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drawmeshlet_ext_scull.mesh.glsl
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drawmeshlet_ext_scull.mesh.glsl
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/*
* Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION
* SPDX-License-Identifier: Apache-2.0
*/
// This shader is currently not used stand-alone
// but used conditionally be `drawmeshlet_ext_cull.mesh.glsl`.
// Though it can be made stand-alone easily.
//
// It is an optimized version of `drawmeshlet_ext_cull.mesh.glsl`
// for the vertex and/or triangle counts being 32 or 64 as well
// as the subgroup size being 32 or 64.
//
// It does not use shared memory, but uses shuffle instead to
// handle re-ordering of data. Such variables will be stored
// in "temp" variables as registers.
#include "config.h"
//////////////////////////////////////
#extension GL_EXT_mesh_shader : require
//////////////////////////////////////
#extension GL_EXT_shader_explicit_arithmetic_types_int8 : require
#extension GL_EXT_shader_explicit_arithmetic_types_int16 : require
#extension GL_EXT_shader_explicit_arithmetic_types_int32 : require
#extension GL_EXT_shader_explicit_arithmetic_types_int64 : require
#extension GL_EXT_shader_subgroup_extended_types_int64 : require
#extension GL_KHR_shader_subgroup_basic : require
#extension GL_KHR_shader_subgroup_ballot : require
#extension GL_KHR_shader_subgroup_vote : require
#extension GL_KHR_shader_subgroup_shuffle : require
#extension GL_KHR_shader_subgroup_arithmetic : require
//////////////////////////////////////
#include "common.h"
//////////////////////////////////////////////////
// MESH CONFIG
#if EXT_MESH_SUBGROUP_COUNT != 1
#error "EXT_MESH_SUBGROUP_COUNT must be 1 in this shader"
#endif
#if !(NVMESHLET_VERTEX_COUNT == 64 || NVMESHLET_VERTEX_COUNT == 32)
#error "NVMESHLET_VERTEX_COUNT must be 32 or 64 in this shader"
#endif
#if !(NVMESHLET_PRIMITIVE_COUNT == 64 || NVMESHLET_PRIMITIVE_COUNT == 32)
#error "NVMESHLET_PRIMITIVE_COUNT must be 32 or 64 in this shader"
#endif
// see Sample::getShaderPrepend() how these are computed
const uint WORKGROUP_SIZE = EXT_MESH_SUBGROUP_COUNT * EXT_MESH_SUBGROUP_SIZE;
layout(local_size_x=WORKGROUP_SIZE) in;
layout(max_vertices=NVMESHLET_VERTEX_COUNT, max_primitives=NVMESHLET_PRIMITIVE_COUNT) out;
layout(triangles) out;
// The workgroup size of the shader may not have enough threads
// to do all the work in a unique thread.
// Therefore we might need to loop to process all the work.
// Looping can have the benefit that we can amortize some registers
// that are common to all threads. However, it may also introduce
// more registers.
const uint MESHLET_VERTEX_ITERATIONS = ((NVMESHLET_VERTEX_COUNT + WORKGROUP_SIZE - 1) / WORKGROUP_SIZE);
const uint MESHLET_PRIMITIVE_ITERATIONS = ((NVMESHLET_PRIMITIVE_COUNT + WORKGROUP_SIZE - 1) / WORKGROUP_SIZE);
// task shader is used in advance, doing early cluster culling
#ifndef USE_TASK_STAGE
#define USE_TASK_STAGE 0
#endif
// set in Sample::getShaderPrepend()
// process vertex outputs after primitive culling
// once we know which vertices are actually used
#ifndef USE_VERTEX_CULL
#define USE_VERTEX_CULL 1
#endif
// do frustum culling if primitive culling is active
// otherwise only backface & subpixel is done
#ifndef USE_MESH_FRUSTUMCULL
#define USE_MESH_FRUSTUMCULL 1
#endif
////////////////////////////////////////////////////////////
// optimize configurations
#if USE_TASK_STAGE
// always disable frustumcull on mesh level
