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#include "mesh.h"
static int honey_mesh_lua_draw(lua_State* L)
{
honey_mesh* mesh;
int shader;
honey_lua_parse_arguments(L, 2,
HONEY_USERDATA, &mesh,
HONEY_INTEGER, &shader);
honey_mesh_draw(*mesh, shader);
return 0;
}
static int honey_mesh_lua_delete(lua_State* L)
{
honey_mesh* mesh;
honey_lua_parse_arguments(L, 1, HONEY_USERDATA, &mesh);
honey_mesh_delete(*mesh);
return 0;
}
void honey_setup_mesh(lua_State* L)
{
honey_lua_element mesh_elements[] = {
{ "load", HONEY_FUNCTION, { .function = honey_mesh_load } },
{ "draw", HONEY_FUNCTION, { .function = honey_mesh_lua_draw } },
{ "delete", HONEY_FUNCTION, { .function = honey_mesh_lua_delete } },
};
honey_lua_create_table(L, mesh_elements, 2);
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
static honey_mesh assimp_to_honey_mesh(struct aiMesh* mesh,
struct aiScene* scene)
{
unsigned int vertex_step = 6;
bool mesh_has_uvs = false;
unsigned int n_vertices = mesh->mNumVertices;
if (mesh->mTextureCoords[0]) {
mesh_has_uvs = true;
vertex_step = 8;
}
float* vertices = malloc(sizeof(float) * vertex_step * n_vertices);
for (int i=0; i<n_vertices; i++) {
int j = i*vertex_step;
/* positions */
vertices[j+0] = mesh->mVertices[i].x;
vertices[j+1] = mesh->mVertices[i].y;
vertices[j+2] = mesh->mVertices[i].z;
/* normals */
vertices[j+3] = mesh->mNormals[i].x;
vertices[j+4] = mesh->mNormals[i].y;
vertices[j+5] = mesh->mNormals[i].z;
/* uvs? */
if (mesh_has_uvs) {
vertices[j+6] = mesh->mTextureCoords[0][i].x;
vertices[j+7] = mesh->mTextureCoords[0][i].y;
}
}
unsigned int n_indices = mesh->mNumFaces*3;
unsigned int* indices = malloc(sizeof(unsigned int) * n_indices);
for (int i=0; i<mesh->mNumFaces; i++) {
int j = 3*i;
struct aiFace face = mesh->mFaces[i];
indices[j+0] = face.mIndices[0];
indices[j+1] = face.mIndices[1];
indices[j+2] = face.mIndices[2];
}
honey_mesh result;
if (mesh_has_uvs) {
unsigned int n_attributes = 3;
unsigned int attribute_sizes[] = { 3, 3, 2 };
honey_mesh_new(&result,
vertices, n_vertices,
n_attributes, attribute_sizes,
indices, n_indices);
}
else {
unsigned int n_attributes = 2;
unsigned int attribute_sizes[] = { 3, 3 };
honey_mesh_new(&result,
vertices, n_vertices,
n_attributes, attribute_sizes,
indices, n_indices);
}
free(vertices);
free(indices);
return result;
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
static void process_nodes_recursively(lua_State* L,
struct aiScene* scene,
struct aiNode* node,
int* n_meshes)
{
for (int i=0; i<node->mNumMeshes; i++) {
honey_mesh* mesh = lua_newuserdata(L, sizeof(honey_mesh));
struct aiMesh* assimp_mesh = scene->mMeshes[node->mMeshes[i]];
*mesh = assimp_to_honey_mesh(assimp_mesh, scene);
lua_rawseti(L, -2, *n_meshes);
(*n_meshes)++;
}
for (int i=0; i<node->mNumChildren; i++) {
process_nodes_recursively(L, scene, node->mChildren[i], n_meshes);
}
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
int honey_mesh_load(lua_State* L)
{
char* filename;
honey_lua_parse_arguments(L, 1, HONEY_STRING, &filename);
int n_meshes = 1;
struct aiScene* scene = aiImportFile(filename,
aiProcess_Triangulate |
aiProcess_FlipUVs);
if (scene == NULL) {
char* error;
honey_format_string(&error, "could not open file '%s'", filename);
lua_pushstring(L, error);
free(error);
lua_error(L);
}
if (scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE ||
scene->mRootNode == NULL) {
char* error;
honey_format_string(&error, "could not read mesh(es) in '%s'", filename);
lua_pushstring(L, error);
free(error);
lua_error(L);
}
lua_createtable(L, 0, 0);
process_nodes_recursively(L, scene, scene->mRootNode, &n_meshes);
return 1;
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
honey_result honey_mesh_new(honey_mesh* mesh,
float* vertices,
unsigned int n_vertices,
unsigned int n_attributes,
unsigned int* attribute_sizes,
unsigned int* indices,
unsigned int n_indices) {
if (vertices == NULL || n_vertices == 0) {
return HONEY_MESH_BAD_VERTEX_DATA;
}
if (indices == NULL || n_indices == 0) {
return HONEY_MESH_BAD_INDEX_DATA;
}
unsigned int vertex_size = 0;
for (int i=0; i<n_attributes; i++) {
vertex_size += attribute_sizes[i];
}
(*mesh).n_vertices = n_vertices;
(*mesh).n_indices = n_indices;
glGenVertexArrays(1, &((*mesh).vertex_array));
glGenBuffers(1, &((*mesh).vertex_buffer));
glGenBuffers(1, &((*mesh).element_buffer));
glBindVertexArray((*mesh).vertex_array);
glBindBuffer(GL_ARRAY_BUFFER, (*mesh).vertex_buffer);
glBufferData(GL_ARRAY_BUFFER,
vertex_size * n_vertices * sizeof(float),
vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, (*mesh).element_buffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER,
n_indices * sizeof(unsigned int),
indices, GL_STATIC_DRAW);
/* set up vertex attributes */
unsigned int offset = 0;
for (int i=0; i<n_attributes; i++) {
glEnableVertexAttribArray(i);
glVertexAttribPointer(i,
attribute_sizes[i],
GL_FLOAT,
GL_FALSE,
vertex_size*sizeof(float),
(void*) (offset*sizeof(float)));
offset += attribute_sizes[i];
}
glBindVertexArray(0);
return HONEY_OK;
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
void honey_mesh_draw(honey_mesh mesh, int shader) {
glUseProgram(shader);
glBindVertexArray(mesh.vertex_array);
glDrawElements(GL_TRIANGLES, mesh.n_indices, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
}
/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
void honey_mesh_delete(honey_mesh mesh) {
glDeleteVertexArrays(1, &(mesh.vertex_array));
glDeleteBuffers(1, &(mesh.vertex_buffer));
glDeleteBuffers(1, &(mesh.element_buffer));
}
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