Improve implementation of drawing the noodles

include/math_utils.h

@@ -0,0 +1,9 @@
+#ifndef MATH_UTILS_H
+#define MATH_UTILS_H
+
+#include "aliases/aliases.h"
+
+i32 min(i32 a, i32 b);
+i32 max(i32 a, i32 b);
+
+#endif // !MATH_UTILS_H

include/ui.h

@@ -57,6 +57,7 @@ bool ui_button(const window *wnd, ui_ctx *ctx, rect rect,
                ui_elem_colours colours);
 rect ui_node(const window *wnd, ui_ctx *ctx, rect rect,
              ui_elem_colours colours);
-quad ui_quad(const window *wnd, ui_ctx *ctx, quad qd, ui_elem_colours colours);
+line ui_noodle(const window *wnd, ui_ctx *ctx, line ln,
+               ui_elem_colours colours);
 
 #endif // !UI_H

src/compositor.c

@@ -76,6 +76,11 @@ i32 run_main_loop(void) {
 
   i32 toolbox_button_x = (toolbox->width - BUTTON_WIDTH) / 2;
 
+  line ln = (line){
+      (point){20, 40},
+      (point){60, 200},
+  };
+
   while (comp.running) {
     while (SDL_PollEvent(&(comp.event))) {
       handle_ui_events(&(comp.windows[comp.active_window - 1]), &(comp.ctx),
@@ -152,6 +157,8 @@ i32 run_main_loop(void) {
                                   comp.nodes[i].colours);
     }
 
+    ln = ui_noodle(main_window, &(comp.ctx), ln, op_node_colours);
+
     for (u64 i = 0; i < MAX_WINDOWS; ++i) {
       swap_buffers(&(comp.windows[i]));
     }

src/math_utils.c

@@ -0,0 +1,5 @@
+#include "math_utils.h"
+
+i32 min(i32 a, i32 b) { return a <= b ? a : b; }
+
+i32 max(i32 a, i32 b) { return a >= b ? a : b; }

src/ui.c

@@ -1,7 +1,13 @@
 #include "ui.h"
 #include "SDL_events.h"
 #include "aliases/aliases.h"
+#include "math_utils.h"
 #include "window.h"
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define NOODLE_WIDTH 2
 
 INTERNAL bool aabb(rect rec, i32 x, i32 y);
 
@@ -126,63 +132,79 @@ rect ui_node(const window *wnd, ui_ctx *ctx, rect rec,
   return rec;
 }
 
-quad ui_quad(const window *wnd, ui_ctx *ctx, quad qd, ui_elem_colours colours) {
+line ui_noodle(const window *wnd, ui_ctx *ctx, line ln,
+               ui_elem_colours colours) {
   if (ctx->count + 1 >= MAX_UI_ELEMENTS) {
-    return (quad){0};
+    return (line){0};
   }
 
   u64 id = (ctx->count)++;
 
-  fill_quad(wnd, qd, colours.fill);
+  bool horizontal = ln.p0.y == ln.p1.y;
+
+  rect bounding_box = (rect){0};
+
+  if (horizontal) {
+    i32 x = min(ln.p0.x, ln.p1.x);
+
+    bounding_box.topleft = (point){x, ln.p0.y};
+    bounding_box.w = abs(ln.p1.x - ln.p0.x);
+    bounding_box.h = NOODLE_WIDTH;
+
+    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},
+    };
+
+    fill_quad(wnd, qd, colours.fill);
+
+    i32 _min_x_1 = min(qd.p0.x, qd.p1.x);
+    i32 _min_x_2 = min(qd.p2.x, qd.p3.x);
+    i32 min_x = min(_min_x_1, _min_x_2);
+
+    i32 _max_x_1 = max(qd.p0.x, qd.p1.x);
+    i32 _max_x_2 = max(qd.p2.x, qd.p3.x);
+    i32 max_x = max(_max_x_1, _max_x_2);
+
+    i32 _min_y_1 = min(qd.p0.y, qd.p1.y);
+    i32 _min_y_2 = min(qd.p2.y, qd.p3.y);
+    i32 min_y = min(_min_y_1, _min_y_2);
+
+    i32 _max_y_1 = max(qd.p0.y, qd.p1.y);
+    i32 _max_y_2 = max(qd.p2.y, qd.p3.y);
+    i32 max_y = max(_max_y_1, _max_y_2);
+
+    bounding_box = (rect){
+        .topleft.x = min_x,
+        .topleft.y = min_y,
+        .w = max_x - min_x,
+        .h = max_y - min_y,
+    };
+  }
 
   if (wnd != ctx->wnd || (ctx->active >= 0 && ctx->active != id)) {
-    return qd;
+    return ln;
   }
 
   if (ctx->mouse_up) {
     ctx->hovered = ctx->active = -1;
     ctx->rel_x = ctx->rel_y = 0;
-    return qd;
+    return ln;
   }
 
   if (ctx->hovered == id && ctx->active == id) {
-    qd.p0.x += ctx->rel_x;
-    qd.p0.y += ctx->rel_y;
-    qd.p1.x += ctx->rel_x;
-    qd.p1.y += ctx->rel_y;
-    qd.p2.x += ctx->rel_x;
-    qd.p2.y += ctx->rel_y;
-    qd.p3.x += ctx->rel_x;
-    qd.p3.y += ctx->rel_y;
+    ln.p0.x += ctx->rel_x;
+    ln.p0.y += ctx->rel_y;
 
