100 lines
2.0 KiB
Bash
100 lines
2.0 KiB
Bash
#include "bgfx_compute.sh"
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#include "matrices.sh"
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#include "isubd.sh"
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#include "uniforms.sh"
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BUFFER_RW(u_AtomicCounterBuffer, uint, 4);
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BUFFER_RW(u_SubdBufferOut, uint, 1);
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SAMPLER2D(u_DmapSampler, 0); // displacement map
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SAMPLER2D(u_SmapSampler, 1); // slope map
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// displacement map
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float dmap(vec2 pos)
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{
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return (texture2DLod(u_DmapSampler, pos * 0.5 + 0.5, 0).x) * u_DmapFactor;
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}
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float distanceToLod(float z, float lodFactor)
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{
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// Note that we multiply the result by two because the triangles
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// edge lengths decreases by half every two subdivision steps.
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return -2.0 * log2(clamp(z * lodFactor, 0.0f, 1.0f));
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}
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float computeLod(vec3 c)
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{
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//displace
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c.z += dmap(mtxGetColumn(u_invView, 3).xy);
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vec3 cxf = mul(u_modelView, vec4(c.x, c.y, c.z, 1)).xyz;
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float z = length(cxf);
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return distanceToLod(z, u_LodFactor);
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}
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float computeLod(in vec4 v[3])
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{
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vec3 c = (v[1].xyz + v[2].xyz) / 2.0;
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return computeLod(c);
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}
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float computeLod(in vec3 v[3])
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{
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vec3 c = (v[1].xyz + v[2].xyz) / 2.0;
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return computeLod(c);
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}
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void writeKey(uint primID, uint key)
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{
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uint idx = 0;
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atomicFetchAndAdd(u_AtomicCounterBuffer[0], 2, idx);
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u_SubdBufferOut[idx] = primID;
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u_SubdBufferOut[idx+1] = key;
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}
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void updateSubdBuffer(
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uint primID
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, uint key
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, uint targetLod
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, uint parentLod
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, bool isVisible
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)
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{
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// extract subdivision level associated to the key
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uint keyLod = findMSB(key);
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// update the key accordingly
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if (/* subdivide ? */ keyLod < targetLod && !isLeafKey(key) && isVisible)
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{
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uint children[2]; childrenKeys(key, children);
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writeKey(primID, children[0]);
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writeKey(primID, children[1]);
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}
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else if (/* keep ? */ keyLod < (parentLod + 1) && isVisible)
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{
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writeKey(primID, key);
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}
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else /* merge ? */
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{
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if (/* is root ? */isRootKey(key))
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{
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writeKey(primID, key);
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}
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else if (/* is zero child ? */isChildZeroKey(key)) {
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writeKey(primID, parentKey(key));
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}
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}
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}
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void updateSubdBuffer(uint primID, uint key, uint targetLod, uint parentLod)
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{
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updateSubdBuffer(primID, key, targetLod, parentLod, true);
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}
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