From 9d929c22baf0a5320d1be8ee62cd6b12e7c71647 Mon Sep 17 00:00:00 2001
From: Abdelrahman <said.abdelrahman89@gmail.com>
Date: Sun, 7 Jul 2024 23:19:12 +0100
Subject: [PATCH] Add clipping planes to the scene

---
 include/rasteriser/rasteriser.h | 10 ++++++++++
 src/rasteriser/main.c           | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/include/rasteriser/rasteriser.h b/include/rasteriser/rasteriser.h
index eccde20..05bbe37 100644
--- a/include/rasteriser/rasteriser.h
+++ b/include/rasteriser/rasteriser.h
@@ -51,11 +51,21 @@ typedef struct {
   transform_t transform;
 } instance_t;
 
+typedef struct {
+  vec3f_t normal;
+  f32 distance;
+} clipping_plane_t;
+
 typedef struct {
   u64 instance_count;
   instance_t *instances;
   camera_t *camera;
   const mat3x4f_t *proj_matrix;
+  clipping_plane_t near;
+  clipping_plane_t left;
+  clipping_plane_t right;
+  clipping_plane_t bottom;
+  clipping_plane_t top;
 } rasteriser_scene_t;
 
 void render_scene(window_t *wnd, Arena *arena, const rasteriser_scene_t *scene);
diff --git a/src/rasteriser/main.c b/src/rasteriser/main.c
index 202cd7e..a4bc802 100644
--- a/src/rasteriser/main.c
+++ b/src/rasteriser/main.c
@@ -8,6 +8,7 @@
 #include "window/window.h"
 #include <SDL2/SDL_events.h>
 #include <SDL2/SDL_keycode.h>
+#include <math.h>
 #include <stdlib.h>
 
 int main(void) {
@@ -97,11 +98,40 @@ int main(void) {
       (vec4f_t){0.0f, 0.0f, 1.0f, 0.0f},
   };
 
+  f32 sqrt_2 = sqrtf(2.0f);
+  f32 one_div_sqrt_2 = 1.0f / sqrt_2;
+  f32 neg_one_div_sqrt_2 = -1.0f / sqrt_2;
+
   rasteriser_scene_t scene = {
       .instance_count = ARR_LEN(instances),
       .instances = instances,
       .camera = &camera,
       .proj_matrix = &proj_matrix,
+      .near =
+          (clipping_plane_t){
+              .normal = (vec3f_t){0.0f, 0.0f, 1.0f},
+              .distance = viewport.z,
+          },
+      .left =
+          (clipping_plane_t){
+              .normal = (vec3f_t){one_div_sqrt_2, 0.0f, one_div_sqrt_2},
+              .distance = 0.0f,
+          },
+      .right =
+          (clipping_plane_t){
+              .normal = (vec3f_t){neg_one_div_sqrt_2, 0.0f, one_div_sqrt_2},
+              .distance = 0.0f,
+          },
+      .bottom =
+          (clipping_plane_t){
+              .normal = (vec3f_t){0.0f, one_div_sqrt_2, one_div_sqrt_2},
+              .distance = 0.0f,
+          },
+      .top =
+          (clipping_plane_t){
+              .normal = (vec3f_t){0.0f, neg_one_div_sqrt_2, one_div_sqrt_2},
+              .distance = 0.0f,
+          },
   };
 
   bool running = true;
@@ -141,7 +171,7 @@ int main(void) {
 
     clear_window(&window, bg);
 
-    render_scene(&window, arena, &scene);
+    render_scene(&window, frame_arena, &scene);
 
     swap_buffers(&window);