Update noodle drawing code

compile

@@ -2,7 +2,7 @@
 
 CC=clang
 CFLAGS="-g -Wall -Iinclude -Iintern $(pkg-config --cflags sdl2)"
-LIBS="$(pkg-config --libs sdl2)"
+LIBS="$(pkg-config --libs sdl2) -lm"
 SRC=src/*.c
 OUT=main
 

include/math_utils.h

@@ -3,6 +3,8 @@
 
 #include "aliases/aliases.h"
 
+#define square(x) (x * x)
+
 i32 min(i32 a, i32 b);
 i32 max(i32 a, i32 b);
 

include/window.h

@@ -8,6 +8,7 @@
 #include <stdbool.h>
 
 typedef struct point point;
+typedef point vec2;
 typedef struct line line;
 typedef struct triangle triangle;
 typedef struct quad quad;
@@ -67,13 +68,17 @@ bool init_window(window *wnd, const char *title, u32 width, u32 height, i32 x,
 void cleanup_window(window *wnd);
 void clear_window(const window *wnd, colour colour);
 void swap_buffers(const window *wnd);
+
+vec2 line_direction(const line *ln);
+
 void draw_point(const window *wnd, point p, colour colour);
 void draw_line(const window *wnd, const line *ln, colour colour);
 void draw_triangle(const window *wnd, triangle triangle, colour colour);
-void fill_triangle(const window *wnd, triangle triangle, colour colour);
 void draw_quad(const window *wnd, quad qd, colour colour);
-void fill_quad(const window *wnd, quad qd, colour colour);
 void draw_rect(const window *wnd, rect rec, colour colour);
+
+void fill_triangle(const window *wnd, triangle triangle, colour colour);
+void fill_quad(const window *wnd, quad qd, colour colour);
 void fill_rect(const window *wnd, rect rec, colour colour);
 
 #endif // !WINDOW_H

src/compositor.c

@@ -77,8 +77,8 @@ i32 run_main_loop(void) {
   i32 toolbox_button_x = (toolbox->width - BUTTON_WIDTH) / 2;
 
   line ln = (line){
-      (point){20, 40},
-      (point){60, 200},
+      (point){80, 100},
+      (point){120, 300},
   };
 
   while (comp.running) {

src/ui.c

@@ -3,10 +3,11 @@
 #include "aliases/aliases.h"
 #include "math_utils.h"
 #include "window.h"
+#include <math.h>
 #include <stdbool.h>
 #include <stdlib.h>
 
-#define NOODLE_WIDTH 2
+#define NOODLE_HALF_WIDTH 2
 
 INTERNAL bool aabb(rect rec, i32 x, i32 y);
 
@@ -146,18 +147,37 @@ line ui_noodle(const window *wnd, ui_ctx *ctx, line ln,
   if (horizontal) {
     i32 x = min(ln.p0.x, ln.p1.x);
 
-    bounding_box.topleft = (point){x, ln.p0.y};
+    bounding_box.topleft = (point){x, ln.p0.y - NOODLE_HALF_WIDTH};
     bounding_box.w = abs(ln.p1.x - ln.p0.x);
-    bounding_box.h = NOODLE_WIDTH;
+    bounding_box.h = NOODLE_HALF_WIDTH * 2;
 
     fill_rect(wnd, bounding_box, colours.fill);
   } else {
-    quad qd = (quad){
-        .p0 = ln.p0,
-        .p1 = (point){ln.p0.x + NOODLE_WIDTH, ln.p0.y},
-        .p2 = ln.p1,
-        .p3 = (point){ln.p1.x + NOODLE_WIDTH, ln.p1.y},
-    };
+    vec2 direction = line_direction(&ln);
+
+    quad qd = (quad){0};
+
+    if (direction.x == 0) {
+      qd = (quad){
+          .p0 = (point){ln.p0.x - NOODLE_HALF_WIDTH, ln.p0.y},
+          .p1 = (point){ln.p0.x + NOODLE_HALF_WIDTH, ln.p0.y},
+          .p2 = (point){ln.p1.x - NOODLE_HALF_WIDTH, ln.p1.y},
+          .p3 = (point){ln.p1.x + NOODLE_HALF_WIDTH, ln.p1.y},
+      };
+    } else {
+      f32 slope = (f32)(direction.y) / direction.x;
+
+      f32 perpendicular_dy =
+          sqrtf(square(NOODLE_HALF_WIDTH) / (square((f32)slope) + 1.0f));
+      f32 perpendicular_dx = -1.0f * slope * perpendicular_dy;
+
+      qd = (quad){
+          .p0 = (point){ln.p0.x - perpendicular_dx, ln.p0.y - perpendicular_dy},
+          .p1 = (point){ln.p0.x + perpendicular_dx, ln.p0.y + perpendicular_dy},
+          .p2 = (point){ln.p1.x - perpendicular_dx, ln.p1.y - perpendicular_dy},
+          .p3 = (point){ln.p1.x + perpendicular_dx, ln.p1.y + perpendicular_dy},
+      };
+    }
 
     fill_quad(wnd, qd, colours.fill);
 

src/window.c

@@ -6,6 +6,8 @@
 #include <SDL2/SDL_video.h>
 #include <stdbool.h>
 
+INTERNAL inline bool inside_triangle(triangle tri, point p);
+
 bool init_window(window *wnd, const char *title, u32 width, u32 height, i32 x,
                  i32 y) {
   i32 pos_x = x >= 0 ? x : SDL_WINDOWPOS_CENTERED;
@@ -70,6 +72,13 @@ void clear_window(const window *wnd, colour colour) {
 
