Initial commit for vulkan tutorial

Following along the first 9 chapters of the Vulkan HelloTriangle
tutorial.

shaders/09_shader_base.slang

@@ -0,0 +1,29 @@
+static float2 positions[3] = float2[](
+  float2( 0.0, -0.5),
+  float2( 0.5,  0.5),
+  float2(-0.5,  0.5),
+);
+
+static float3 colors[3] = float3[](
+  float3(1.0, 0.0, 0.0),
+  float3(0.0, 1.0, 0.0),
+  float3(0.0, 0.0, 1.0),
+);
+
+struct VertexOutput {
+  float3 color;
+  float4 sv_position : SV_Position;
+};
+
+[shader("vertex")]
+VertexOutput vertMain(uint vid : SV_VertexID) {
+  VertexOutput output;
+  output.color       = colors[vid];
+  output.sv_position = float4(positions[vid], 0.0, 1.0);
+  return output;
+}
+
+[shader("fragment")]
+float4 fragMain(VertexOutput inVert) : SV_Target {
+  return float4(inVert.color, 1.0);
+}