hair particle velocity buffer fix at fadeout range

README.md

@@ -257,6 +257,7 @@ You can specify command line arguments (without any prefix) to switch between re
 ### Other software using Wicked Engine
 - <a href="https://www.game-guru.com/max">Game Guru MAX</a>: Easy to use game creator software
 - <a href="https://www.youtube.com/watch?v=0SxXmnSQ6Q4">Flytrap</a>: Demoscene production by qop
+- <a href="https://youtu.be/mbmNU5QVM8A?si=9sDMS1LrMsz03f5r">doddering</a>: Demoscene production by qop
 - Your project: add your project to this readme and open a pull request
 
 <br/>

WickedEngine/shaders/hairparticle_simulateCS.hlsl

@@ -18,6 +18,7 @@ RWBuffer<float4> vertexBuffer_POS : register(u1);
 RWBuffer<float4> vertexBuffer_UVS : register(u2);
 RWBuffer<uint> culledIndexBuffer : register(u3);
 RWStructuredBuffer<IndirectDrawArgsIndexedInstanced> indirectBuffer : register(u4);
+RWStructuredBuffer<float3> vertexBuffer_POS_RT : register(u5);
 
 [numthreads(THREADCOUNT_SIMULATEHAIR, 1, 1)]
 void main(uint3 DTid : SV_DispatchThreadID, uint3 Gid : SV_GroupID, uint groupIndex : SV_GroupIndex)
@@ -268,13 +269,15 @@ void main(uint3 DTid : SV_DispatchThreadID, uint3 Gid : SV_GroupID, uint groupIn
 			const float3 wind = sample_wind(rootposition, segmentID + patchPos.y);
 
 			float3 position = rootposition + patchPos + wind;
-			if (distance_culled)
-			{
-				position = 0;
-			}
 
 			vertexBuffer_POS[v0 + vertexID] = float4(position, asfloat(pack_unitvector(normalize(normal + wind))));
 			vertexBuffer_UVS[v0 + vertexID] = uv.xyxy; // a second uv set could be used here
+
+			if (distance_culled)
+			{
+				position = 0; // We can only zero out for raytracing geometry to keep correct prevpos swapping motion vectors!
+			}
+			vertexBuffer_POS_RT[v0 + vertexID] = position;
 		}
 
 		// Frustum culling:

WickedEngine/wiHairParticle.cpp

@@ -105,14 +105,16 @@ namespace wi
 			vb_uvs.size = sizeof(MeshComponent::Vertex_UVS) * 4 * particleCount;
 			ib_culled.size = GetFormatStride(ib_format) * 6 * particleCount;
 			indirect_view.size = sizeof(IndirectDrawArgsIndexedInstanced);
+			vb_pos_raytracing.size = sizeof(float3) * 4 * particleCount;
 
 			bd.size =
 				AlignTo(AlignTo(indirect_view.size, alignment), sizeof(IndirectDrawArgsIndexedInstanced)) + // additional structured buffer alignment
 				AlignTo(AlignTo(simulation_view.size, alignment), sizeof(PatchSimulationData)) + // additional structured buffer alignment
 				AlignTo(vb_pos[0].size, alignment) +
 				AlignTo(vb_pos[1].size, alignment) +
 				AlignTo(vb_uvs.size, alignment) +
-				AlignTo(ib_culled.size, alignment)
+				AlignTo(ib_culled.size, alignment) +
+				AlignTo(AlignTo(vb_pos_raytracing.size, alignment), sizeof(float3))
 			;
 			device->CreateBuffer(&bd, nullptr, &generalBuffer);
 			device->SetName(&generalBuffer, "HairParticleSystem::generalBuffer");
@@ -172,6 +174,14 @@ namespace wi
 			ib_culled.descriptor_uav = device->GetDescriptorIndex(&generalBuffer, SubresourceType::UAV, ib_culled.subresource_uav);
 			buffer_offset += ib_culled.size;
 
