From aedaa7ade0ed623d09b18a34023f2e02201e67e6 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Fri, 4 Jun 2021 10:53:24 +0200
Subject: Add slow rect drawing primitive to renderer

---
 src/main.c     |  4 +++-
 src/renderer.c | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/main.c b/src/main.c
index 61547c8..ab41915 100644
--- a/src/main.c
+++ b/src/main.c
@@ -64,12 +64,14 @@ int main(void) {
     irq_init();
     irs_set(IRQ_VBLANK, irs_stub);
 
-    txt_drawf("Hello world: %d", 4, 4, 6, 10);
 
     // Main loop.
     PROF_INIT();
     while (true) {
         bios_vblank_wait();
+        txt_drawf("Hello world: %d", 4, 4, 6, 10);
+        draw_rect(30, 30, 45, 45, 1);
+        draw_rect(35, 35, 60, 40, 2);
         PROF_SHOW();
         PROF(flip_buffer(), flip_cycles);
     }
diff --git a/src/renderer.c b/src/renderer.c
index 076d698..4aa583d 100644
--- a/src/renderer.c
+++ b/src/renderer.c
@@ -44,6 +44,32 @@ draw_pixel(u16 x, u16 y, u8 color) {
     dirty_tiles[tile_y] |= 1 << tile_x;
 }
 
+IWRAM_CODE
+void
+draw_rect(int x0, int y0, int x1, int y1, u8 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;
+    // TODO: SLOW should be vectorized.
+    for (int i = 0; i <= dx; ++i) {
+        draw_pixel(x0 + i, y0, clr);
+        draw_pixel(x0 + i, y1, clr);
+    }
+    for (int i = 0; i <= dy; ++i) {
+        draw_pixel(x0, y0 + i, clr);
+        draw_pixel(x1, y0 + i, clr);
+    }
+}
+
 IWRAM_CODE
 void
 draw_tile(u16 x, u16 y, Tile *tile, bool merge) {
-- 
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