Complete rework of the sample

Simplified, added comments and only use single buffers to show best practices

shaders/hlsl/gears/gears.vert

@@ -1,4 +1,5 @@
 // Copyright 2020 Google LLC
+// Copyright 2023 Sascha Willems
 
 struct VSInput
 {
@@ -10,10 +11,9 @@ struct VSInput
 struct UBO
 {
 	float4x4 projection;
-	float4x4 model;
-	float4x4 normal;
 	float4x4 view;
-	float3 lightpos;
+	float4 lightpos;
+	float4x4 model[3];
 };
 
 cbuffer ubo : register(b0) { UBO ubo; }
@@ -27,15 +27,15 @@ struct VSOutput
 [[vk::location(3)]] float3 LightVec : TEXCOORD2;
 };
 
-VSOutput main(VSInput input)
+VSOutput main(VSInput input, uint InstanceIndex : SV_InstanceID)
 {
 	VSOutput output = (VSOutput)0;
-	output.Normal = normalize(mul((float4x3)ubo.normal, input.Normal).xyz);
+	output.Normal = normalize(mul((float3x3)transpose(ubo.model[InstanceIndex]), input.Normal).xyz);
 	output.Color = input.Color;
-	float4x4 modelView = mul(ubo.view, ubo.model);
+	float4x4 modelView = mul(ubo.view, ubo.model[InstanceIndex]);
 	float4 pos = mul(modelView, input.Pos);
 	output.EyePos = mul(modelView, pos).xyz;
-	float4 lightPos = mul(float4(ubo.lightpos, 1.0), modelView);
+	float4 lightPos = mul(float4(ubo.lightpos.xyz, 1.0), modelView);
 	output.LightVec = normalize(lightPos.xyz - output.EyePos);
 	output.Pos = mul(ubo.projection, pos);
 	return output;