procedural-3d-engine/shaders/slang/graphicspipelinelibrary/uber.slang

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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;
float3 ViewVec;
float3 LightVec;
};
struct UBO
{
float4x4 projection;
float4x4 model;
float4 lightPos;
};
ConstantBuffer<UBO> ubo;
// We use this constant to control the flow of the shader depending on the
// lighting model selected at pipeline creation time
[[SpecializationConstant]] const int LIGHTING_MODEL = 0;
[shader("vertex")]
VSOutput vertexMain(VSInput input)
{
VSOutput output;
output.Color = input.Color;
output.Pos = mul(ubo.projection, mul(ubo.model, float4(input.Pos.xyz, 1.0)));
float4 pos = mul(ubo.model, float4(input.Pos, 1.0));
output.Normal = mul((float3x3)ubo.model, input.Normal);
float3 lPos = mul((float3x3)ubo.model, ubo.lightPos.xyz);
output.LightVec = lPos - pos.xyz;
output.ViewVec = -pos.xyz;
return output;
}
[shader("fragment")]
float4 fragmentMain(VSOutput input)
{
float3 outColor = float3(0.0);
switch (LIGHTING_MODEL) {
case 0: // Phong
{
float3 ambient = input.Color * float3(0.25, 0.25, 0.25);
float3 N = normalize(input.Normal);
float3 L = normalize(input.LightVec);
float3 V = normalize(input.ViewVec);
float3 R = reflect(-L, N);
float3 diffuse = max(dot(N, L), 0.0) * input.Color;
float3 specular = pow(max(dot(R, V), 0.0), 32.0) * float3(0.75);
outColor = ambient + diffuse * 1.75 + specular;
break;
}
case 1: // Toon
{
float3 N = normalize(input.Normal);
float3 L = normalize(input.LightVec);
float intensity = dot(N, L);
float3 color;
if (intensity > 0.98)
color = input.Color * 1.5;
else if (intensity > 0.9)
color = input.Color * 1.0;
else if (intensity > 0.5)
color = input.Color * 0.6;
else if (intensity > 0.25)
color = input.Color * 0.4;
else
color = input.Color * 0.2;
outColor = color;
break;
}
case 2: // No shading
{
outColor = input.Color;
break;
}
case 3: // Greyscale
outColor = dot(input.Color, float3(0.299, 0.587, 0.114));
break;
}
// The scene itself is a bit dark, so brigthen it up a bit
return float4(outColor * 1.25, 1.0);
}