hexgame/src/mesh.cpp

#include <cassert>
#include <cstdlib> // calloc

#include <assimp/cimport.h>
#include <assimp/scene.h>
#include <assimp/postprocess.h>

#include <glm/glm.hpp>
#include <glm/geometric.hpp>
#include <glm/gtc/matrix_transform.hpp>

#include "aixlog.hpp"

#include "mesh.h"


bool
meInitAssimp()
{
	LOG(INFO) << "Initializing Assimp\n";
	/* get a handle to the predefined STDOUT log stream and attach
	 * it to the logging system. It remains active for all further
	 * calls to aiImportFile(Ex) and aiApplyPostProcessing. */
	aiLogStream stream = aiGetPredefinedLogStream(aiDefaultLogStream_STDOUT,NULL);
	aiAttachLogStream(&stream);

	return true;
}

meMeshInfo*
meLoadFromFile(const char* filename)
{
	const aiScene* scene = aiImportFile(filename, aiProcessPreset_TargetRealtime_MaxQuality);

	if (scene->mNumMeshes != 1) {
		LOG(ERROR) << "We Can only handle 1 mesh per entity atm\n";
		return nullptr;
	}

	meMeshInfo* mesh = (meMeshInfo*) std::calloc(1, sizeof(meMeshInfo));
	// TODO: using hard model transform for now
	mesh->model_transform = glm::scale(glm::mat4(1), glm::vec3(100, 100, 100));

	// allocate buffers for vertex and index data from mesh
	mesh->num_vertices = scene->mMeshes[0]->mNumVertices;
	mesh->vertices = (glm::vec3 *) std::calloc(mesh->num_vertices, sizeof(glm::vec3));
	mesh->num_indices = scene->mMeshes[0]->mNumFaces * 3; // NOTE: assume 3 vertices per face
	mesh->indices = (uint *) std::calloc(mesh->num_indices, sizeof(uint));

	// copy vertices
	for (uint i = 0; i < mesh->num_vertices; i++) {
		aiVector3D v_in = scene->mMeshes[0]->mVertices[i];
		glm::vec3& v_out = mesh->vertices[i];
		v_out.x = v_in.x;
		v_out.y = v_in.y;
		v_out.z = v_in.z;
	}

	// copy indices
	for (uint i = 0; i < scene->mMeshes[0]->mNumFaces; i++)
		for (uint j = 0; j < 3; j++)
			mesh->indices[i * 3 + j] = scene->mMeshes[0]->mFaces[i].mIndices[j];

#if 1
	// material
	aiMaterial* mat = scene->mMaterials[0];
	aiColor3D color(0.f, 0.f, 0.f);
	if (AI_SUCCESS != mat->Get(AI_MATKEY_COLOR_DIFFUSE, color)) {
		LOG(ERROR) << "Some Assimp-type-error\n";
	} else {
		mesh->diffuse_color.r = color.r;
		mesh->diffuse_color.g = color.g;
		mesh->diffuse_color.b = color.b;
	}
#endif

	// free memeory from assimp
	aiReleaseImport(scene);
	return mesh;
}

void
meFreeMesh(meMeshInfo* mesh)
{
	std::free(mesh->vertices);
	mesh->vertices = nullptr;
	std::free(mesh->indices);
	mesh->indices = nullptr;
	std::free(mesh);
	mesh = nullptr;
}

void
meShutdownAssimp()
{
	aiDetachAllLogStreams();
}