mirror of https://github.com/minetest/minetest.git
322 lines
8.7 KiB
C++
322 lines
8.7 KiB
C++
#include "CGLTFMeshFileLoader.h"
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#include "CMeshBuffer.h"
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#include "coreutil.h"
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#include "IAnimatedMesh.h"
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#include "IReadFile.h"
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#include "irrTypes.h"
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#include "path.h"
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#include "S3DVertex.h"
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#include "SAnimatedMesh.h"
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#include "SColor.h"
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#include "SMesh.h"
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#include "vector3d.h"
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#define TINYGLTF_IMPLEMENTATION
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#include <tiny_gltf.h>
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#include <cstddef>
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#include <cstring>
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#include <memory>
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#include <string>
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#include <tuple>
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#include <utility>
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#include <vector>
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/* Notes on the coordinate system.
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*
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* glTF uses a right-handed coordinate system where +Z is the
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* front-facing axis, and Irrlicht uses a left-handed coordinate
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* system where -Z is the front-facing axis.
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* We convert between them by reflecting the mesh across the X axis.
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* Doing this correctly requires negating the Z coordinate on
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* vertex positions and normals, and reversing the winding order
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* of the vertex indices.
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*/
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// A helper function to disable tinygltf embedded image loading
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static bool dummyImageLoader(tinygltf::Image *a,
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const int b, std::string *c,
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std::string *d,
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int e,
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int f,
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const unsigned char * g,
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int h,
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void *userPointer)
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{
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return false;
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};
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namespace irr {
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namespace scene {
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CGLTFMeshFileLoader::BufferOffset::BufferOffset(
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const std::vector<unsigned char>& buf,
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const std::size_t offset)
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: m_buf(buf)
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, m_offset(offset)
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{
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}
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CGLTFMeshFileLoader::BufferOffset::BufferOffset(
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const CGLTFMeshFileLoader::BufferOffset& other,
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const std::size_t fromOffset)
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: m_buf(other.m_buf)
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, m_offset(other.m_offset + fromOffset)
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{
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}
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unsigned char CGLTFMeshFileLoader::BufferOffset::at(
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const std::size_t fromOffset) const
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{
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return m_buf.at(m_offset + fromOffset);
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}
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CGLTFMeshFileLoader::CGLTFMeshFileLoader() noexcept
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{
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}
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bool CGLTFMeshFileLoader::isALoadableFileExtension(
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const io::path& filename) const
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{
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return core::hasFileExtension(filename, "gltf");
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}
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IAnimatedMesh* CGLTFMeshFileLoader::createMesh(io::IReadFile* file)
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{
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tinygltf::Model model{};
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if (file->getSize() == 0 || !tryParseGLTF(file, model)) {
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return nullptr;
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}
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// Create the base mesh
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SMesh* mesh { new SMesh {} };
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// Iterate models
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for (std::size_t meshIndex = 0;
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meshIndex < model.meshes.size(); meshIndex++) {
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// Iterate primitives
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for (std::size_t primitiveIndex = 0; primitiveIndex < model
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.meshes[meshIndex].primitives.size(); primitiveIndex++) {
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const auto positionAccessorId = model.meshes[meshIndex]
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.primitives[primitiveIndex].attributes["POSITION"];
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const auto indicesAccessorId = model.meshes[meshIndex]
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.primitives[primitiveIndex].indices;
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// Creates counts for preallocation
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std::size_t vertexCount = model.accessors[positionAccessorId].count;
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// We must count to create containers for the data
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// Create new buffer for vertices, positions, and normals
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auto* vertexBuffer = new video::S3DVertex[vertexCount]();
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// This is used to copy data into the vertexBuffer
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Span<video::S3DVertex> verticesBuffer{vertexBuffer,vertexCount};
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// Create dynamic indices buffer so it's easier to work with.
