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tinyrenderer/src/obj.c

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#include "obj.h"
#include "aliases.h"
#include "img.h"
#include "mem_arena.h"
#include "pam.h"
#include "typed_list.h"
#include "utils.h"
#include "vec.h"
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define TRIANGLE_VERTICES 3
typedef struct triangle_bbox TriangleBBox;
struct triangle_bbox {
u64 x0;
u64 y0;
u64 x1;
u64 y1;
};
internal void render_triangle(const Triangle *triangle, const Model *model,
const Shader *shader, Render *render,
RenderType render_type, Colour colour);
internal void fill_triangle(Render *render, V3f vertices[TRIANGLE_VERTICES],
V3f normals[TRIANGLE_VERTICES],
V2f coordinates[TRIANGLE_VERTICES], Colour colour,
Image *texture, RenderType type);
internal TriangleBBox get_triangle_bbox(const Image *img,
V3f vertices[TRIANGLE_VERTICES]);
internal V3f get_barycentric_coords(f32 d00, f32 d01, f32 d11, f32 denom,
const V2i *ab, const V2i *ac,
const V2i *ap);
internal V3f get_viewport_vertex(const V3f *vertex, const Image *img);
V3f g_light_dir = {0.0f, 0.0f, 1.0f};
Model load_obj_file(Arena *arena, const char *filename, const char *texture) {
if (!arena) {
return INVALID_MODEL;
}
FILE *fp = fopen(filename, "r");
if (!fp) {
return INVALID_MODEL;
}
Model model = (Model){
.vertices = list_create(V3f, arena),
.normals = list_create(V3f, arena),
.texture_coordinates = list_create(V2f, arena),
.triangles = list_create(Triangle, arena),
};
if (!(model.vertices) || !(model.normals) || !(model.texture_coordinates) ||
!(model.triangles)) {
return INVALID_MODEL;
}
char line[8192];
char identifier[8];
V3f vertex;
V3f normal;
V2f coord;
Triangle triangle;
f32 vx, vy, vz;
f32 nx, ny, nz;
f32 u, v;
u64 fp0, fp1, fp2;
u64 vn0, vn1, vn2;
u64 tx0, tx1, tx2;
while (fgets(line, 8191, fp) != NULL) {
sscanf(line, "%s", identifier);
if (strncmp(identifier, "v", 8) == 0) {
sscanf(line + 2, "%f %f %f", &vx, &vy, &vz);
vertex.x = vx;
vertex.y = vy;
vertex.z = vz;
list_append(V3f, arena, model.vertices, vertex);
} else if (strncmp(identifier, "vn", 8) == 0) {
sscanf(line + 2, "%f %f %f", &nx, &ny, &nz);
normal.x = nx;
normal.y = ny;
normal.z = nz;
list_append(V3f, arena, model.normals, normal);
} else if (strncmp(identifier, "vt", 8) == 0) {
sscanf(line + 2, "%f %f", &u, &v);
coord.u = u;
coord.v = v;
list_append(V2f, arena, model.texture_coordinates, coord);
} else if (strncmp(identifier, "f", 8) == 0) {
sscanf(line + 2, "%lu/%lu/%lu %lu/%lu/%lu %lu/%lu/%lu", &fp0, &tx0, &vn0,
&fp1, &tx1, &vn1, &fp2, &tx2, &vn2);
// OBJ indices start from 1
triangle.p0 = fp0 - 1;
triangle.p1 = fp1 - 1;
triangle.p2 = fp2 - 1;
triangle.n0 = vn0 - 1;
triangle.n1 = vn1 - 1;
triangle.n2 = vn2 - 1;
triangle.tx0 = tx0 - 1;
triangle.tx1 = tx1 - 1;
triangle.tx2 = tx2 - 1;
list_append(Triangle, arena, model.triangles, triangle);
}
}
if (texture) {
model.texture = load_p6_image(arena, texture);
}
return model;
}
bool init_render(Arena *arena, Render *render, u64 width, u64 height) {
render->img = (Image){.width = width, .height = height};
if (!init_buffer(arena, &(render->img))) {
return false;
}
render->depth = (Depth){.width = width, .height = height};
if (!init_buffer(arena, &(render->depth))) {
return false;
}
f32 inf = -INFINITY;
clear_buffer(&(render->depth), &inf);
return true;
}
void render_model(const Model *model, Render *render, const Shader *shader,
RenderType render_type, Colour colour) {
Triangle triangle;
for (u64 i = 0; i < model->triangles->count; ++i) {
triangle = list_get(model->triangles, i);
render_triangle(&triangle, model, shader, render, render_type, colour);
}
}
internal void render_triangle(const Triangle *triangle, const Model *model,
const Shader *shader, Render *render,
RenderType render_type, Colour colour) {
Image *img = &(render->img);
V3f vertices[TRIANGLE_VERTICES] = {
list_get(model->vertices, triangle->p0),
list_get(model->vertices, triangle->p1),
list_get(model->vertices, triangle->p2),
};
