oglc/shader/include/lighting.glsl

40 lines
1.0 KiB
GLSL

mat3 getTangentSpace(vec3 normal)
{
vec3 helper = abs(normal.x) > 0.99
? vec3(1.0,0.0,0.0)
: vec3(0.0,0.0,1.0);
vec3 tangent = normalize(cross(normal, helper));
vec3 binormal = normalize(cross(normal, tangent));
return mat3(tangent, binormal, normal);
}
vec3 sampleHemisphere(vec3 normal)
{
vec2 uv = pixelUv();
uv += _seed.xy;
vec4 noise = sampleNoise(uv);;
float cosTheta = random(normalize(normal.xy+noise.xy));
float sinTheta = sqrt(max(0.0,1.0-cosTheta*cosTheta));
float phi = 2.0*PI*random(normalize(normal.yz+noise.xw));
vec3 tangentSpaceDir = vec3(cos(phi)*sinTheta, sin(phi)*sinTheta, cosTheta);
// convert direction from tangent space to world space
mat3 ts = getTangentSpace(normal);
return ts * tangentSpaceDir;
}
vec3 scatterLambert(inout Ray ray, RayHit hit)
{
ray.origin = hit.position + hit.normal*0.001;
ray.direction = sampleHemisphere(hit.normal);
ray.energy *= 2.0 * hit.albedo * sdot(hit.normal, ray.direction);
return vec3(0.0);
}