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layout(std140) uniform shadow_render_block {
mat4 ShadowMatrix[6];
mat4 FaceViewMatrix[6];
vec4 lampPosition;
float cubeTexelSize;
float storedTexelSize;
float nearClip;
float farClip;
int shadowSampleCount;
float shadowInvSampleCount;
};
#ifdef CSM
uniform sampler2DArray shadowTexture;
uniform int cascadeId;
#else
uniform samplerCube shadowTexture;
#endif
uniform float shadowFilterSize;
out vec4 FragColor;
vec3 octahedral_to_cubemap_proj(vec2 co)
{
co = co * 2.0 - 1.0;
vec2 abs_co = abs(co);
vec3 v = vec3(co, 1.0 - (abs_co.x + abs_co.y));
if ( abs_co.x + abs_co.y > 1.0 ) {
v.xy = (abs(co.yx) - 1.0) * -sign(co.xy);
}
return v;
}
/* Marco Salvi's GDC 2008 presentation about shadow maps pre-filtering techniques slide 24 */
float ln_space_prefilter(float w0, float x, float w1, float y)
{
return x + log(w0 + w1 * exp(y - x));
}
vec4 ln_space_prefilter(float w0, vec4 x, float w1, vec4 y)
{
return x + log(w0 + w1 * exp(y - x));
}
#ifdef CSM
vec3 get_texco(vec3 cos, vec2 ofs)
{
cos.xy += ofs * shadowFilterSize;
return cos;
}
#else /* CUBEMAP */
/* global vars */
vec3 T = vec3(0.0);
vec3 B = vec3(0.0);
void make_orthonormal_basis(vec3 N)
{
vec3 UpVector = (abs(N.z) < 0.999) ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);
T = normalize(cross(UpVector, N));
B = cross(N, T);
}
vec3 get_texco(vec3 cos, vec2 ofs)
{
return cos + ofs.x * T + ofs.y * B;
}
#endif
void main() {
vec3 cos;
cos.xy = gl_FragCoord.xy * storedTexelSize;
#ifdef CSM
cos.z = float(cascadeId);
#else /* CUBEMAP */
/* add a 2 pixel border to ensure filtering is correct */
cos.xy *= 1.0 + storedTexelSize * 2.0;
cos.xy -= storedTexelSize;
float pattern = 1.0;
/* edge mirroring : only mirror if directly adjacent
* (not diagonally adjacent) */
vec2 m = abs(cos.xy - 0.5) + 0.5;
vec2 f = floor(m);
if (f.x - f.y != 0.0) {
cos.xy = 1.0 - cos.xy;
}
/* clamp to [0-1] */
cos.xy = fract(cos.xy);
/* get cubemap vector */
cos = normalize(octahedral_to_cubemap_proj(cos.xy));
make_orthonormal_basis(cos);
T *= shadowFilterSize;
B *= shadowFilterSize;
#endif
#ifdef ESM
vec4 accum = vec4(0.0);
/* disc blur in log space. */
vec4 depths;
depths.x = texture(shadowTexture, get_texco(cos, concentric[0])).r;
depths.y = texture(shadowTexture, get_texco(cos, concentric[1])).r;
depths.z = texture(shadowTexture, get_texco(cos, concentric[2])).r;
depths.w = texture(shadowTexture, get_texco(cos, concentric[3])).r;
accum = ln_space_prefilter(0.0, accum, shadowInvSampleCount, depths);
for (int i = 4; i < shadowSampleCount && i < CONCENTRIC_SAMPLE_NUM; i += 4) {
depths.x = texture(shadowTexture, get_texco(cos, concentric[i+0])).r;
depths.y = texture(shadowTexture, get_texco(cos, concentric[i+1])).r;
depths.z = texture(shadowTexture, get_texco(cos, concentric[i+2])).r;
depths.w = texture(shadowTexture, get_texco(cos, concentric[i+3])).r;
accum = ln_space_prefilter(1.0, accum, shadowInvSampleCount, depths);
}
accum.x = ln_space_prefilter(1.0, accum.x, 1.0, accum.y);
accum.x = ln_space_prefilter(1.0, accum.x, 1.0, accum.z);
accum.x = ln_space_prefilter(1.0, accum.x, 1.0, accum.w);
FragColor = accum.xxxx;
#else /* VSM */
vec2 accum = vec2(0.0);
/* disc blur. */
vec4 depths1, depths2;
for (int i = 0; i < shadowSampleCount && i < CONCENTRIC_SAMPLE_NUM; i += 4) {
depths1.xy = texture(shadowTexture, get_texco(cos, concentric[i+0])).rg;
depths1.zw = texture(shadowTexture, get_texco(cos, concentric[i+1])).rg;
depths2.xy = texture(shadowTexture, get_texco(cos, concentric[i+2])).rg;
depths2.zw = texture(shadowTexture, get_texco(cos, concentric[i+3])).rg;
accum += depths1.xy + depths1.zw + depths2.xy + depths2.zw;
}
FragColor = accum.xyxy * shadowInvSampleCount;
#endif
}
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