From edee7f1f66e7df2110069057289210c6bfbd272f Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Thu, 15 Apr 2021 16:00:56 +0200
Subject: Add rectangle drawing routines

---
 src/main.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 71 insertions(+), 4 deletions(-)

diff --git a/src/main.c b/src/main.c
index 7f04f28..32c4170 100644
--- a/src/main.c
+++ b/src/main.c
@@ -71,9 +71,12 @@ rgb15(u32 red, u32 green, u32 blue ) {
     return (blue << 10) | (green << 5) | red;
 }
 
-#define COLOR_RED  rgb15(31, 0, 12)
-#define COLOR_BLUE rgb15(2, 15, 30)
-#define COLOR_CYAN rgb15(0, 30, 30)
+#define COLOR_RED   rgb15(31, 0, 12)
+#define COLOR_BLUE  rgb15(2, 15, 30)
+#define COLOR_CYAN  rgb15(0, 30, 30)
+#define COLOR_GREY  rgb15(10, 10, 10)
+#define COLOR_BLACK rgb15(0, 0, 0)
+#define COLOR_WHITE rgb15(28, 28, 28)
 
 // Using bd-font, an 8x8 bitmap font.
 static inline void
@@ -165,6 +168,55 @@ draw_line(int x0, int y0, int x1, int y1, Color clr) {
     }
 }
 
+static inline void
+draw_rect(int x0, int y0, int x1, int y1, Color clr) {
+    if (x0 > x1) {
+        int tmp = x0;
+        x0 = x1;
+        x1 = tmp;
+    }
+    if (y0 > y1) {
+        int tmp = y0;
+        y0 = y1;
+        y1 = tmp;
+    }
+    int dx = x1 - x0;
+    int dy = y1 - y0;
+    for (size_t i = 0; i <= dx; ++i) {
+        int x = x0 + i;
+        FRAMEBUFFER[y0][x] = clr;
+        FRAMEBUFFER[y1][x] = clr;
+    }
+    for (size_t j = 0; j <= dy; ++j) {
+        int y = y0 + j;
+        FRAMEBUFFER[y][x0] = clr;
+        FRAMEBUFFER[y][x1] = clr;
+    }
+}
+
+static inline void
+draw_fill_rect(int x0, int y0, int x1, int y1, Color clr) {
+    if (x0 > x1) {
+        int tmp = x0;
+        x0 = x1;
+        x1 = tmp;
+    }
+    if (y0 > y1) {
+        int tmp = y0;
+        y0 = y1;
+        y1 = tmp;
+    }
+    int dx = x1 - x0;
+    int dy = y1 - y0;
+    for (size_t i = 0; i <= dx; ++i) {
+        for (size_t j = 0; j <= dy; ++j) {
+            int x = x0 + i;
+            int y = y0 + j;
+            FRAMEBUFFER[y][x] = clr;
+        }
+    }
+}
+
 static inline void
 wait_vsync() {
     while(DISP_VCOUNT >= 160);
@@ -178,7 +230,23 @@ wait_vsync() {
 int main(void) {
     set_display_mode(DISP_MODE_3 | DISP_BG2);
 
+    // Rectangle drawing testing.
+    Color clr = COLOR_WHITE;
+    for (size_t j = 0; j < SCREEN_HEIGHT; j += 8) {
+        clr = clr == COLOR_WHITE ? COLOR_BLACK : COLOR_WHITE;
+        for (size_t i = 0; i < SCREEN_WIDTH; i += 8) {
+            clr = clr == COLOR_WHITE ? COLOR_BLACK : COLOR_WHITE;
+            draw_fill_rect(i, j, 0 + i + 7, j + 7, clr);
+        }
+    }
+    clr = COLOR_GREY;
+    for (size_t j = 8; j < SCREEN_HEIGHT - 8; j += 8) {
+        for (size_t i = 8; i < SCREEN_WIDTH - 8; i += 8) {
+            draw_rect(i, j, 0 + i + 8, j + 8, clr);
+        }
+    }
 
+    // Bresenham's testing
     put_text(8, 8, COLOR_RED, "Testing Bresenham's algorithm");
 
     for (size_t i = 70; i <= SCREEN_WIDTH - 70; i += 5) {
@@ -195,7 +263,6 @@ int main(void) {
         int y1 = SCREEN_HEIGHT - i;
         draw_line(x0, y0, x1, y1, COLOR_BLUE);
     }
-
     for (size_t i = 70; i <= SCREEN_WIDTH - 70; i += 10) {
         int x0 = i;
         int y0 = 30;
-- 
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