// task stage does the heavy lifting
#undef USE_MESH_FRUSTUMCULL
#define USE_MESH_FRUSTUMCULL 0
#endif
#if (SHOW_PRIMIDS || USE_BARYCENTRIC_SHADING) && (!EXT_COMPACT_VERTEX_OUTPUT)
// no attributes exist in these modes, so disable vertex culling, unless compact is preferred
#undef USE_VERTEX_CULL
#define USE_VERTEX_CULL 0
#endif
// mostly used to detect if no compactiong is active at all, then we will pre-allocate similar to basic shader
#define EXT_USE_ANY_COMPACTION ((USE_VERTEX_CULL && EXT_COMPACT_VERTEX_OUTPUT) || EXT_COMPACT_PRIMITIVE_OUTPUT)
// prefer load into registers, then work with data in separate pass
// should make sense if a single subgroup has to loop
#ifndef USE_EARLY_TOPOLOGY_LOAD
#define USE_EARLY_TOPOLOGY_LOAD ((EXT_MESH_SUBGROUP_COUNT == 1) && (NVMESHLET_PRIMITIVE_COUNT > EXT_MESH_SUBGROUP_SIZE))
#endif
/////////////////////////////////////
// UNIFORMS
layout(push_constant) uniform pushConstant{
// x: mesh, y: prim, z: 0, w: vertex
uvec4 geometryOffsets;
// x: meshFirst, y: meshMax
uvec4 drawRange;
};
layout(std140, binding = SCENE_UBO_VIEW, set = DSET_SCENE) uniform sceneBuffer {
SceneData scene;
};
layout(std430, binding = SCENE_SSBO_STATS, set = DSET_SCENE) buffer statsBuffer {
CullStats stats;
};
layout(std140, binding= 0, set = DSET_OBJECT) uniform objectBuffer {
ObjectData object;
};
layout(std430, binding = GEOMETRY_SSBO_MESHLETDESC, set = DSET_GEOMETRY) buffer meshletDescBuffer {
uvec4 meshletDescs[];
};
layout(std430, binding = GEOMETRY_SSBO_PRIM, set = DSET_GEOMETRY) buffer primIndexBuffer1 {
uint primIndices1[];
};
layout(std430, binding = GEOMETRY_SSBO_PRIM, set = DSET_GEOMETRY) buffer primIndexBuffer2 {
uint8_t primIndices_u8[];
};
layout(binding=GEOMETRY_TEX_VBO, set=DSET_GEOMETRY) uniform samplerBuffer texVbo;
layout(binding=GEOMETRY_TEX_ABO, set=DSET_GEOMETRY) uniform samplerBuffer texAbo;
/////////////////////////////////////////////////
#include "nvmeshlet_utils.glsl"
uint findNthBit(uint value, uint n)
{
// from https://stackoverflow.com/a/45487375
const uint pop2 = (value & 0x55555555u) + ((value >> 1) & 0x55555555u);
const uint pop4 = (pop2 & 0x33333333u) + ((pop2 >> 2) & 0x33333333u);
const uint pop8 = (pop4 & 0x0f0f0f0fu) + ((pop4 >> 4) & 0x0f0f0f0fu);
const uint pop16 = (pop8 & 0x00ff00ffu) + ((pop8 >> 8) & 0x00ff00ffu);
const uint pop32 = (pop16 & 0x000000ffu) + ((pop16 >> 16) & 0x000000ffu);
uint rank = 0;
uint temp;
if (n++ >= pop32)
return 31; // avoid out of bounds, so report 31 even when not found
temp = pop16 & 0xffu;
/* if (n > temp) { n -= temp; rank += 16; } */
rank += ((temp - n) & 256) >> 4;
n -= temp & ((temp - n) >> 8);
temp = (pop8 >> rank) & 0xffu;
/* if (n > temp) { n -= temp; rank += 8; } */
rank += ((temp - n) & 256) >> 5;
n -= temp & ((temp - n) >> 8);
temp = (pop4 >> rank) & 0x0fu;
/* if (n > temp) { n -= temp; rank += 4; } */
rank += ((temp - n) & 256) >> 6;
n -= temp & ((temp - n) >> 8);
temp = (pop2 >> rank) & 0x03u;
/* if (n > temp) { n -= temp; rank += 2; } */
rank += ((temp - n) & 256) >> 7;
n -= temp & ((temp - n) >> 8);
temp = (value >> rank) & 0x01u;
/* if (n > temp) rank += 1; */
rank += ((temp - n) & 256) >> 8;
return rank;
}
uint findNthBit(uint64_t v, uint i)
{
uvec2 v2 = unpackUint2x32(v);
uint s = v2.x;
uint o = 0;
uint bc = bitCount(v2.x);
if (i >= bc) {
i -= bc;
o += 32;
s = v2.y;
}
return findNthBit(s, i) + o;
}
uint myBitCount(uint32_t v)
{
return bitCount(v);
}
uint myBitCount(uint64_t v)
{
uvec2 v2 = unpackUint2x32(v);
