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#include "mesh.h"
#include "vertex.h"
#include "mikktspace.h"
#include <glad/gl.h>
#include <stdlib.h>
void compute_tangents(mons_vertex *vertex_array, int vertex_count, int *index_array, int index_count);
mons_mesh mons_create_mesh(mons_vertex *vertex_array, int vertex_count, int *index_array, int index_count) {
compute_tangents(vertex_array, vertex_count, index_array, index_count);
// VAO & VBO
unsigned int vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
unsigned int vbo;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(mons_vertex) * vertex_count, vertex_array, GL_STATIC_DRAW);
unsigned int ebo;
glGenBuffers(1, &ebo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * index_count, index_array, GL_STATIC_DRAW);
// Set up vertex attributes
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(mons_vertex), 0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(mons_vertex), (void*)(sizeof(mons_vec3)));
glEnableVertexAttribArray(1);
glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, sizeof(mons_vertex), (void*)(sizeof(mons_vec3) * 2));
glEnableVertexAttribArray(2);
glVertexAttribPointer(3, 2, GL_FLOAT, GL_FALSE, sizeof(mons_vertex), (void*)(sizeof(mons_vec3) * 2 + sizeof(mons_vec4)));
glEnableVertexAttribArray(3);
return (mons_mesh) {
.vao = vao,
.element_count = index_count,
};
}
struct mesh_data {
mons_vertex *vertex_array;
int vertex_count;
int *index_array;
int index_count;
};
int get_vertex_index(const SMikkTSpaceContext *context, int i_face, int i_vert) {
struct mesh_data *mesh_data = context->m_pUserData;
int index_index = (i_face * 3) + i_vert;
int index = mesh_data->index_array[index_index];
return index;
}
int get_num_faces(const SMikkTSpaceContext *context) {
struct mesh_data *mesh_data = context->m_pUserData;
return mesh_data->index_count / 3;
}
int get_num_vertices_of_face(const SMikkTSpaceContext *context, int i_face) {
return 3;
}
void get_position(const SMikkTSpaceContext *context, float *outpos, int i_face, int i_vert) {
struct mesh_data *mesh_data = context->m_pUserData;
int index = get_vertex_index(context, i_face, i_vert);
mons_vertex vertex = mesh_data->vertex_array[index];
outpos[0] = vertex.position.x;
outpos[1] = vertex.position.y;
outpos[2] = vertex.position.z;
}
void get_normal(const SMikkTSpaceContext *context, float *outnormal, int i_face, int i_vert) {
struct mesh_data *mesh_data = context->m_pUserData;
int index = get_vertex_index(context, i_face, i_vert);
mons_vertex vertex = mesh_data->vertex_array[index];
outnormal[0] = vertex.normal.x;
outnormal[1] = vertex.normal.y;
outnormal[2] = vertex.normal.z;
}
void get_tex_coords(const SMikkTSpaceContext *context, float *outuv, int i_face, int i_vert) {
struct mesh_data *mesh_data = context->m_pUserData;
int index = get_vertex_index(context, i_face, i_vert);
mons_vertex vertex = mesh_data->vertex_array[index];
outuv[0] = vertex.texture_coords.x;
outuv[1] = vertex.texture_coords.y;
}
void set_tspace_basic(const SMikkTSpaceContext *context, const float *tangentu, float f_sign, int i_face, int i_vert) {
struct mesh_data *mesh_data = context->m_pUserData;
int index = get_vertex_index(context, i_face, i_vert);
mons_vertex *vertex = &mesh_data->vertex_array[index];
vertex->tangent.x = tangentu[0];
vertex->tangent.y = tangentu[1];
vertex->tangent.z = tangentu[2];
vertex->tangent.w = f_sign;
}
void compute_tangents(mons_vertex *vertex_array, int vertex_count, int *index_array, int index_count) {
static SMikkTSpaceInterface iface = {
.m_getNumFaces = get_num_faces,
.m_getNumVerticesOfFace = get_num_vertices_of_face,
.m_getNormal = get_normal,
.m_getPosition = get_position,
.m_getTexCoord = get_tex_coords,
.m_setTSpaceBasic = set_tspace_basic,
};
struct mesh_data mesh_data = {
vertex_array,
vertex_count,
index_array,
index_count,
};
SMikkTSpaceContext context = {
.m_pInterface = &iface,
.m_pUserData = &mesh_data,
};
genTangSpaceDefault(&context);
}
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