56 lines
1.5 KiB
GLSL
56 lines
1.5 KiB
GLSL
// ============================================================================
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// 辐照度贴图生成 - 用于漫反射IBL
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// ============================================================================
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#type vertex
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#version 450 core
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layout(location = 0) in vec3 a_Position;
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out vec3 v_WorldPos;
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uniform mat4 u_Projection;
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uniform mat4 u_View;
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void main() {
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v_WorldPos = a_Position;
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gl_Position = u_Projection * u_View * vec4(a_Position, 1.0);
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}
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#type fragment
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#version 450 core
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out vec4 FragColor;
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in vec3 v_WorldPos;
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uniform samplerCube u_EnvironmentMap;
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const float PI = 3.14159265359;
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void main() {
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vec3 N = normalize(v_WorldPos);
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vec3 irradiance = vec3(0.0);
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vec3 up = vec3(0.0, 1.0, 0.0);
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if(abs(N.y) > 0.999) {
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up = vec3(0.0, 0.0, 1.0);
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}
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vec3 right = normalize(cross(up, N));
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up = normalize(cross(N, right));
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// 在半球上采样
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float sampleDelta = 0.015;
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float nrSamples = 0.0;
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for(float phi = 0.0; phi < 2.0 * PI; phi += sampleDelta) {
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for(float theta = 0.0; theta < 0.5 * PI; theta += sampleDelta) {
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vec3 tangentSample = vec3(sin(theta) * cos(phi), sin(theta) * sin(phi), cos(theta));
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vec3 sampleVec = tangentSample.x * right + tangentSample.y * up + tangentSample.z * N;
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irradiance += texture(u_EnvironmentMap, sampleVec).rgb * cos(theta) * sin(theta);
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nrSamples++;
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}
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}
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irradiance = PI * irradiance * (1.0 / float(nrSamples));
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FragColor = vec4(irradiance, 1.0);
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}
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