-    return qd;
+    return ln;
   }
 
-  i32 _min_x_1 = qd.p0.x < qd.p1.x ? qd.p0.x : qd.p1.x;
-  i32 _min_x_2 = qd.p2.x < qd.p3.x ? qd.p2.x : qd.p3.x;
-  i32 min_x = _min_x_1 < _min_x_2 ? _min_x_1 : _min_x_2;
-
-  i32 _max_x_1 = qd.p0.x > qd.p1.x ? qd.p0.x : qd.p1.x;
-  i32 _max_x_2 = qd.p2.x > qd.p3.x ? qd.p2.x : qd.p3.x;
-  i32 max_x = _max_x_1 > _max_x_2 ? _max_x_1 : _max_x_2;
-
-  i32 _min_y_1 = qd.p0.y < qd.p1.y ? qd.p0.y : qd.p1.y;
-  i32 _min_y_2 = qd.p2.y < qd.p3.y ? qd.p2.y : qd.p3.y;
-  i32 min_y = _min_y_1 < _min_y_2 ? _min_y_1 : _min_y_2;
-
-  i32 _max_y_1 = qd.p0.y > qd.p1.y ? qd.p0.y : qd.p1.y;
-  i32 _max_y_2 = qd.p2.y > qd.p3.y ? qd.p2.y : qd.p3.y;
-  i32 max_y = _max_y_1 > _max_y_2 ? _max_y_1 : _max_y_2;
-
-  rect rec = (rect){
-      .topleft.x = min_x,
-      .topleft.y = min_y,
-      .w = max_x - min_x,
-      .h = max_y - min_y,
-  };
-
-  if (!aabb(rec, ctx->mouse_x, ctx->mouse_y)) {
-    return qd;
+  if (!aabb(bounding_box, ctx->mouse_x, ctx->mouse_y)) {
+    return ln;
   }
 
   ctx->hovered = id;
@@ -191,7 +213,7 @@ quad ui_quad(const window *wnd, ui_ctx *ctx, quad qd, ui_elem_colours colours) {
     ctx->active = id;
   }
 
-  return qd;
+  return ln;
 }
 
 INTERNAL bool aabb(rect rec, i32 x, i32 y) {

src/window.c

@@ -1,5 +1,6 @@
 #include "window.h"
 #include "aliases/aliases.h"
+#include "math_utils.h"
 #include <SDL2/SDL_rect.h>
 #include <SDL2/SDL_render.h>
 #include <SDL2/SDL_video.h>
@@ -89,42 +90,44 @@ void draw_triangle(const window *wnd, triangle triangle, colour colour) {
   draw_line(wnd, &ln2, colour);
 }
 
-INTERNAL inline i32 min(i32 a, i32 b, i32 c) {
-  i32 _min = a <= b ? a : b;
-  return _min <= c ? _min : c;
+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;
+
+  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);
+
+  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;
 }
 
-INTERNAL inline i32 max(i32 a, i32 b, i32 c) {
-  i32 _max = a >= b ? a : b;
-  return _max >= c ? _max : c;
-}
-
-INTERNAL inline i32 half_space(i32 x1, i32 x2, i32 y1, i32 y2, i32 x, i32 y) {
-  return (x2 - x1) * (y - y1) - (y2 - y1) * (x - x1);
-}
-
-void fill_triangle(const window *wnd, triangle triangle, colour colour) {
-  // Basic triangle filling algorithm from
+void fill_triangle(const window *wnd, triangle tri, colour colour) {
+  // Basic triangle filling algorithm inspired by
   // https://web.archive.org/web/20050408192410/http://sw-shader.sourceforge.net/rasterizer.html
-  i32 x1 = triangle.p0.x;
-  i32 x2 = triangle.p1.x;
-  i32 x3 = triangle.p2.x;
+  // but uses barycentric coordinates instead of half space
+  i32 x1 = tri.p0.x;
+  i32 x2 = tri.p1.x;
+  i32 x3 = tri.p2.x;
 
-  i32 y1 = triangle.p0.y;
-  i32 y2 = triangle.p1.y;
-  i32 y3 = triangle.p2.y;
+  i32 y1 = tri.p0.y;
+  i32 y2 = tri.p1.y;
+  i32 y3 = tri.p2.y;
 
   // Find bounding rect
-  i32 min_x = min(x1, x2, x3);
-  i32 max_x = max(x1, x2, x3);
-  i32 min_y = min(y1, y2, y3);
-  i32 max_y = max(y1, y2, y3);
+  i32 min_x = min(min(x1, x2), x3);
+  i32 max_x = max(max(x1, x2), x3);
+  i32 min_y = min(min(y1, y2), y3);
+  i32 max_y = max(max(y1, y2), y3);
 
   for (i32 y = min_y; y < max_y; ++y) {
     for (i32 x = min_x; x < max_x; ++x) {
-      if (half_space(x2, x1, y2, y1, x, y) >= 0 &&
-          half_space(x3, x2, y3, y2, x, y) >= 0 &&
-          half_space(x1, x3, y1, y3, x, y) >= 0) {
+      if (inside_triangle(tri, (point){x, y})) {
         draw_point(wnd, (point){x, y}, colour);
       }
     }
@@ -144,8 +147,8 @@ void draw_quad(const window *wnd, quad qd, colour colour) {
 }
 
 void fill_quad(const window *wnd, quad qd, colour colour) {
-  triangle t0 = (triangle){qd.p3, qd.p1, qd.p0};
-  triangle t1 = (triangle){qd.p0, qd.p2, qd.p3};
+  triangle t0 = (triangle){qd.p0, qd.p1, qd.p2};
+  triangle t1 = (triangle){qd.p1, qd.p2, qd.p3};
 
   fill_triangle(wnd, t0, colour);
   fill_triangle(wnd, t1, colour);