procedural-3d-engine/shaders/slang/variablerateshading/scene.slang
2025-05-10 13:58:14 +02:00

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/* Copyright (c) 2025, Sascha Willems
*
* SPDX-License-Identifier: MIT
*
*/
struct VSInput
{
float3 Pos;
float3 Normal;
float2 UV;
float3 Color;
float4 Tangent;
};
struct VSOutput
{
float4 Pos : SV_POSITION;
float3 Normal;
float3 Color;
float2 UV;
float3 ViewVec;
float3 LightVec;
float4 Tangent;
};
struct UBO
{
float4x4 projection;
float4x4 view;
float4x4 model;
float4 lightPos;
float4 viewPos;
int colorShadingRates;
};
ConstantBuffer<UBO> ubo;
[[vk::binding(0, 1)]] Sampler2D samplerColorMap;
[[vk::binding(1, 1)]] Sampler2D samplerNormalMap;
[[SpecializationConstant]] const bool ALPHA_MASK = false;
[[SpecializationConstant]] const float ALPHA_MASK_CUTOFF = 0.0;
[shader("vertex")]
VSOutput vertexMain(VSInput input)
{
VSOutput output;
output.Normal = input.Normal;
output.Color = input.Color;
output.UV = input.UV;
output.Tangent = input.Tangent;
float4x4 modelView = mul(ubo.view, ubo.model);
output.Pos = mul(ubo.projection, mul(modelView, float4(input.Pos.xyz, 1.0)));
output.Normal = mul((float3x3)ubo.model, input.Normal);
float4 pos = mul(ubo.model, float4(input.Pos, 1.0));
output.LightVec = ubo.lightPos.xyz - pos.xyz;
output.ViewVec = ubo.viewPos.xyz - pos.xyz;
return output;
}
static const uint SHADING_RATE_PER_PIXEL = 0;
static const uint SHADING_RATE_PER_2X1_PIXELS = 6;
static const uint SHADING_RATE_PER_1X2_PIXELS = 7;
static const uint SHADING_RATE_PER_2X2_PIXELS = 8;
static const uint SHADING_RATE_PER_4X2_PIXELS = 9;
static const uint SHADING_RATE_PER_2X4_PIXELS = 10;
[shader("fragment")]
float4 fragmentMain(VSOutput input, uint shadingRate : SV_ShadingRate)
{
float4 color = samplerColorMap.Sample(input.UV) * float4(input.Color, 1.0);
if (ALPHA_MASK) {
if (color.a < ALPHA_MASK_CUTOFF) {
discard;
}
}
float3 N = normalize(input.Normal);
float3 T = normalize(input.Tangent.xyz);
float3 B = cross(input.Normal, input.Tangent.xyz) * input.Tangent.w;
float3x3 TBN = float3x3(T, B, N);
N = mul(normalize(samplerNormalMap.Sample(input.UV).xyz * 2.0 - float3(1.0, 1.0, 1.0)), TBN);
const float ambient = 0.1;
float3 L = normalize(input.LightVec);
float3 V = normalize(input.ViewVec);
float3 R = reflect(-L, N);
float3 diffuse = max(dot(N, L), ambient).rrr;
float3 specular = pow(max(dot(R, V), 0.0), 32.0);
color = float4(diffuse * color.rgb + specular, color.a);
if (ubo.colorShadingRates == 1) {
switch (shadingRate) {
case SHADING_RATE_PER_PIXEL:
return color * float4(0.0, 0.8, 0.4, 1.0);
case SHADING_RATE_PER_2X1_PIXELS:
return color * float4(0.2, 0.6, 1.0, 1.0);
case SHADING_RATE_PER_1X2_PIXELS:
return color * float4(0.0, 0.4, 0.8, 1.0);
case SHADING_RATE_PER_2X2_PIXELS:
return color * float4(1.0, 1.0, 0.2, 1.0);
case SHADING_RATE_PER_4X2_PIXELS:
return color * float4(0.8, 0.8, 0.0, 1.0);
case SHADING_RATE_PER_2X4_PIXELS:
return color * float4(1.0, 0.4, 0.2, 1.0);
default:
return color * float4(0.8, 0.0, 0.0, 1.0);
}
}
return color;
}