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Calculate projection matrix from eye and target

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Abdelrahman Said 2024-08-17 22:04:33 +01:00
parent a3f0be461b
commit 3bbab3f624
2 changed files with 28 additions and 17 deletions
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src/obj.c
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@ -12,7 +12,6 @@
#include <string.h>
#define TRIANGLE_VERTICES 3
#define CAMERA_DISTANCE 5.0f
#define DEPTH_MAX 255
#define V2(T, ELEM_T, X0, Y0, X1, Y1) \
@ -23,9 +22,10 @@
#define dot_v2(V1, V2) ((f32)V1.x * (f32)V2.x + (f32)V1.y * (f32)V2.y)
#define dot_v3(V1, V2) \
((f32)V1.x * (f32)V2.x + (f32)V1.y * (f32)V2.y + (f32)V1.z * (f32)V2.z)
#define magnitude_v3(V) (sqrtf(dot_v3(V, V)))
#define normalise_v3(V) \
do { \
f32 magnitude = sqrtf(dot_v3(V, V)); \
f32 magnitude = magnitude_v3(V); \
V.x /= magnitude; \
V.y /= magnitude; \
V.z /= magnitude; \
@ -108,6 +108,7 @@ internal void fill_triangle(Render *render, V3f vertices[TRIANGLE_VERTICES],
Image *texture, RenderType type);
internal M4x4f lookat(V3f eye, V3f target, V3f up);
internal M4x4f viewport(f32 x, f32 y, u64 w, u64 h);
internal M4x4f projection(f32 coeff);
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,
@ -116,19 +117,10 @@ internal V3f get_barycentric_coords(f32 d00, f32 d01, f32 d11, f32 denom,
internal V3f get_viewport_vertex(const V3f *vertex, const Image *img);
V3f g_light_dir = {0.0f, 0.0f, 1.0f};
// clang-format off
M4x4f g_cam_matrix = {
.row0 = {1.0f, 0.0f, 0.0f, 0.0f},
.row1 = {0.0f, 1.0f, 0.0f, 0.0f},
.row2 = {0.0f, 0.0f, 1.0f, 0.0f},
.row3 = {0.0f, 0.0f, -1.0f / CAMERA_DISTANCE, 1.0f},
};
// clang-format on
V3f g_eye = {0.2f, 0.1f, 0.7f};
V3f g_eye = {0.2f, 0.1f, 0.75f};
V3f g_target = {0};
V3f g_up = {0.0f, 1.0f, 0.0f};
M4x4f g_cam_matrix = mat4x4_identity;
Model load_obj_file(Arena *arena, const char *filename, const char *texture) {
if (!arena) {
@ -225,10 +217,17 @@ bool init_render(Arena *arena, Render *render, u64 width, u64 height) {
void render_model(const Model *model, Render *render, Colour colour,
RenderType type, ColourType colour_type,
ProjectionType projection) {
ProjectionType projection_type) {
Triangle triangle;
M4x4f model_view = lookat(g_eye, g_target, g_up);
// Calculate projection matrix
V3f cam = V3(V3f, f32, g_target.x, g_target.y, g_target.z, g_eye.x, g_eye.y,
g_eye.z);
normalise_v3(cam);
f32 coeff = -1.0f / magnitude_v3(cam) * 0.5f;
g_cam_matrix = projection(coeff);
for (u64 i = 0; i < model->triangles->count; ++i) {
triangle = list_get(model->triangles, i);
if (colour_type == COLOUR_TYPE_RANDOM) {
@ -237,14 +236,14 @@ void render_model(const Model *model, Render *render, Colour colour,
.b = rand() % UINT8_MAX,
.a = 255};
}
render_triangle(&triangle, model, render, colour, type, projection,
render_triangle(&triangle, model, render, colour, type, projection_type,
model_view);
}
}
internal void render_triangle(const Triangle *triangle, const Model *model,
Render *render, Colour colour, RenderType type,
ProjectionType projection, M4x4f mv) {
ProjectionType projection_type, M4x4f mv) {
Image *img = &(render->img);
V3f vertices[TRIANGLE_VERTICES] = {
list_get(model->vertices, triangle->p0),
@ -276,8 +275,9 @@ internal void render_triangle(const Triangle *triangle, const Model *model,
}
// Basic perspective projection
if (projection == PROJECTION_TYPE_PERSPECTIVE) {
if (projection_type == PROJECTION_TYPE_PERSPECTIVE) {
V4f vertex;
for (u64 i = 0; i < TRIANGLE_VERTICES; ++i) {
vertex = (V4f){
.x = vertices[i].x,
@ -431,6 +431,17 @@ internal M4x4f viewport(f32 x, f32 y, u64 w, u64 h) {
return output;
}
internal M4x4f projection(f32 coeff) {
// clang-format off
return (M4x4f){
.row0 = {1.0f, 0.0f, 0.0f, 0.0f},
.row1 = {0.0f, 1.0f, 0.0f, 0.0f},
.row2 = {0.0f, 0.0f, 1.0f, 0.0f},
.row3 = {0.0f, 0.0f, coeff, 1.0f},
};
// clang-format on
}
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));