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[vertex]
layout(location=0) in highp vec4 vertex_attrib;
void main() {
gl_Position = vertex_attrib;
}
[fragment]
#ifdef MINIFY_START
#define SDEPTH_TYPE highp sampler2D
uniform float camera_z_far;
uniform float camera_z_near;
#else
#define SDEPTH_TYPE mediump usampler2D
#endif
uniform SDEPTH_TYPE source_depth; //texunit:0
uniform ivec2 from_size;
uniform int source_mipmap;
layout(location = 0) out mediump uint depth;
void main() {
ivec2 ssP = ivec2(gl_FragCoord.xy);
// Rotated grid subsampling to avoid XY directional bias or Z precision bias while downsampling.
// On DX9, the bit-and can be implemented with floating-point modulo
#ifdef MINIFY_START
float fdepth = texelFetch(source_depth, clamp(ssP * 2 + ivec2(ssP.y & 1, ssP.x & 1), ivec2(0), from_size - ivec2(1)), source_mipmap).r;
fdepth = fdepth * 2.0 - 1.0;
#ifdef USE_ORTHOGONAL_PROJECTION
fdepth = ((fdepth + (camera_z_far + camera_z_near)/(camera_z_far - camera_z_near)) * (camera_z_far - camera_z_near))/2.0;
#else
fdepth = 2.0 * camera_z_near * camera_z_far / (camera_z_far + camera_z_near - fdepth * (camera_z_far - camera_z_near));
#endif
fdepth /= camera_z_far;
depth = uint(clamp(fdepth*65535.0,0.0,65535.0));
#else
depth = texelFetch(source_depth, clamp(ssP * 2 + ivec2(ssP.y & 1, ssP.x & 1), ivec2(0), from_size - ivec2(1)), source_mipmap).r;
#endif
}
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