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// Preallocate needed resources to boost game startup speed
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std::vector<u16> indicesBuffer(model.accessors[
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indicesAccessorId].count);
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ModelParser parser(std::move(model));
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parser.getIndices(indicesAccessorId, indicesBuffer);
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parser.getVertices(positionAccessorId,
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verticesBuffer,
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meshIndex,
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primitiveIndex);
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std::reverse(indicesBuffer.begin(),indicesBuffer.end());
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// Create the mesh buffer
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SMeshBuffer* meshbuf { new SMeshBuffer {} };
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meshbuf->append(vertexBuffer, vertexCount, indicesBuffer.data(),
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indicesBuffer.size());
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mesh->addMeshBuffer(meshbuf);
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}
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}
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// Create the mesh animations
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SAnimatedMesh* animatedMesh { new SAnimatedMesh {} };
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animatedMesh->addMesh(mesh);
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return animatedMesh;
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}
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CGLTFMeshFileLoader::ModelParser::ModelParser(
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const tinygltf::Model& model)
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: m_model(model)
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{
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}
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CGLTFMeshFileLoader::ModelParser::ModelParser(
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const tinygltf::Model&& model)
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: m_model(model)
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{
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}
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void CGLTFMeshFileLoader::ModelParser::getIndices(
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const std::size_t accessorId,
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std::vector<u16>& outIndices) const
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{
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const auto& view = m_model.bufferViews[
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m_model.accessors[accessorId].bufferView];
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const auto& modelIndices = m_model.buffers[view.buffer];
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auto buffOffset = BufferOffset(modelIndices.data, view.byteOffset);
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auto count = m_model.accessors[accessorId].count;
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for (std::size_t i = 0; i < count; i++) {
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outIndices[i] = readPrimitive<u16>(BufferOffset(
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buffOffset, i * sizeof(u16)));
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}
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}
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//Returns a tuple of the current counts (current_vertex_index,
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// current_normals_index, current_tcoords_index)
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void CGLTFMeshFileLoader::ModelParser::getVertices(
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const std::size_t accessorId,
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Span<video::S3DVertex>& outVertices,
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std::size_t meshIndex,
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std::size_t primitiveIndex) const
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{
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copyPositions(outVertices, accessorId);
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const auto normalsField = m_model.meshes[meshIndex]
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.primitives[primitiveIndex].attributes.find("NORMAL");
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if (normalsField != m_model.meshes[meshIndex]
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.primitives[primitiveIndex].attributes.end()) {
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copyNormals(outVertices, normalsField->second);
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}
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const auto tCoordsField = m_model.meshes[meshIndex]
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.primitives[primitiveIndex].attributes.find("TEXCOORD_0");
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if (tCoordsField != m_model.meshes[meshIndex]
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.primitives[primitiveIndex].attributes.end()) {
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copyTCoords(outVertices, tCoordsField->second);
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}
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}
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template <typename T>
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T CGLTFMeshFileLoader::ModelParser::readPrimitive(
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const BufferOffset& readFrom)
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{
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unsigned char d[sizeof(T)]{};
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for (std::size_t i = 0; i < sizeof(T); ++i) {
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d[i] = readFrom.at(i);
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}
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T dest;
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std::memcpy(&dest, d, sizeof(dest));
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return dest;
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}
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core::vector2df CGLTFMeshFileLoader::ModelParser::readVec2DF(
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const CGLTFMeshFileLoader::BufferOffset& readFrom)
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{
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return core::vector2df(readPrimitive<float>(readFrom),
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readPrimitive<float>(BufferOffset(readFrom, sizeof(float))));
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}
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core::vector3df CGLTFMeshFileLoader::ModelParser::readVec3DF(
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const BufferOffset& readFrom,
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const float scale = 1.0f)
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{
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return core::vector3df(
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scale * readPrimitive<float>(readFrom),
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scale * readPrimitive<float>(BufferOffset(readFrom, sizeof(float))),
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-scale * readPrimitive<float>(BufferOffset(readFrom, 2 *
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sizeof(float))));
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}
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void CGLTFMeshFileLoader::ModelParser::copyPositions(
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const Span<video::S3DVertex> vertices,
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const std::size_t accessorId) const
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{
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const auto& view = m_model.bufferViews[
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m_model.accessors[accessorId].bufferView];
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const auto& buffer = m_model.buffers[view.buffer];
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const auto count = m_model.accessors[accessorId].count;
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for (std::size_t i = 0; i < count; i++) {
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const auto v = readVec3DF(BufferOffset(
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buffer.data,
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view.byteOffset + (3 * sizeof(float) * i)),
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getScale());
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vertices.buffer[i].Pos = v;
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}
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}
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void CGLTFMeshFileLoader::ModelParser::copyNormals(
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const Span<video::S3DVertex> vertices,
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const std::size_t accessorId) const
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{
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const auto& view = m_model.bufferViews[
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m_model.accessors[accessorId].bufferView];
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const auto& buffer = m_model.buffers[view.buffer];
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const auto count = m_model.accessors[accessorId].count;
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for (std::size_t i = 0; i < count; i++) {
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const auto n = readVec3DF(BufferOffset( buffer.data,
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view.byteOffset + 3 * sizeof(float) * i ));
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vertices.buffer[i].Normal = n;
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}
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}
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void CGLTFMeshFileLoader::ModelParser::copyTCoords(
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const Span<video::S3DVertex> vertices,
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const std::size_t accessorId) const
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{
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const auto& view = m_model.bufferViews[
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m_model.accessors[accessorId].bufferView];
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const auto& buffer = m_model.buffers[view.buffer];
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const auto count = m_model.accessors[accessorId].count;
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for (std::size_t i = 0; i < count; ++i) {
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const auto t = readVec2DF(BufferOffset(
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buffer.data, view.byteOffset + 2 * sizeof(float) * i));
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vertices.buffer[i].TCoords = t;
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}
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}
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float CGLTFMeshFileLoader::ModelParser::getScale() const
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{
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if (m_model.nodes[0].scale.size() > 0) {
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return static_cast<float>(m_model.nodes[0].scale[0]);
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}
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return 1.0f;
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}
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bool CGLTFMeshFileLoader::tryParseGLTF(io::IReadFile* file,
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tinygltf::Model& model)
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{
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tinygltf::TinyGLTF loader {};
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// Stop embedded textures from making model fail to load
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loader.SetImageLoader(dummyImageLoader, nullptr);
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std::string err {};
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std::string warn {};
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auto buf = std::make_unique<char[]>(file->getSize());
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file->read(buf.get(), file->getSize());
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if (err != "") {
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return false;
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}
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return loader.LoadASCIIFromString(&model, &err, &warn, buf.get(),
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file->getSize(), "", 1);
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}
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} // namespace scene
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} // namespace irr
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