 void swap_buffers(const window *wnd) { SDL_RenderPresent(wnd->renderer); }
 
+vec2 line_direction(const line *ln) {
+  return (vec2){
+      .x = ln->p1.x - ln->p0.x,
+      .y = ln->p1.y - ln->p0.y,
+  };
+}
+
 void draw_point(const window *wnd, point p, colour colour) {
   set_colour(wnd, colour);
   SDL_RenderDrawPoint(wnd->renderer, p.x, p.y);
@@ -90,21 +99,24 @@ void draw_triangle(const window *wnd, triangle triangle, colour colour) {
   draw_line(wnd, &ln2, colour);
 }
 
-INTERNAL inline bool inside_triangle(triangle tri, point p) {
-  // Based on the following video:
-  // https://www.youtube.com/watch?v=HYAgJN3x4GA
-  f32 cy_min_ay = tri.p2.y - tri.p0.y;
-  f32 cx_min_ax = tri.p2.x - tri.p0.x;
-  f32 by_min_ay = tri.p1.y - tri.p0.y;
-  f32 bx_min_ax = tri.p1.x - tri.p0.x;
+void draw_rect(const window *wnd, rect rec, colour colour) {
+  set_colour(wnd, colour);
 
-  f32 w1 =
-      (tri.p0.x * cy_min_ay + (p.y - tri.p0.y) * cx_min_ax - p.x * cy_min_ay) /
-      (by_min_ay * cx_min_ax - bx_min_ax * cy_min_ay);
+  SDL_Rect dst = {rec.topleft.x, rec.topleft.y, rec.w, rec.h};
 
-  f32 w2 = (p.y - tri.p0.y - w1 * by_min_ay) / cy_min_ay;
+  SDL_RenderDrawRect(wnd->renderer, &dst);
+}
 
-  return w1 >= 0.0f && w2 >= 0.0f && (w1 + w2) <= 1.0f;
+void draw_quad(const window *wnd, quad qd, colour colour) {
+  line l0 = (line){qd.p0, qd.p1};
+  line l1 = (line){qd.p1, qd.p3};
+  line l2 = (line){qd.p3, qd.p2};
+  line l3 = (line){qd.p2, qd.p0};
+
+  draw_line(wnd, &l0, colour);
+  draw_line(wnd, &l1, colour);
+  draw_line(wnd, &l2, colour);
+  draw_line(wnd, &l3, colour);
 }
 
 void fill_triangle(const window *wnd, triangle tri, colour colour) {
@@ -134,16 +146,12 @@ void fill_triangle(const window *wnd, triangle tri, colour colour) {
   }
 }
 
-void draw_quad(const window *wnd, quad qd, colour colour) {
-  line l0 = (line){qd.p0, qd.p1};
-  line l1 = (line){qd.p1, qd.p3};
-  line l2 = (line){qd.p3, qd.p2};
-  line l3 = (line){qd.p2, qd.p0};
+void fill_rect(const window *wnd, rect rec, colour colour) {
+  set_colour(wnd, colour);
 
-  draw_line(wnd, &l0, colour);
-  draw_line(wnd, &l1, colour);
-  draw_line(wnd, &l2, colour);
-  draw_line(wnd, &l3, colour);
+  SDL_Rect dst = {rec.topleft.x, rec.topleft.y, rec.w, rec.h};
+
+  SDL_RenderFillRect(wnd->renderer, &dst);
 }
 
 void fill_quad(const window *wnd, quad qd, colour colour) {
@@ -154,18 +162,19 @@ void fill_quad(const window *wnd, quad qd, colour colour) {
   fill_triangle(wnd, t1, colour);
 }
 
-void draw_rect(const window *wnd, rect rec, colour colour) {
-  set_colour(wnd, colour);
+INTERNAL inline bool inside_triangle(triangle tri, point p) {
+  // Based on the following video:
+  // https://www.youtube.com/watch?v=HYAgJN3x4GA
+  f32 cy_min_ay = tri.p2.y - tri.p0.y;
+  f32 cx_min_ax = tri.p2.x - tri.p0.x;
+  f32 by_min_ay = tri.p1.y - tri.p0.y;
+  f32 bx_min_ax = tri.p1.x - tri.p0.x;
 
-  SDL_Rect dst = {rec.topleft.x, rec.topleft.y, rec.w, rec.h};
+  f32 w1 =
+      (tri.p0.x * cy_min_ay + (p.y - tri.p0.y) * cx_min_ax - p.x * cy_min_ay) /
+      (by_min_ay * cx_min_ax - bx_min_ax * cy_min_ay);
 
-  SDL_RenderDrawRect(wnd->renderer, &dst);
-}
-
-void fill_rect(const window *wnd, rect rec, colour colour) {
-  set_colour(wnd, colour);
-
-  SDL_Rect dst = {rec.topleft.x, rec.topleft.y, rec.w, rec.h};
-
-  SDL_RenderFillRect(wnd->renderer, &dst);
+  f32 w2 = (p.y - tri.p0.y - w1 * by_min_ay) / cy_min_ay;
+
+  return w1 >= 0.0f && w2 >= 0.0f && (w1 + w2) <= 1.0f;
 }