FetchContent_Declare(
mikktspace
GIT_REPOSITORY https://github.com/mmikk/MikkTSpace/
GIT_TAG master
GIT_SHALLOW TRUE
GIT_PROGRESS TRUE
)
FetchContent_GetProperties(mikktspace)
if(NOT mikktspace_POPULATED)
FetchContent_MakeAvailable(mikktspace)
message("Fetching mikktspace")
add_library(mikktspace
${mikktspace_SOURCE_DIR}/mikktspace.c
)
target_include_directories(mikktspace
PUBLIC ${mikktspace_SOURCE_DIR}
)
endif()#include <mikktspace.h>
auto CalculateTangents(TAssetMeshData& assetMeshData) -> void {
auto getNumFaces = [](const SMikkTSpaceContext* context) -> int32_t {
auto* meshData = static_cast<TAssetMeshData*>(context->m_pUserData);
return meshData->Indices.size() / 3;
};
auto getNumVerticesOfFace = [](
const SMikkTSpaceContext* context,
const int32_t iFace) -> int32_t {
return 3;
};
auto getPosition = [](
const SMikkTSpaceContext* context,
float posOut[],
const int32_t faceIndex,
const int32_t vertIndex) -> void {
auto* meshData = static_cast<TAssetMeshData*>(context->m_pUserData);
auto index = meshData->Indices[faceIndex * 3 + vertIndex];
const glm::vec3& pos = meshData->Positions[index];
posOut[0] = pos.x;
posOut[1] = pos.y;
posOut[2] = pos.z;
};
auto getNormal = [](
const SMikkTSpaceContext* context,
float normOut[],
const int32_t faceIndex,
const int32_t vertIndex) -> void {
auto* meshData = static_cast<TAssetMeshData*>(context->m_pUserData);
auto index = meshData->Indices[faceIndex * 3 + vertIndex];
const glm::vec3& normal = meshData->Normals[index];
normOut[0] = normal.x;
normOut[1] = normal.y;
normOut[2] = normal.z;
};
auto getUv = [](
const SMikkTSpaceContext* context,
float uvOut[],
const int32_t faceIndex,
const int32_t vertIndex) -> void {
auto* meshData = static_cast<TAssetMeshData*>(context->m_pUserData);
auto index = meshData->Indices[faceIndex * 3 + vertIndex];
const glm::vec2& uv = meshData->Uvs[index];
uvOut[0] = uv.x;
uvOut[1] = uv.y;
};
auto setTSpaceBasic = [](
const SMikkTSpaceContext* context,
const float tangent[],
const float sign,
const int32_t faceIndex,
const int32_t vertIndex) {
auto* meshData = static_cast<TAssetMeshData*>(context->m_pUserData);
auto index = meshData->Indices[faceIndex * 3 + vertIndex];
glm::vec3 t(tangent[0], tangent[1], tangent[2]);
meshData->Tangents[index] = glm::vec4(glm::normalize(t), sign);
};
SMikkTSpaceInterface interface = {
.m_getNumFaces = getNumFaces,
.m_getNumVerticesOfFace = getNumVerticesOfFace,
.m_getPosition = getPosition,
.m_getNormal = getNormal,
.m_getTexCoord = getUv,
.m_setTSpaceBasic = setTSpaceBasic,
};
SMikkTSpaceContext context = {
.m_pInterface = &interface,
.m_pUserData = &assetMeshData
};
genTangSpaceDefault(&context);
}