return bitCount(v2.x) + bitCount(v2.y);
}
/////////////////////////////////////////////////
// MESH INPUT
#if USE_TASK_STAGE
struct Task {
uint baseID;
uint8_t deltaIDs[NVMESHLET_PER_TASK];
};
taskPayloadSharedEXT Task IN;
// gl_WorkGroupID.x runs from [0 .. parentTask.groupCountX - 1]
uint meshletID = IN.baseID + IN.deltaIDs[gl_WorkGroupID.x];
#else
uint meshletID = gl_WorkGroupID.x + drawRange.x;
#endif
uint laneID = gl_LocalInvocationID.x;
////////////////////////////////////////////////////////////
// INPUT
// If you work from fixed vertex definitions and don't need dynamic
// format conversions by texture formats, or don't mind
// creating multiple shader permutations, you may want to
// use ssbos here, instead of tbos
vec3 getPosition( uint vidx ){
return texelFetch(texVbo, int(vidx)).xyz;
}
vec3 getNormal( uint vidx ){
return texelFetch(texAbo, int(vidx * VERTEX_NORMAL_STRIDE)).xyz;
}
vec4 getExtra( uint vidx, uint xtra ){
return texelFetch(texAbo, int(vidx * VERTEX_NORMAL_STRIDE + 1 + xtra));
}
////////////////////////////////////////////////////////////
// OUTPUT
#if SHOW_PRIMIDS
// nothing to output
#elif USE_BARYCENTRIC_SHADING
layout(location=0) out Interpolants {
flat uint meshletID;
} OUT[];
layout(location=1) out ManualInterpolants {
uint vidx;
} OUTBary[];
#else
layout(location=0) out Interpolants {
vec3 wPos;
vec3 wNormal;
flat uint meshletID;
#if VERTEX_EXTRAS_COUNT
vec4 xtra[VERTEX_EXTRAS_COUNT];
#endif
} OUT[];
#endif
//////////////////////////////////////////////////
// VERTEX/PRIMITIVE CULLING SETUP
// When we do per-primitive culling we have two options
// how to deal with the vertex outputs:
// - do them regardless of culling result (USE_VERTEX_CULL == 0)
// - wait until we know which vertices are actually used (USE_VERTEX_CULL == 1)
// some of this HW defines may be vendor specific preference at the moment
// use gl_CullPrimitiveEXT if applicable otherwise degenerate
// FIXME NVIDIA need to optimize 1 case
#ifndef HW_CULL_PRIMITIVE
#define HW_CULL_PRIMITIVE 1
#endif
// HW_TEMPVERTEX
// defines how much information we store in temp registers
// for the vertices. We need them in temp registers so
// that primitive culling can access all vertices a
// primitive uses via shuffle.
// One big difference to NV code is that EXT does not
// allow read-access to output data
// store screen position, use less temp registers and
// speeds up primitive culling, but may need to
// re-fetch/transform vertex position again.
#define HW_TEMPVERTEX_SPOS 0
// store world position and avoid the later re-fetch
// but during primitive culling need to transform all 3 vertices.
#define HW_TEMPVERTEX_WPOS 1
#if EXT_USE_ANY_COMPACTION
// experiment with what store type is quicker
#define HW_TEMPVERTEX HW_TEMPVERTEX_WPOS
#else
// without compaction
// always use smallest here, as vertex wpos
// is not used later at all
#define HW_TEMPVERTEX HW_TEMPVERTEX_SPOS
#endif
struct TempVertex
{
#if HW_TEMPVERTEX == HW_TEMPVERTEX_SPOS
vec2 sPos;
#elif HW_TEMPVERTEX == HW_TEMPVERTEX_WPOS
vec3 wPos;
#endif
#if USE_VERTEX_CULL || EXT_USE_ANY_COMPACTION
uint vidx;
#endif
};
// as this shader alywas does per-primitive culling
// we need to able to fetch the vertex screen positions
TempVertex tempVertices[MESHLET_VERTEX_ITERATIONS];
#if USE_VERTEX_CULL
#if NVMESHLET_VERTEX_COUNT == 64
#define vertexBits_t uint64_t
#else
#define vertexBits_t uint
#endif
vertexBits_t tempVertexUsed = 0;
// we encode vertex usage in the highest bit of vidx
// assuming it is available
