From 13aadb42819766b73d4f3b287abd74223c8f9029 Mon Sep 17 00:00:00 2001
From: Abdelrahman Said <said.abdelrahman89@gmail.com>
Date: Sun, 14 Jan 2024 02:44:35 +0000
Subject: [PATCH] Add utility functions and fix bug when reallocating lines
 array

---
 src/drawing.c | 52 +++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 40 insertions(+), 12 deletions(-)

diff --git a/src/drawing.c b/src/drawing.c
index 367b58e..720eb5f 100644
--- a/src/drawing.c
+++ b/src/drawing.c
@@ -8,6 +8,22 @@
 
 #define square(x) (x * x)
 
+typedef struct line line_t;
+struct line {
+  point_t p0;
+  point_t p1;
+};
+
+typedef struct triangle triangle_t;
+struct triangle {
+  point_t p0;
+  point_t p1;
+  point_t p2;
+};
+
+INTERNAL void draw_line(SDL_Renderer *renderer, line_t ln);
+INTERNAL void draw_triangle(SDL_Renderer *renderer, triangle_t triangle);
+
 bool init_arrows_arr(arrows_t *lines, u64 capacity) {
   u64 size = capacity * sizeof(arrow_t);
 
@@ -36,6 +52,8 @@ void add_arrow(arrows_t *lines, arrow_t ln) {
       lines->lines = ptr;
       return;
     }
+
+    lines->capacity = new_capacity;
   }
 
   lines->lines[(lines->count)++] = (arrow_t){
@@ -57,8 +75,9 @@ INTERNAL f32 vec2_magnitude(const vec2_t *vec) {
   return sqrtf((f32)vec->x * vec->x + (f32)vec->y * vec->y);
 }
 
-INTERNAL void draw_arrow_head(SDL_Renderer *renderer, const arrow_t *arrow,
-                              const point_t *arrow_end) {
+INTERNAL triangle_t calculate_arrow_head(SDL_Renderer *renderer,
+                                         const arrow_t *arrow,
+                                         const point_t *arrow_end) {
   // m = line_slope
   // dx = change_in_x
   // dy = change_in_y
@@ -129,14 +148,7 @@ INTERNAL void draw_arrow_head(SDL_Renderer *renderer, const arrow_t *arrow,
     arrow_base_p1.y = arrow_end->y + perpendicular_dy;
   }
 
-  SDL_RenderDrawLine(renderer, arrow_end->x, arrow_end->y, arrow_base_p0.x,
-                     arrow_base_p0.y);
-  SDL_RenderDrawLine(renderer, arrow_end->x, arrow_end->y, arrow_base_p1.x,
-                     arrow_base_p1.y);
-  SDL_RenderDrawLine(renderer, arrow_tip.x, arrow_tip.y, arrow_base_p0.x,
-                     arrow_base_p0.y);
-  SDL_RenderDrawLine(renderer, arrow_tip.x, arrow_tip.y, arrow_base_p1.x,
-                     arrow_base_p1.y);
+  return (triangle_t){arrow_tip, arrow_base_p0, arrow_base_p1};
 }
 
 void draw_arrow(SDL_Renderer *renderer, const arrow_t *arrow, colour_t colour) {
@@ -147,10 +159,26 @@ void draw_arrow(SDL_Renderer *renderer, const arrow_t *arrow, colour_t colour) {
       arrow->origin.x + arrow->direction.x,
       arrow->origin.y + arrow->direction.y,
   };
+  line_t line = (line_t){arrow->origin, end};
 
   if (vec2_magnitude(&(arrow->direction)) != 0) {
-    draw_arrow_head(renderer, arrow, &end);
+    triangle_t triangle = calculate_arrow_head(renderer, arrow, &end);
+    draw_triangle(renderer, triangle);
   }
 
-  SDL_RenderDrawLine(renderer, arrow->origin.x, arrow->origin.y, end.x, end.y);
+  draw_line(renderer, line);
+}
+
+INTERNAL void draw_line(SDL_Renderer *renderer, line_t ln) {
+  SDL_RenderDrawLine(renderer, ln.p0.x, ln.p0.y, ln.p1.x, ln.p1.y);
+}
+
+INTERNAL void draw_triangle(SDL_Renderer *renderer, triangle_t triangle) {
+  line_t ln0 = (line_t){triangle.p0, triangle.p1};
+  line_t ln1 = (line_t){triangle.p0, triangle.p2};
+  line_t ln2 = (line_t){triangle.p1, triangle.p2};
+
+  draw_line(renderer, ln0);
+  draw_line(renderer, ln1);
+  draw_line(renderer, ln2);
 }