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Integrate MikkTSpace calculation for tangents

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This commit is contained in:
Kim Kulling
2025-07-17 15:46:54 +02:00
parent a5a9f1ba33
commit 5081d263db
6 changed files with 108 additions and 10 deletions
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89
code/PostProcessing/GenerateMikkTSpaceTangents.cpp
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@@ -1,13 +1,100 @@
#include "GenerateMikkTSpaceTangents.h"
#include <assimp/scene.h>
#include <assimp/postprocess.h>
namespace Assimp {
bool GenerateMikkTSpaceTangents::IsActive(unsigned int pFlags) const {
static int get_vertex_index(const SMikkTSpaceContext *context, int iFace, int iVert);
static int get_num_faces(const SMikkTSpaceContext *context);
static int get_num_vertices_of_face(const SMikkTSpaceContext *context, int iFace);
static void get_position(const SMikkTSpaceContext *context, float outpos[], int iFace, int iVert);
static void get_normal(const SMikkTSpaceContext *context, float outnormal[], int iFace, int iVert);
static void get_tex_coords(const SMikkTSpaceContext *context, float outuv[], int iFace, int iVert);
static void set_tspace_basic(const SMikkTSpaceContext *context, const float tangentu[], float fSign, int iFace, int iVert);
static int get_num_faces(const SMikkTSpaceContext *context) {
aiMesh *currentMesh = static_cast<aiMesh*>(context->m_pUserData);
const int numFaces = static_cast<int>(currentMesh->mNumFaces);
return numFaces;
}
static int get_num_vertices_of_face(const SMikkTSpaceContext *context, int iFace) {
aiMesh *currentMesh = static_cast<aiMesh*>(context->m_pUserData);
const aiFace &face = currentMesh->mFaces[iFace];
return face.mNumIndices;
}
static void get_position(const SMikkTSpaceContext *context, float outpos[], int iFace, int iVert) {
aiMesh *currentMesh = static_cast<aiMesh*>(context->m_pUserData);
const aiVector3D &v = currentMesh->mVertices[static_cast<size_t>(iVert)];
outpos[0] = v.x;
outpos[1] = v.y;
outpos[2] = v.z;
}
static void get_normal(const SMikkTSpaceContext *context, float outnormal[], int iFace, int iVert) {
aiMesh *currentMesh = static_cast<aiMesh*>(context->m_pUserData);
const aiVector3D &n = currentMesh->mNormals[static_cast<size_t>(iVert)];
outnormal[0] = n.x;
outnormal[0] = n.y;
outnormal[0] = n.z;
}
static void get_tex_coords(const SMikkTSpaceContext *context, float outuv[], int iFace, int iVert) {
aiMesh *currentMesh = static_cast<aiMesh*>(context->m_pUserData);
aiVector3D &t = currentMesh->mTextureCoords[static_cast<size_t>(iVert)][0];
if (currentMesh->mNumUVComponents[iVert] == 2) {
outuv[0] = t.x;
outuv[1] = t.y;
} else if (currentMesh->mNumUVComponents[iVert] == 3){
outuv[0] = t.x;
outuv[1] = t.y;
outuv[2] = t.z;
}
}
static void set_tspace_basic(const SMikkTSpaceContext *context, const float tangentu[], float fSign, int iFace, int iVert) {
aiMesh *currentMesh = static_cast<aiMesh*>(context->m_pUserData);
currentMesh->mTangents[iVert].x = tangentu[0];
currentMesh->mTangents[iVert].y = tangentu[1];
currentMesh->mTangents[iVert].z = tangentu[1];
}
bool GenerateMikkTSpaceTangents::IsActive(unsigned int pFlags) const {
const bool active = ((pFlags & aiProcess_CalcTangentSpace) != 0);
if (mActive) {
return active;
}
return false;
}
void GenerateMikkTSpaceTangents::Execute(aiScene* pScene) {
mIface.m_getNumFaces = get_num_faces;
mIface.m_getNumVerticesOfFace = get_num_vertices_of_face;
mIface.m_getNormal = get_normal;
mIface.m_getPosition = get_position;
mIface.m_getTexCoord = get_tex_coords;
mIface.m_setTSpaceBasic = set_tspace_basic;
mContext.m_pInterface = &mIface;
for (size_t i=0; i<pScene->mNumMeshes; ++i) {
aiMesh *mesh = pScene->mMeshes[i];
ExecutePerMesh(mesh);
}
}
void GenerateMikkTSpaceTangents::SetupProperties(const Importer *pImp) {
mActive = pImp->GetPropertyBool(AI_CONFIG_POSTPROCESS_USE_MIKKTSPACE_TANGENTS, false);
}
void GenerateMikkTSpaceTangents::ExecutePerMesh(aiMesh *mesh) {
if (mesh == nullptr) {
return;
}
mContext.m_pUserData = mesh;
genTangSpaceDefault(&mContext);
}
} // namespace Assimp