1.0);
+    output.pos = vs_uniforms.mvp * world_pos;
+    if (shape_uniform.state == 2u) {
+        output.color = vec4f(1.0, 0.84, 0.0, 1.0);
+    } else if (shape_uniform.state == 1u) {
+        output.color = vec4f(0.5, 0.6, 1.0, 1.0);
+    } else {
+        output.color = vec4f(0.8, 0.8, 0.8, 1.0);
+    }
+    return output;
+}
+
+@fragment fn fs_main(input: Vs2Fs) -> FsOut {
+    var output: FsOut;
+    output.color = input.color;
+    return output;
+}

src/shaders/shape.wgsl

@@ -1,13 +1,20 @@
 struct VsUniform {
     mvp: mat4x4f,
+    instance_base: u32,
 };
 
-struct ShapeUniform {
+struct ShapeData {
     transform: mat4x4f,
     state: u32,
 };
 
+@binding(0) @group(0) var<uniform> vs_uniforms: VsUniform;
+
+@binding(0) @group(1) var<storage> shape_data: array<ShapeData>;
+@binding(1) @group(1) var<storage> instance_map: array<u32>;
+
 struct VsIn {
+    @builtin(instance_index) instance_idx: u32,
     @location(0) position: vec2f,
 };
 
@@ -20,16 +27,15 @@ struct FsOut {
     @location(0) color: vec4f,
 };
 
-@binding(0) @group(0) var<uniform> vs_uniforms: VsUniform;
-@binding(1) @group(0) var<uniform> shape_uniform: ShapeUniform;
-
 @vertex fn vs_main(input: VsIn) -> Vs2Fs {
     var output: Vs2Fs;
-    let world_pos = shape_uniform.transform * vec4f(input.position.x, input.position.y, 0.0, 1.0);
+    let shape_idx = instance_map[vs_uniforms.instance_base + input.instance_idx];
+    let shape = shape_data[shape_idx];
+    let world_pos = shape.transform * vec4f(input.position.x, input.position.y, 0.0, 1.0);
     output.pos = vs_uniforms.mvp * world_pos;
-    if (shape_uniform.state == 2u) {
+    if (shape.state == 2u) {
         output.color = vec4f(1.0, 0.84, 0.0, 1.0);
-    } else if (shape_uniform.state == 1u) {
+    } else if (shape.state == 1u) {
         output.color = vec4f(0.5, 0.6, 1.0, 1.0);
     } else {
         output.color = vec4f(0.8, 0.8, 0.8, 1.0);