bool vertexcull_isVertexUsed(uint vert)
{
return (tempVertexUsed & (vertexBits_t(1) << vert)) != 0;
}
uint vertexcull_postCompactIndex(uint vert)
{
return uint(myBitCount(tempVertexUsed & ((vertexBits_t(1) << vert)-1)));
}
uint vertexcull_preCompactIndex(uint overt)
{
return findNthBit(tempVertexUsed, overt);
}
void vertexcull_setVertexUsed(uint a) {
// non-atomic write as read/write hazard should not be
// an issue here, this function will always just
// add the topmost bit
tempVertexUsed |= vertexBits_t(1) << a;
}
#endif
#if USE_VERTEX_CULL || EXT_USE_ANY_COMPACTION
uint vertexcull_readVertexIndex(uint vert) {
#if USE_VERTEX_CULL && EXT_COMPACT_VERTEX_OUTPUT && EXT_LOCAL_INVOCATION_VERTEX_OUTPUT
#if EXT_MESH_SUBGROUP_SIZE == NVMESHLET_VERTEX_COUNT
return subgroupShuffle(tempVertices[0].vidx, vert);
#elif EXT_MESH_SUBGROUP_SIZE == 32
uint lo = subgroupShuffle(tempVertices[0].vidx, vert & 31);
uint hi = subgroupShuffle(tempVertices[1].vidx, vert & 31);
return vert < 32 ? lo : hi;
#endif
#else
#if EXT_MESH_SUBGROUP_SIZE == NVMESHLET_VERTEX_COUNT
return tempVertices[0].vidx;
#else
return vert < 32 ? tempVertices[0].vidx : tempVertices[1].vidx;
#endif
#endif
}
#endif
uint tempTopologies[MESHLET_PRIMITIVE_ITERATIONS];
#if NVMESHLET_PRIMITIVE_COUNT == 64
#define primBits_t uint64_t
#else
#define primBits_t uint
#endif
primBits_t tempPrimUsed = 0;
uint primcull_preCompactIndex(uint overt)
{
return findNthBit(tempPrimUsed, overt);
}
uint primcull_getTopology(uint idx)
{
#if EXT_COMPACT_PRIMITIVE_OUTPUT && EXT_LOCAL_INVOCATION_PRIMITIVE_OUTPUT
#if EXT_MESH_SUBGROUP_SIZE == NVMESHLET_PRIMITIVE_COUNT
return subgroupShuffle(tempTopologies[0], idx);
#else
uint lo = subgroupShuffle(tempTopologies[0], idx & 31);
uint hi = subgroupShuffle(tempTopologies[1], idx & 31);
return idx < 32 ? lo : hi;
#endif
#else
#if EXT_MESH_SUBGROUP_SIZE == NVMESHLET_PRIMITIVE_COUNT
return tempTopologies[0];
#else
return idx < 32 ? tempTopologies[0] : tempTopologies[1];
#endif
#endif
}
#if HW_TEMPVERTEX == HW_TEMPVERTEX_SPOS
vec2 primcull_getVertexSPos(uint vert) {
#if EXT_MESH_SUBGROUP_SIZE == NVMESHLET_VERTEX_COUNT
return subgroupShuffle(tempVertices[0].sPos, vert);
#else
vec2 lo = subgroupShuffle(tempVertices[0].sPos, vert & 31);
vec2 hi = subgroupShuffle(tempVertices[1].sPos, vert & 31);
return vert < 32 ? lo : hi;
#endif
}
#elif HW_TEMPVERTEX == HW_TEMPVERTEX_WPOS
vec4 primcull_getVertexHPos(uint vert) {
#if EXT_MESH_SUBGROUP_SIZE == NVMESHLET_VERTEX_COUNT
vec3 wPos = subgroupShuffle(tempVertices[0].wPos, vert);
#else
vec3 lo = subgroupShuffle(tempVertices[0].wPos, vert & 31);
vec3 hi = subgroupShuffle(tempVertices[1].wPos, vert & 31);
vec3 wPos = vert < 32 ? lo : hi;
#endif
return (scene.viewProjMatrix * vec4(wPos,1));
}
#if EXT_USE_ANY_COMPACTION
vec3 primcull_getVertexWPos(uint vert) {
#if USE_VERTEX_CULL && EXT_COMPACT_VERTEX_OUTPUT && EXT_LOCAL_INVOCATION_VERTEX_OUTPUT
#if EXT_MESH_SUBGROUP_SIZE == NVMESHLET_VERTEX_COUNT
vec3 wPos = subgroupShuffle(tempVertices[0].wPos, vert);
#else
vec3 lo = subgroupShuffle(tempVertices[0].wPos, vert & 31);
vec3 hi = subgroupShuffle(tempVertices[1].wPos, vert & 31);
vec3 wPos = vert < 32 ? lo : hi;
#endif
#else
#if EXT_MESH_SUBGROUP_SIZE == NVMESHLET_VERTEX_COUNT
vec3 wPos = tempVertices[0].wPos;
#else
vec3 wPos = vert < 32 ? tempVertices[0].wPos : tempVertices[1].wPos;
#endif
#endif
return wPos;
}
#endif
#else
#error "HW_TEMPVERTEX not supported"
#endif
//////////////////////////////////////////////////
