//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK): -task -output-using-type -dx12 -profile sm_6_6 -render-features mesh-shader
//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK): -task -output-using-type -vk -profile sm_6_5 -render-features mesh-shader
//TEST:SIMPLE(filecheck=HLSL):-target hlsl -entry meshMain -stage mesh
//TEST:SIMPLE(filecheck=CHECK_SPV):-target spirv -entry taskMain -stage amplification

// CHECK_SPV: OpEntryPoint
// CHECK_SPV: TaskPayloadWorkgroupEXT


// To test a simple mesh shader, we'll generate 4 triangles, the vertices of
// each one will hold the triangle index and a value (the square). The fragment
// shader will write the value to the specified index of the output buffer.

// CHECK:      0
// CHECK-NEXT: 1
// CHECK-NEXT: 8
// CHECK-NEXT: 27

//TEST_INPUT: ubuffer(data=[0 0 0 0], stride=4):out,name outputBuffer

RWStructuredBuffer<float> outputBuffer;

cbuffer Uniforms
{
	float4x4 modelViewProjection;
}

//
// Task shader
//

struct MeshPayload
{
    int exponent;
};

const static uint AMPLIFICATION_NUM_THREADS_X = 1;

[numthreads(AMPLIFICATION_NUM_THREADS_X, 1, 1)]
[shader("amplification")]
void taskMain(in uint tig : SV_GroupIndex)
{
    MeshPayload p;
    p.exponent = select(AMPLIFICATION_NUM_THREADS_X == WorkgroupSize().x, 3, 0);
    DispatchMesh(1,1,1,p);
}


//
// Mesh shader
//

const static float2 positions[3] = {
  float2(0.0, -0.5),
  float2(0.5, 0.5),
  float2(-0.5, 0.5)
};

const static float3 colors[3] = {
  float3(1.0, 1.0, 0.0),
  float3(0.0, 1.0, 1.0),
  float3(1.0, 0.0, 1.0)
};

struct Vertex
{
  float4 pos : SV_Position;
  float3 color : Color;
  int index : Index;
  int value : Value;
};

const static uint MAX_VERTS = 12;
const static uint MAX_PRIMS = 4;

const static uint MESH_NUM_THREADS_X = 12;

[outputtopology("triangle")]
[numthreads(MESH_NUM_THREADS_X, 1, 1)]
void meshMain(
    in uint tig : SV_GroupIndex,
    in payload MeshPayload meshPayload,
    // Check that we correctly generate the specific 'in payload' that HLSL
    // requires:
    // HLSL: , in payload MeshPayload
    OutputVertices<Vertex, MAX_VERTS> verts,
    OutputIndices<uint3, MAX_PRIMS> triangles)
{
    const uint numVertices = 12;
    const uint numPrimitives = 4;
    SetMeshOutputCounts(numVertices, numPrimitives);

    if(tig < numVertices)
    {
        const int tri = select(WorkgroupSize().x == MESH_NUM_THREADS_X, tig / 3, -1);
        verts[tig] = {float4(positions[tig % 3], 0, 1), colors[tig % 3], tri, int(pow(tri, meshPayload.exponent))};
    }

    if(tig < numPrimitives)
        triangles[tig] = tig * 3 + uint3(0,1,2);
}

//
// Fragment Shader
//

struct Fragment
{
    float4 color : SV_Target;
};

Fragment fragmentMain(Vertex input)
{
	outputBuffer[input.index] = input.value;

	Fragment output;
	output.color = float4(input.color, 1.0);
	return output;
}