Files
LNXSDK/lib/haxejolt/JoltPhysics/Jolt/Shaders/HairApplyDeltaTransform.hlsl
2026-03-04 00:50:15 -08:00

43 lines
1.6 KiB
HLSL

// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2026 Jorrit Rouwe
// SPDX-License-Identifier: MIT
#include "HairApplyDeltaTransformBindings.h"
#include "HairCommon.h"
JPH_SHADER_FUNCTION_BEGIN(void, main, cHairPerVertexBatch, 1, 1)
JPH_SHADER_PARAM_THREAD_ID(tid)
JPH_SHADER_FUNCTION_END
{
// Check if this is a valid vertex
uint vtx = tid.x + cNumStrands; // Skip the root of each strand, it's fixed
if (vtx >= cNumVertices)
return;
if (IsVertexFixed(gVerticesFixed, vtx))
return;
// Load the material
uint strand_idx = vtx % cNumStrands;
JPH_HairMaterial material = gMaterials[GetStrandMaterialIndex(gStrandMaterialIndex, strand_idx)];
// Load the vertex
float strand_fraction = GetVertexStrandFraction(gStrandFractions, vtx);
JPH_HairPosition pos = gPositions[vtx];
JPH_HairVelocity vel = gVelocities[vtx];
// Transform the position so that it stays in the same place in world space (if influence is 1)
float influence = GradientSamplerSample(material.mWorldTransformInfluence, strand_fraction);
pos.mPosition += influence * (JPH_Mat44Mul3x4Vec3(cDeltaTransform, pos.mPosition) - pos.mPosition);
// Linear interpolate the rotation based on the influence
pos.mRotation = normalize(JPH_QuatMulQuat(influence * cDeltaTransformQuat + float4(0, 0, 0, 1.0f - influence), pos.mRotation));
// Transform velocities
vel.mVelocity = JPH_Mat44Mul3x3Vec3(cDeltaTransform, vel.mVelocity);
vel.mAngularVelocity = JPH_Mat44Mul3x3Vec3(cDeltaTransform, vel.mAngularVelocity);
// Write back vertex
gPositions[vtx] = pos;
gVelocities[vtx] = vel;
}