procedural-3d-engine/shaders/slang/particlesystem/normalmap.slang
2025-05-20 17:37:27 +02:00

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/* Copyright (c) 2025, Sascha Willems
*
* SPDX-License-Identifier: MIT
*
*/
struct VSInput
{
float3 Pos;
float2 UV;
float3 Normal;
float4 Tangent;
};
struct VSOutput
{
float4 Pos : SV_POSITION;
float2 UV;
float3 LightVec;
float3 LightVecB;
float3 LightDir;
float3 ViewVec;
};
struct UBO
{
float4x4 projection;
float4x4 model;
float4x4 normal;
float4 lightPos;
};
ConstantBuffer<UBO> ubo;
Sampler2D samplerColorMap;
Sampler2D samplerNormalHeightMap;
#define lightRadius 45.0
[shader("vertex")]
VSOutput vertexMain(VSInput input)
{
VSOutput output;
float3 vertexPosition = mul(ubo.model, float4(input.Pos, 1.0)).xyz;
output.LightDir = normalize(ubo.lightPos.xyz - vertexPosition);
float3 biTangent = cross(input.Normal, input.Tangent.xyz);
// Setup (t)angent-(b)inormal-(n)ormal matrix for converting
// object coordinates into tangent space
float3x3 tbnMatrix;
tbnMatrix[0] = mul((float3x3)ubo.normal, input.Tangent.xyz);
tbnMatrix[1] = mul((float3x3)ubo.normal, biTangent);
tbnMatrix[2] = mul((float3x3)ubo.normal, input.Normal);
output.LightVec.xyz = mul(float3(ubo.lightPos.xyz - vertexPosition), tbnMatrix);
float3 lightDist = ubo.lightPos.xyz - input.Pos;
output.LightVecB.x = dot(input.Tangent.xyz, lightDist);
output.LightVecB.y = dot(biTangent, lightDist);
output.LightVecB.z = dot(input.Normal, lightDist);
output.ViewVec.x = dot(input.Tangent.xyz, input.Pos);
output.ViewVec.y = dot(biTangent, input.Pos);
output.ViewVec.z = dot(input.Normal, input.Pos);
output.UV = input.UV;
output.Pos = mul(ubo.projection, mul(ubo.model, float4(input.Pos, 1.0)));
return output;
}
[shader("fragment")]
float4 fragmentMain(VSOutput input)
{
float3 specularColor = float3(0.85, 0.5, 0.0);
float invRadius = 1.0/lightRadius;
float ambient = 0.25;
float3 rgb, normal;
rgb = samplerColorMap.Sample(input.UV).rgb;
normal = normalize((samplerNormalHeightMap.Sample(input.UV).rgb - 0.5) * 2.0);
float distSqr = dot(input.LightVecB, input.LightVecB);
float3 lVec = input.LightVecB * rsqrt(distSqr);
float atten = max(clamp(1.0 - invRadius * sqrt(distSqr), 0.0, 1.0), ambient);
float diffuse = clamp(dot(lVec, normal), 0.0, 1.0);
float3 light = normalize(-input.LightVec);
float3 view = normalize(input.ViewVec);
float3 reflectDir = reflect(-light, normal);
float specular = pow(max(dot(view, reflectDir), 0.0), 4.0);
return float4((rgb * atten + (diffuse * rgb + 0.5 * specular * specularColor.rgb)) * atten, 1.0);
}