// VERTEX EXECUTION
// This is the code that is normally done in the vertex-shader
// "vidx" is what gl_VertexIndex would be
//
// We split vertex-shading from attribute-shading,
// to highlight the differences between the drawmeshlet_cull.mesh.glsl
// and drawmeshlet_basic.mesh.glsl files (just use a file-diff
// program to view the two)
// the temp vertex is required for per-primitive culling
// as well as vertex culling
void writeTempVertex(uint vert, const uint vidx, vec3 wPos, vec4 hPos)
{
#if HW_TEMPVERTEX == HW_TEMPVERTEX_SPOS
vec2 sPos = getScreenPos(hPos);
#endif
#if EXT_MESH_SUBGROUP_SIZE != NVMESHLET_VERTEX_COUNT
if (vert < 32) {
#endif
#if HW_TEMPVERTEX == HW_TEMPVERTEX_SPOS
tempVertices[0].sPos = sPos;
#elif HW_TEMPVERTEX == HW_TEMPVERTEX_WPOS
tempVertices[0].wPos = wPos;
#else
#error "HW_TEMPVERTEX not supported"
#endif
#if USE_VERTEX_CULL || EXT_USE_ANY_COMPACTION
tempVertices[0].vidx = vidx;
#endif
#if EXT_MESH_SUBGROUP_SIZE != NVMESHLET_VERTEX_COUNT
}
else {
#if HW_TEMPVERTEX == HW_TEMPVERTEX_SPOS
tempVertices[1].sPos = sPos;
#elif HW_TEMPVERTEX == HW_TEMPVERTEX_WPOS
tempVertices[1].wPos = wPos;
#else
#error "HW_TEMPVERTEX not supported"
#endif
#if USE_VERTEX_CULL || EXT_USE_ANY_COMPACTION
tempVertices[1].vidx = vidx;
#endif
}
#endif
}
#if EXT_USE_ANY_COMPACTION
void procTempVertex(uint vert, const uint vidx)
{
vec3 oPos = getPosition(vidx);
vec3 wPos = (object.worldMatrix * vec4(oPos,1)).xyz;
vec4 hPos = (scene.viewProjMatrix * vec4(wPos,1));
writeTempVertex(vert, vidx, wPos, hPos);
}
#endif
void procVertex(uint vert, const uint vidx, vec3 inWPos)
{
#if HW_TEMPVERTEX == HW_TEMPVERTEX_SPOS || !EXT_USE_ANY_COMPACTION
vec3 oPos = getPosition(vidx);
vec3 wPos = (object.worldMatrix * vec4(oPos,1)).xyz;
#elif HW_TEMPVERTEX == HW_TEMPVERTEX_WPOS
vec3 wPos = inWPos;
#else
#error "HW_TEMPVERTEX not supported"
#endif
vec4 hPos = (scene.viewProjMatrix * vec4(wPos,1));
gl_MeshVerticesEXT[vert].gl_Position = hPos;
#if !SHOW_PRIMIDS
#if USE_BARYCENTRIC_SHADING
OUTBary[vert].vidx = vidx;
OUT[vert].meshletID = meshletID;
#else
OUT[vert].wPos = wPos;
OUT[vert].meshletID = meshletID;
#endif
#endif
#if USE_CLIPPING
#if IS_VULKAN
// spir-v annoyance, doesn't unroll the loop and therefore cannot derive the number of clip distances used
#if NUM_CLIPPING_PLANES > 0
gl_MeshVerticesEXT[vert].gl_ClipDistance[0] = dot(scene.wClipPlanes[0], vec4(wPos,1));
#endif
#if NUM_CLIPPING_PLANES > 1
gl_MeshVerticesEXT[vert].gl_ClipDistance[1] = dot(scene.wClipPlanes[1], vec4(wPos,1));
#endif
#if NUM_CLIPPING_PLANES > 2
gl_MeshVerticesEXT[vert].gl_ClipDistance[2] = dot(scene.wClipPlanes[2], vec4(wPos,1));
#endif
#else
for (int i = 0; i < NUM_CLIPPING_PLANES; i++){
gl_MeshVerticesEXT[vert].gl_ClipDistance[i] = dot(scene.wClipPlanes[i], vec4(wPos,1));
}
#endif
#endif
#if !EXT_USE_ANY_COMPACTION
// without any compaction we still need to write temp vertex
// as it's used for primitive culling
writeTempVertex(vert, vidx, wPos, hPos);
#endif
}
void procAttributes(uint vert, const uint vidx)
{
#if !SHOW_PRIMIDS && !USE_BARYCENTRIC_SHADING
vec3 oNormal = getNormal(vidx);
vec3 wNormal = mat3(object.worldMatrixIT) * oNormal;
OUT[vert].wNormal = wNormal;
#if VERTEX_EXTRAS_COUNT
UNROLL_LOOP
for (int i = 0; i < VERTEX_EXTRAS_COUNT; i++) {
vec4 xtra = getExtra(vidx, i);
OUT[vert].xtra[i] = xtra;
}
#endif
#endif
}
//////////////////////////////////////////////////
// MESH EXECUTION
// One can see that the primary mesh-shader code is agnostic of the vertex-shading work.
