Initial implementation of bounding sphere clipping
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@ -40,6 +40,8 @@ typedef struct {
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list_vec3f_t *vertices;
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list_scene_triangle_t *triangles;
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} model_t;
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#define NULL_MODEL ((model_t){0})
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#define IS_NULL_MODEL(MODEL) (MODEL.vertices == NULL && MODEL.triangles == NULL)
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typedef struct {
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f32 scale;
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@ -47,6 +49,11 @@ typedef struct {
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vec3f_t position;
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} transform_t;
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typedef struct {
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vec3f_t centre;
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f32 radius;
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} bounding_sphere_t;
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typedef struct {
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model_t *model;
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transform_t transform;
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@ -57,21 +64,16 @@ typedef struct {
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f32 distance;
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} clipping_plane_t;
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#define CLIPPING_PLANE_COUNT 5
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typedef struct {
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u64 instance_count;
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instance_t *instances;
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camera_t *camera;
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const mat3x4f_t *proj_matrix;
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clipping_plane_t near;
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clipping_plane_t left;
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clipping_plane_t right;
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clipping_plane_t bottom;
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clipping_plane_t top;
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clipping_plane_t planes[CLIPPING_PLANE_COUNT];
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} rasteriser_scene_t;
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void render_scene(window_t *wnd, Arena *arena, const rasteriser_scene_t *scene);
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void render_instance(window_t *wnd, Arena *arena, mat4x4f_t camera_matrix,
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mat3x4f_t projection_matrix, const instance_t *instance);
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void draw_wireframe_triangle(window_t *wnd, Arena *arena, triangle_t triangle);
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void draw_filled_triangle(window_t *wnd, Arena *arena, triangle_t triangle);
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void draw_shaded_triangle(window_t *wnd, Arena *arena, triangle_t triangle);
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@ -107,30 +107,35 @@ int main(void) {
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.instances = instances,
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.camera = &camera,
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.proj_matrix = &proj_matrix,
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.near =
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(clipping_plane_t){
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.normal = (vec3f_t){0.0f, 0.0f, 1.0f},
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.distance = viewport.z,
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},
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.left =
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(clipping_plane_t){
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.normal = (vec3f_t){one_div_sqrt_2, 0.0f, one_div_sqrt_2},
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.distance = 0.0f,
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},
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.right =
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(clipping_plane_t){
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.normal = (vec3f_t){neg_one_div_sqrt_2, 0.0f, one_div_sqrt_2},
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.distance = 0.0f,
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},
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.bottom =
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(clipping_plane_t){
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.normal = (vec3f_t){0.0f, one_div_sqrt_2, one_div_sqrt_2},
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.distance = 0.0f,
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},
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.top =
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(clipping_plane_t){
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.normal = (vec3f_t){0.0f, neg_one_div_sqrt_2, one_div_sqrt_2},
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.distance = 0.0f,
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.planes =
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{
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[0] =
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(clipping_plane_t){
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.normal = (vec3f_t){0.0f, 0.0f, 1.0f},
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.distance = viewport.z,
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},
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[1] =
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(clipping_plane_t){
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.normal = (vec3f_t){one_div_sqrt_2, 0.0f, one_div_sqrt_2},
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.distance = 0.0f,
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},
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[2] =
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(clipping_plane_t){
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.normal =
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(vec3f_t){neg_one_div_sqrt_2, 0.0f, one_div_sqrt_2},
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.distance = 0.0f,
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},
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[3] =
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(clipping_plane_t){
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.normal = (vec3f_t){0.0f, one_div_sqrt_2, one_div_sqrt_2},
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.distance = 0.0f,
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},
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[4] =
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(clipping_plane_t){
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.normal =
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(vec3f_t){0.0f, neg_one_div_sqrt_2, one_div_sqrt_2},
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.distance = 0.0f,
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},
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},
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};
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@ -11,8 +11,17 @@
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#include <string.h>
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#include <sys/mman.h>
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internal void render_instance(window_t *wnd, const rasteriser_scene_t *scene,
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Arena *arena, mat4x4f_t camera_matrix,
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mat3x4f_t projection_matrix,
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const instance_t *instance);
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internal void clip_instance(model_t *model, const rasteriser_scene_t *scene);
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internal list_float *interpolate(Arena *arena, i32 i0, f32 d0, i32 i1, f32 d1);
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internal inline void order_triangle_points(triangle_t *triangle);
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internal inline bounding_sphere_t
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get_bounding_sphere(const list_vec3f_t *vertices);
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internal inline f32 signed_distance(const vec3f_t *vertex,
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const clipping_plane_t *plane);
