116 lines
3.1 KiB
Python
116 lines
3.1 KiB
Python
/*
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* Copyright 2018 Kostas Anagnostou. All rights reserved.
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* License: https://github.com/bkaradzic/bgfx#license-bsd-2-clause
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*/
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#include "bgfx_compute.sh"
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SAMPLER2D(s_texOcclusionDepth, 0);
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BUFFER_RO(instanceDataIn, vec4, 1);
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BUFFER_RW(drawcallInstanceCount, uint, 2);
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BUFFER_WR(instancePredicates, bool, 3);
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uniform vec4 u_inputRTSize;
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uniform vec4 u_cullingConfig;
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NUM_THREADS(64, 1, 1)
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void main()
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{
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bool predicate = false;
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//make sure that we not processing more instances than available
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if (gl_GlobalInvocationID.x < uint(u_cullingConfig.x) )
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{
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//get the bounding box for this instance
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vec4 bboxMin = instanceDataIn[2 * gl_GlobalInvocationID.x] ;
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vec3 bboxMax = instanceDataIn[2 * gl_GlobalInvocationID.x + 1].xyz;
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int drawcallID = int(bboxMin.w);
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//Adapted from http://blog.selfshadow.com/publications/practical-visibility/
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vec3 bboxSize = bboxMax.xyz - bboxMin.xyz;
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vec3 boxCorners[] = {
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bboxMin.xyz,
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bboxMin.xyz + vec3(bboxSize.x,0,0),
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bboxMin.xyz + vec3(0, bboxSize.y,0),
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bboxMin.xyz + vec3(0, 0, bboxSize.z),
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bboxMin.xyz + vec3(bboxSize.xy,0),
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bboxMin.xyz + vec3(0, bboxSize.yz),
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bboxMin.xyz + vec3(bboxSize.x, 0, bboxSize.z),
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bboxMin.xyz + bboxSize.xyz
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};
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float minZ = 1.0;
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vec2 minXY = vec2(1.0, 1.0);
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vec2 maxXY = vec2(0.0, 0.0);
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UNROLL
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for (int i = 0; i < 8; i++)
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{
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//transform World space aaBox to NDC
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vec4 clipPos = mul( u_viewProj, vec4(boxCorners[i], 1) );
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#if BGFX_SHADER_LANGUAGE_GLSL
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clipPos.z = 0.5 * ( clipPos.z + clipPos.w );
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#endif
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clipPos.z = max(clipPos.z, 0);
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clipPos.xyz = clipPos.xyz / clipPos.w;
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clipPos.xy = clamp(clipPos.xy, -1, 1);
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clipPos.xy = clipPos.xy * vec2(0.5, -0.5) + vec2(0.5, 0.5);
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minXY = min(clipPos.xy, minXY);
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maxXY = max(clipPos.xy, maxXY);
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minZ = saturate(min(minZ, clipPos.z));
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}
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vec4 boxUVs = vec4(minXY, maxXY);
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// Calculate hi-Z buffer mip
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ivec2 size = ivec2( (maxXY - minXY) * u_inputRTSize.xy);
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float mip = ceil(log2(max(size.x, size.y)));
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mip = clamp(mip, 0, u_cullingConfig.z);
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// Texel footprint for the lower (finer-grained) level
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float level_lower = max(mip - 1, 0);
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vec2 scale = vec2_splat(exp2(-level_lower) );
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vec2 a = floor(boxUVs.xy*scale);
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vec2 b = ceil(boxUVs.zw*scale);
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vec2 dims = b - a;
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// Use the lower level if we only touch <= 2 texels in both dimensions
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if (dims.x <= 2 && dims.y <= 2)
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mip = level_lower;
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#if BGFX_SHADER_LANGUAGE_GLSL
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boxUVs.y = 1.0 - boxUVs.y;
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boxUVs.w = 1.0 - boxUVs.w;
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#endif
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//load depths from high z buffer
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vec4 depth =
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{
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texture2DLod(s_texOcclusionDepth, boxUVs.xy, mip).x,
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texture2DLod(s_texOcclusionDepth, boxUVs.zy, mip).x,
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texture2DLod(s_texOcclusionDepth, boxUVs.xw, mip).x,
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texture2DLod(s_texOcclusionDepth, boxUVs.zw, mip).x,
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};
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//find the max depth
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float maxDepth = max( max(depth.x, depth.y), max(depth.z, depth.w) );
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if ( minZ <= maxDepth )
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{
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predicate = true;
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//increase instance count for this particular prop type
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atomicAdd(drawcallInstanceCount[ drawcallID ], 1);
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}
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}
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instancePredicates[gl_GlobalInvocationID.x] = predicate;
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}
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