// In theory it should be possible to even automatically generate mesh-shader SPIR-V
// as combination of a template mesh-shader and a vertex-shader provided as SPIR-V
void main()
{
#if NVMESHLET_ENCODING == NVMESHLET_ENCODING_PACKBASIC
// LOAD HEADER PHASE
uvec4 desc = meshletDescs[meshletID + geometryOffsets.x];
uint vertMax;
uint primMax;
uint vidxStart;
uint vidxBits;
uint vidxDiv;
uint primStart;
uint primDiv;
decodeMeshlet(desc, vertMax, primMax, primStart, primDiv, vidxStart, vidxBits, vidxDiv);
vidxStart += geometryOffsets.y / 4;
primStart += geometryOffsets.y / 4;
uint primCount = primMax + 1;
uint vertCount = vertMax + 1;
#if !EXT_USE_ANY_COMPACTION
// OUTPUT ALLOCATION
// no compaction whatsoever, pre-allocate space early, directly
// fill in crucial data
SetMeshOutputsEXT(vertCount, primCount);
#endif
// VERTEX INITIAL PROCESSING
{
UNROLL_LOOP
for (uint i = 0; i < uint(MESHLET_VERTEX_ITERATIONS); i++)
{
uint vert = laneID + i * WORKGROUP_SIZE;
uint vertLoad = min(vert, vertMax);
{
uint idx = (vertLoad) >> (vidxDiv-1);
uint shift = (vertLoad) & (vidxDiv-1);
uint vidx = primIndices1[idx + vidxStart];
vidx <<= vidxBits * (1-shift);
vidx >>= vidxBits;
vidx += geometryOffsets.w;
{
#if EXT_USE_ANY_COMPACTION
// for compaction we will make final writes
// of vertices after primitive culling and at
// this point only compute enough for primitive
// culling
procTempVertex(vert, vidx);
#else
// process our vertex in full, as we need it for
// culling anyway
procVertex(vert, vidx, vec3(0,0,0));
#if !USE_VERTEX_CULL
// without vertex culling just write
// out all attributes immediately
// otherwise will defer attributes.
procAttributes(vert, vidx);
#endif
#endif
}
}
}
}
// PRIMITIVE TOPOLOGY
{
#if (EXT_USE_ANY_COMPACTION && USE_EARLY_TOPOLOGY_LOAD)
// with compaction we do all loads up-front
uint readBegin = primStart * 4;
UNROLL_LOOP
for (uint i = 0; i < uint(MESHLET_PRIMITIVE_ITERATIONS); i++)
{
uint prim = laneID + i * WORKGROUP_SIZE;
uint primRead = min(prim, primMax);
u8vec4 topology = u8vec4(primIndices_u8[readBegin + primRead * 3 + 0],
primIndices_u8[readBegin + primRead * 3 + 1],
primIndices_u8[readBegin + primRead * 3 + 2],
uint8_t(prim));
tempTopologies[i] = pack32(topology);
}
#endif
}
#else
#error "NVMESHLET_ENCODING not supported"
#endif
////////////////////////////////////////////
// PRIMITIVE CULLING PHASE
barrier();
// for pipelining the index loads it is actually faster to load
// the primitive indices first, and then do the culling loop here,
// rather than combining load / culling. This behavior, however,
// could vary per vendor.