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void render_scene(window_t *wnd, Arena *arena,
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const rasteriser_scene_t *scene) {
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@ -24,15 +33,17 @@ void render_scene(window_t *wnd, Arena *arena,
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mul_mat4x4f(cam_inverse_rotation, cam_inverse_translation);
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for (u64 i = 0; i < scene->instance_count; ++i) {
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render_instance(wnd, arena, cam_matrix, *(scene->proj_matrix),
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render_instance(wnd, scene, arena, cam_matrix, *(scene->proj_matrix),
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&(scene->instances[i]));
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}
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}
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void render_instance(window_t *wnd, Arena *arena, mat4x4f_t camera_matrix,
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mat3x4f_t projection_matrix, const instance_t *instance) {
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list_vec4f_t *transformed = list_create_with_capacity(
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vec4f_t, arena, instance->model->vertices->count * sizeof(vec4f_t));
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internal void render_instance(window_t *wnd, const rasteriser_scene_t *scene,
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Arena *arena, mat4x4f_t camera_matrix,
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mat3x4f_t projection_matrix,
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const instance_t *instance) {
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list_vec3f_t *transformed = list_create_with_capacity(
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vec3f_t, arena, instance->model->vertices->count * sizeof(vec3f_t));
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if (!transformed) {
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return;
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}
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@ -51,9 +62,20 @@ void render_instance(window_t *wnd, Arena *arena, mat4x4f_t camera_matrix,
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vec4f_t xf_vertex = {0};
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for (u64 i = 0; i < instance->model->vertices->count; ++i) {
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vertex = list_get(instance->model->vertices, i);
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xf_vertex = mul_mat4x4f_by_vec4f(
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xf_cam_mat, (vec4f_t){vertex.x, vertex.y, vertex.z, 1.0f});
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list_append(vec4f_t, arena, transformed, xf_vertex);
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xf_vertex = vec_div_num(vec4f_t, xf_vertex, xf_vertex.w);
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vertex = (vec3f_t){xf_vertex.x, xf_vertex.y, xf_vertex.z};
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list_append(vec3f_t, arena, transformed, vertex);
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}
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model_t model = {transformed, instance->model->triangles};
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clip_instance(&model, scene);
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if (IS_NULL_MODEL(model)) {
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return;
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}
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list_vec2i_t *projected = list_create_with_capacity(
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@ -64,8 +86,9 @@ void render_instance(window_t *wnd, Arena *arena, mat4x4f_t camera_matrix,
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vec2i_t point = {0};
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for (u64 i = 0; i < transformed->count; ++i) {
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xf_vertex = list_get(transformed, i);
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vertex = mul_mat3x4f_by_vec4f(projection_matrix, xf_vertex);
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vertex = list_get(transformed, i);
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vertex = mul_mat3x4f_by_vec4f(
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projection_matrix, (vec4f_t){vertex.x, vertex.y, vertex.z, 1.0f});
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point = (vec2i_t){(i32)(vertex.x / vertex.z), (i32)(vertex.y / vertex.z)};
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list_append(vec2i_t, arena, projected, point);
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}
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@ -238,6 +261,22 @@ void draw_line(window_t *wnd, Arena *arena, line_t line, colour_t colour) {
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}
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}
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internal void clip_instance(model_t *model, const rasteriser_scene_t *scene) {
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bounding_sphere_t sphere = get_bounding_sphere(model->vertices);
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f32 distance = 0.0;
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f32 neg_radius = -1.0f * sphere.radius;
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const clipping_plane_t *plane = NULL;
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for (u64 i = 0; i < CLIPPING_PLANE_COUNT; ++i) {
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plane = &(scene->planes[i]);
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distance = signed_distance(&(sphere.centre), plane);
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if (distance < neg_radius) {
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*model = NULL_MODEL;
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}
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}
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}
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internal list_float *interpolate(Arena *arena, i32 i0, f32 d0, i32 i1, f32 d1) {
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list_float *values;
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if (i0 == i1) {
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@ -279,3 +318,32 @@ internal inline void order_triangle_points(triangle_t *triangle) {
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swap(f32, triangle->h1, triangle->h2);
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}
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}
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internal inline bounding_sphere_t
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get_bounding_sphere(const list_vec3f_t *vertices) {
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vec3f_t sum = {0};
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for (u64 i = 0; i < vertices->count; ++i) {
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sum = vec_add(vec3f_t, list_get(vertices, i), sum);
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}
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vec3f_t centre = vec_div_num(vec3f_t, sum, vertices->count);
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f32 radius = 0.0f;
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f32 tmp = 0.0f;
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vec3f_t dst = {0};
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for (u64 i = 0; i < vertices->count; ++i) {
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dst = vec_sub(vec3f_t, list_get(vertices, i), centre);
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tmp = vec_magnitude(vec3f_t, dst);
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radius = tmp > radius ? tmp : radius;
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}
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return (bounding_sphere_t){
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.centre = centre,
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.radius = radius,
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};
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}
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internal inline f32 signed_distance(const vec3f_t *vertex,
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const clipping_plane_t *plane) {
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return (vertex->x * plane->normal.x) + (vertex->y + plane->normal.y) +
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(vertex->z + plane->normal.z) + plane->distance;
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}
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