1 files changed, 124 insertions, 0 deletions
diff --git a/mons_3d/src/mesh.c b/mons_3d/src/mesh.c
new file mode 100644
index 0000000..213a24c
--- /dev/null
+++ b/mons_3d/src/mesh.c
@@ -0,0 +1,124 @@
+#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);
+}
+