#if !(EXT_USE_ANY_COMPACTION && USE_EARLY_TOPOLOGY_LOAD)
uint readBegin = primStart * 4;
#endif
UNROLL_LOOP
for (uint i = 0; i < uint(MESHLET_PRIMITIVE_ITERATIONS); i++)
{
uint prim = laneID + i * WORKGROUP_SIZE;
bool primVisible = false;
u8vec4 topology;
#if (EXT_USE_ANY_COMPACTION && USE_EARLY_TOPOLOGY_LOAD)
topology = unpack8(tempTopologies[i]);
#else
uint primRead = min(prim, primMax);
topology = u8vec4(primIndices_u8[readBegin + primRead * 3 + 0],
primIndices_u8[readBegin + primRead * 3 + 1],
primIndices_u8[readBegin + primRead * 3 + 2],
uint8_t(prim));
#endif
if (prim > primMax) {
topology = u8vec4(0);
}
// these read via shuffle, cannot be in branch
#if HW_TEMPVERTEX == HW_TEMPVERTEX_SPOS
vec2 as = primcull_getVertexSPos(topology.x);
vec2 bs = primcull_getVertexSPos(topology.y);
vec2 cs = primcull_getVertexSPos(topology.z);
#else
// build triangle
vec4 ah = primcull_getVertexHPos(topology.x);
vec4 bh = primcull_getVertexHPos(topology.y);
vec4 ch = primcull_getVertexHPos(topology.z);
vec2 as = getScreenPos(ah);
vec2 bs = getScreenPos(bh);
vec2 cs = getScreenPos(ch);
#endif
if (prim <= primMax) {
#if USE_MESH_FRUSTUMCULL && HW_TEMPVERTEX != HW_TEMPVERTEX_SPOS && USE_CULLBITS
// if the task-shader is active and does the frustum culling
// then we normally don't execute this here
uint abits = getCullBits(ah);
uint bbits = getCullBits(bh);
uint cbits = getCullBits(ch);
primVisible = testTriangle(as.xy, bs.xy, cs.xy, 1.0, abits, bbits, cbits);
#elif USE_MESH_FRUSTUMCULL
// the simple viewport culling here only does 2D check
primVisible = testTriangle(as.xy, bs.xy, cs.xy, 1.0, true);
#else
// assumes all heavy lifting on frustum culling is done before
// either by task-shader or indirect draws etc. (not used in this sample)
primVisible = testTriangle(as.xy, bs.xy, cs.xy, 1.0, false);
#endif
if (primVisible) {
#if USE_VERTEX_CULL
vertexcull_setVertexUsed(topology.x);
vertexcull_setVertexUsed(topology.y);
vertexcull_setVertexUsed(topology.z);
#endif
}
#if !EXT_USE_ANY_COMPACTION
{
#if HW_CULL_PRIMITIVE
// use gl_CullPrimitiveEXT, write this prior other per-primitive outputs of same primitive
gl_MeshPrimitivesEXT[prim].gl_CullPrimitiveEXT = !primVisible;
gl_PrimitiveTriangleIndicesEXT[prim] = uvec3(topology.x, topology.y, topology.z); // avoid branch always write
#else
// use degenerate triangle indices
gl_PrimitiveTriangleIndicesEXT[prim] = primVisible ? uvec3(topology.x, topology.y, topology.z) : uvec3(0);
#endif
#if SHOW_PRIMIDS
// let's compute some fake unique primitiveID
gl_MeshPrimitivesEXT[prim].gl_PrimitiveID = int((meshletID + geometryOffsets.x) * NVMESHLET_PRIMITIVE_COUNT + uint(topology.w));
#endif
}
#elif (!USE_EARLY_TOPOLOGY_LOAD)
tempTopologies[i] = pack32(topology);
#endif
}
#if EXT_COMPACT_PRIMITIVE_OUTPUT || USE_VERTEX_CULL || USE_STATS
{
uvec4 votePrims = subgroupBallot(primVisible);
#if NVMESHLET_PRIMITIVE_COUNT == 64 && EXT_MESH_SUBGROUP_SIZE == 64
tempPrimUsed = packUint2x32(votePrims.xy);
#elif NVMESHLET_PRIMITIVE_COUNT == 64 && EXT_MESH_SUBGROUP_SIZE == 32
tempPrimUsed |= primBits_t(votePrims.x) << (i*32);
#else
tempPrimUsed = votePrims.x;
#endif
}
#endif
}
tempPrimUsed = subgroupOr(tempPrimUsed);
uint outPrimCount = myBitCount(tempPrimUsed);
#if USE_VERTEX_CULL
////////////////////////////////////////////
