Add shapes and basic selective actions

src/shaders/shape.wgsl

@@ -0,0 +1,45 @@
+struct VsUniform {
+    mvp: mat4x4f,
+};
+
+struct ShapeUniform {
+    transform: mat4x4f,
+    base_color: vec4f,
+    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 = vec4f(input.position.x, input.position.y, 0.0, 1.0) * shape_uniform.transform;
+    output.pos = world_pos * vs_uniforms.mvp;
+    if (shape_uniform.state == 2u) {
+        output.color = vec4f(1.0, 0.84, 0.0, 1.0);
+    } else if (shape_uniform.state == 1u) {
+        output.color = clamp(shape_uniform.base_color * 1.5, vec4f(0.0), vec4f(1.0));
+    } else {
+        output.color = shape_uniform.base_color;
+    }
+    return output;
+}
+
+@fragment fn fs_main(input: Vs2Fs) -> FsOut {
+    var output: FsOut;
+    output.color = input.color;
+    return output;
+}