V3f normals[TRIANGLE_VERTICES] = {
list_get(model->normals, triangle->n0),
list_get(model->normals, triangle->n1),
list_get(model->normals, triangle->n2),
};
V2f coordinates[TRIANGLE_VERTICES] = {
list_get(model->texture_coordinates, triangle->tx0),
list_get(model->texture_coordinates, triangle->tx1),
list_get(model->texture_coordinates, triangle->tx2),
};
for (u64 i = 0; i < TRIANGLE_VERTICES; ++i) {
vertices[i] = shader->vertex(&vertices[i], shader->model_view,
shader->projection, &render->img);
}
if (render_type == RENDER_TYPE_WIREFRAME) {
V3f v0, v1;
u64 x0, y0, x1, y1;
for (u64 i = 0; i < TRIANGLE_VERTICES; ++i) {
v0 = vertices[i];
v1 = vertices[(i + 1) % TRIANGLE_VERTICES];
draw_line(img, (u64)v0.x, (u64)v0.y, (u64)v1.x, (u64)v1.y, colour);
}
} else if (render_type == RENDER_TYPE_FILLED ||
render_type == RENDER_TYPE_SHADED) {
fill_triangle(render, vertices, normals, coordinates, colour,
model->texture, render_type);
}
}
internal void fill_triangle(Render *render, V3f vertices[TRIANGLE_VERTICES],
V3f normals[TRIANGLE_VERTICES],
V2f coordinates[TRIANGLE_VERTICES], Colour colour,
Image *texture, RenderType type) {
Image *img = &(render->img);
Depth *depth = &(render->depth);
TriangleBBox bbox = get_triangle_bbox(img, vertices);
V3f v0 = vertices[0];
V3f v1 = vertices[1];
V3f v2 = vertices[2];
V2i ab = V2(V2i, i64, v0.x, v0.y, v1.x, v1.y);
V2i ac = V2(V2i, i64, v0.x, v0.y, v2.x, v2.y);
f32 d00 = dot_v2(ab, ab);
f32 d01 = dot_v2(ab, ac);
f32 d11 = dot_v2(ac, ac);
f32 denom = d00 * d11 - d01 * d01;
V2i ap;
V3f coords;
f32 z;
f32 zbuf;
f32 nx, ny, nz;
V3f normal;
f32 tx_u, tx_v;
u64 tx_x, tx_y;
f32 intensity = 1.0f;
for (u64 y = bbox.y0; y <= bbox.y1; ++y) {
for (u64 x = bbox.x0; x <= bbox.x1; ++x) {
ap = V2(V2i, i64, v0.x, v0.y, x, y);
coords = get_barycentric_coords(d00, d01, d11, denom, &ab, &ac, &ap);
if (coords.x < 0.0f || coords.y < 0.0f || coords.x + coords.y > 1.0f) {
continue;
}
z = 0.0f;
z += v0.z * coords.x + v1.z * coords.y + v2.z * coords.z;
zbuf = get_pixel(f32, &(render->depth), x, y);
if (z > zbuf) {
if (type == RENDER_TYPE_SHADED) {
nx = normals[0].x * coords.x + normals[1].x * coords.y +
normals[2].x * coords.z;
ny = normals[0].y * coords.x + normals[1].y * coords.y +
normals[2].y * coords.z;
nz = normals[0].z * coords.x + normals[1].z * coords.y +
normals[2].z * coords.z;
normal = (V3f){nx, ny, nz};
intensity = dot_v3(normal, g_light_dir);
}
if (intensity < 0.0f) {
intensity = 0.01f;
}
if (texture) {
tx_u = coordinates[0].u * coords.x + coordinates[1].u * coords.y +
coordinates[2].u * coords.z;
tx_v = coordinates[0].v * coords.x + coordinates[1].v * coords.y +
coordinates[2].v * coords.z;
tx_x = tx_u * texture->width;
tx_y = (1.0f - tx_v) * texture->height;
colour = get_pixel(Colour, texture, tx_x, tx_y);
}
colour.r *= intensity;
colour.g *= intensity;
colour.b *= intensity;
set_pixel(depth, x, y, &z);
set_pixel(img, x, y, &colour);
}
}
}
}
internal TriangleBBox get_triangle_bbox(const Image *img,
V3f vertices[TRIANGLE_VERTICES]) {
f32 x0 = min(vertices[0].x, min(vertices[1].x, vertices[2].x));
f32 x1 = max(vertices[0].x, max(vertices[1].x, vertices[2].x));
f32 y0 = min(vertices[0].y, min(vertices[1].y, vertices[2].y));
f32 y1 = max(vertices[0].y, max(vertices[1].y, vertices[2].y));
return (TriangleBBox){
.x0 = x0,
.y0 = y0,
.x1 = x1,
.y1 = y1,
};
}
internal V3f get_barycentric_coords(f32 d00, f32 d01, f32 d11, f32 denom,
const V2i *ab, const V2i *ac,
const V2i *ap) {
if (denom == 0.0f) {
return (V3f){-INFINITY, -INFINITY, -INFINITY};
}
f32 d20 = dot_v2((*ap), (*ab));
f32 d21 = dot_v2((*ap), (*ac));
f32 v = (d11 * d20 - d01 * d21) / denom;
f32 w = (d00 * d21 - d01 * d20) / denom;
f32 u = 1.0f - v - w;
return (V3f){v, w, u};
}
internal V3f get_viewport_vertex(const V3f *vertex, const Image *img) {
V4f vh = {.x = vertex->x, .y = 0.0f - vertex->y, .z = vertex->z, .w = 1.0f};
vh = mat4x4_mul_vec4(viewport(vh.x, vh.y, img->width, img->height), vh);
return project_vec4(vh);
}
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