// VERTEX COMPACTION PHASE
tempVertexUsed = subgroupOr(tempVertexUsed);
uint outVertCount = myBitCount(tempVertexUsed);
#else
uint outVertCount = vertCount;
#endif
////////////////////////////////////////////
// OUTPUT
barrier();
if (laneID == 0) {
#if USE_STATS
atomicAdd(stats.meshletsOutput, 1);
atomicAdd(stats.trisOutput, outPrimCount);
atomicAdd(stats.attrInput, vertCount);
atomicAdd(stats.attrOutput, outVertCount);
#endif
}
#if EXT_USE_ANY_COMPACTION
#if !EXT_COMPACT_PRIMITIVE_OUTPUT
outPrimCount = primCount;
#endif
#if !EXT_COMPACT_VERTEX_OUTPUT
outVertCount = vertCount;
#endif
SetMeshOutputsEXT(outVertCount, outPrimCount);
UNROLL_LOOP
for (uint i = 0; i < uint(MESHLET_PRIMITIVE_ITERATIONS); i++)
{
#if EXT_COMPACT_PRIMITIVE_OUTPUT && !EXT_LOCAL_INVOCATION_PRIMITIVE_OUTPUT
uint prim = laneID + i * WORKGROUP_SIZE;
u8vec4 topology = unpack8(tempTopologies[i]);
primBits_t primBit = primBits_t(1) << (prim);
if ((tempPrimUsed & primBit) != 0)
{
uint outidx = myBitCount(tempPrimUsed & (primBit-1));
#elif EXT_COMPACT_PRIMITIVE_OUTPUT && EXT_LOCAL_INVOCATION_PRIMITIVE_OUTPUT
uint outidx = laneID + i * WORKGROUP_SIZE;
// must be outside branch when reading via shuffle
uint prim = primcull_preCompactIndex(outidx);
u8vec4 topology = unpack8(primcull_getTopology(prim));
if (outidx < outPrimCount)
{
#else
uint prim = laneID + i * WORKGROUP_SIZE;
u8vec4 topology = unpack8(tempTopologies[i]);
primBits_t primBit = primBits_t(1) << (prim);
if ((tempPrimUsed & primBit) != 0)
{
uint outidx = prim;
#endif
#if EXT_COMPACT_VERTEX_OUTPUT && USE_VERTEX_CULL
uvec3 outTopo = uvec3(vertexcull_postCompactIndex(topology.x), vertexcull_postCompactIndex(topology.y), vertexcull_postCompactIndex(topology.z));
#else
uvec3 outTopo = uvec3(topology.x, topology.y, topology.z);
#endif
gl_PrimitiveTriangleIndicesEXT[outidx] = outTopo;
#if SHOW_PRIMIDS
// let's compute some fake unique primitiveID
gl_MeshPrimitivesEXT[outidx].gl_PrimitiveID = int((meshletID + geometryOffsets.x) * NVMESHLET_PRIMITIVE_COUNT + uint(topology.w));
#endif
}
}
#endif
#if USE_VERTEX_CULL || EXT_USE_ANY_COMPACTION
// OUTPUT VERTICES
UNROLL_LOOP
for (uint i = 0; i < uint(MESHLET_VERTEX_ITERATIONS); i++)
{
#if USE_VERTEX_CULL && EXT_COMPACT_VERTEX_OUTPUT && !EXT_LOCAL_INVOCATION_VERTEX_OUTPUT
uint vert = laneID + i * WORKGROUP_SIZE;
bool used = vert <= vertMax && vertexcull_isVertexUsed( vert );
if (used)
{
uint overt = vertexcull_postCompactIndex(vert);
uint vidx = vertexcull_readVertexIndex(vert);
vec3 wPos = primcull_getVertexWPos(vert);
#elif USE_VERTEX_CULL && EXT_COMPACT_VERTEX_OUTPUT && EXT_LOCAL_INVOCATION_VERTEX_OUTPUT
uint overt = laneID + i * WORKGROUP_SIZE;
// must be outside branch when reading via shuffle
uint vert = vertexcull_preCompactIndex(overt);
uint vidx = vertexcull_readVertexIndex(vert);
vec3 wPos = primcull_getVertexWPos(vert);
if (overt < outVertCount)
{
#else
uint vert = laneID + i * WORKGROUP_SIZE;
#if USE_VERTEX_CULL
bool used = vert <= vertMax && vertexcull_isVertexUsed( vert );
#else
bool used = vert <= vertMax;
#endif
if (used)
{
uint overt = vert;
uint vidx = vertexcull_readVertexIndex( vert );
#if EXT_USE_ANY_COMPACTION
vec3 wPos = primcull_getVertexWPos(vert);
#endif
#endif
#if EXT_USE_ANY_COMPACTION
procVertex(overt, vidx, wPos);
#endif
procAttributes(overt, vidx);
}
}