procedural-3d-engine/shaders/slang/viewportarray/scene.slang
2025-05-03 11:11:43 +02:00

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/* Copyright (c) 2025, Sascha Willems
*
* SPDX-License-Identifier: MIT
*
*/
struct VSInput
{
float3 Pos;
float3 Normal;
float3 Color;
};
struct VSOutput
{
float4 Pos : SV_POSITION;
float3 Normal;
float3 Color;
};
struct GSOutput
{
float4 Pos : SV_POSITION;
uint ViewportIndex : SV_ViewportArrayIndex;
uint PrimitiveID : SV_PrimitiveID;
float3 Normal;
float3 Color;
float3 ViewVec;
float3 LightVec;
}
struct UBO
{
float4x4 projection[2];
float4x4 modelview[2];
float4 lightPos;
};
ConstantBuffer<UBO> ubo;
[shader("vertex")]
VSOutput vertexMain(VSInput input)
{
VSOutput output;
output.Color = input.Color;
output.Normal = input.Normal;
output.Pos = float4(input.Pos.xyz, 1.0);
return output;
}
[shader("geometry")]
[maxvertexcount(3)]
[instance(2)]
void geometryMain(triangle VSOutput input[3], inout TriangleStream<GSOutput> outStream, uint InvocationID: SV_GSInstanceID, uint PrimitiveID: SV_PrimitiveID)
{
for (int i = 0; i < 3; i++)
{
GSOutput output;
output.Normal = mul((float3x3)ubo.modelview[InvocationID], input[i].Normal);
output.Color = input[i].Color;
float4 pos = input[i].Pos;
float4 worldPos = mul(ubo.modelview[InvocationID], pos);
float3 lPos = mul(ubo.modelview[InvocationID], ubo.lightPos).xyz;
output.LightVec = lPos - worldPos.xyz;
output.ViewVec = -worldPos.xyz;
output.Pos = mul(ubo.projection[InvocationID], worldPos);
// Set the viewport index that the vertex will be emitted to
output.ViewportIndex = InvocationID;
output.PrimitiveID = PrimitiveID;
outStream.Append(output);
}
outStream.RestartStrip();
}
[shader("fragment")]
float4 fragmentMain(GSOutput input)
{
float3 N = normalize(input.Normal);
float3 L = normalize(input.LightVec);
float3 V = normalize(input.ViewVec);
float3 R = reflect(-L, N);
float3 ambient = float3(0.1, 0.1, 0.1);
float3 diffuse = max(dot(N, L), 0.0) * float3(1.0, 1.0, 1.0);
float3 specular = pow(max(dot(R, V), 0.0), 16.0) * float3(0.75, 0.75, 0.75);
return float4((ambient + diffuse) * input.Color.rgb + specular, 1.0);
}