+			constexpr uint32_t vb_pos_raytracing_stride = sizeof(float3);
+			buffer_offset = AlignTo(buffer_offset, alignment);
+			buffer_offset = AlignTo(buffer_offset, sizeof(float3));
+			vb_pos_raytracing.offset = buffer_offset;
+			vb_pos_raytracing.subresource_uav = device->CreateSubresource(&generalBuffer, SubresourceType::UAV, vb_pos_raytracing.offset, vb_pos_raytracing.size, nullptr, &vb_pos_raytracing_stride);
+			vb_pos_raytracing.descriptor_uav = device->GetDescriptorIndex(&generalBuffer, SubresourceType::UAV, vb_pos_raytracing.subresource_uav);
+			buffer_offset += vb_pos_raytracing.size;
+
 			primitiveBuffer = wi::renderer::GetIndexBufferForQuads(particleCount);
 		}
 
@@ -232,10 +242,10 @@ namespace wi
 			geometry.triangles.index_format = GetIndexBufferFormat(primitiveBuffer.desc.format);
 			geometry.triangles.index_count = GetParticleCount() * 6;
 			geometry.triangles.index_offset = 0;
-			geometry.triangles.vertex_count = (uint32_t)(vb_pos[0].size / sizeof(MeshComponent::Vertex_POS));
+			geometry.triangles.vertex_count = (uint32_t)(vb_pos_raytracing.size / sizeof(float3));
 			geometry.triangles.vertex_format = Format::R32G32B32_FLOAT;
-			geometry.triangles.vertex_stride = sizeof(MeshComponent::Vertex_POS);
-			geometry.triangles.vertex_byte_offset = vb_pos[0].offset;
+			geometry.triangles.vertex_stride = sizeof(float3);
+			geometry.triangles.vertex_byte_offset = vb_pos_raytracing.offset;
 
 			bool success = device->CreateRaytracingAccelerationStructure(&desc, &BLAS);
 			assert(success);
@@ -272,11 +282,6 @@ namespace wi
 		}
 
 		std::swap(vb_pos[0], vb_pos[1]);
-
-		if (BLAS.IsValid() && !BLAS.desc.bottom_level.geometries.empty())
-		{
-			BLAS.desc.bottom_level.geometries.back().triangles.vertex_byte_offset = vb_pos[0].offset;
-		}
 	}
 	void HairParticleSystem::UpdateGPU(
 		const UpdateGPUItem* items,
@@ -371,6 +376,7 @@ namespace wi
 			device->BindUAV(&hair.generalBuffer, 2, cmd, hair.vb_uvs.subresource_uav);
 			device->BindUAV(&hair.generalBuffer, 3, cmd, hair.ib_culled.subresource_uav);
 			device->BindUAV(&hair.generalBuffer, 4, cmd, hair.indirect_view.subresource_uav);
+			device->BindUAV(&hair.generalBuffer, 5, cmd, hair.vb_pos_raytracing.subresource_uav);
 
 			if (hair.indexBuffer.IsValid())
 			{

WickedEngine/wiHairParticle.h

@@ -23,6 +23,7 @@ namespace wi
 		wi::graphics::GPUBuffer generalBuffer;
 		wi::scene::MeshComponent::BufferView simulation_view;
 		wi::scene::MeshComponent::BufferView vb_pos[2];
+		wi::scene::MeshComponent::BufferView vb_pos_raytracing;
 		wi::scene::MeshComponent::BufferView vb_uvs;
 		wi::scene::MeshComponent::BufferView ib_culled;
 		wi::scene::MeshComponent::BufferView indirect_view;

WickedEngine/wiVersion.cpp

@@ -9,7 +9,7 @@ namespace wi::version
 	// minor features, major updates, breaking compatibility changes
 	const int minor = 71;
 	// minor bug fixes, alterations, refactors, updates
-	const int revision = 339;
+	const int revision = 340;
 
 	const std::string version_string = std::to_string(major) + "." + std::to_string(minor) + "." + std::to_string(revision);