From aae737d17d128a382f4408049c2b3d1d253169bc Mon Sep 17 00:00:00 2001
From: Scott Duensing <scott@kangaroopunch.com>
Date: Sun, 7 Jan 2024 19:36:35 -0600
Subject: [PATCH] Slightly optimized cube.

---
 examples/cube/cube.c | 50 +++++++++++++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 15 deletions(-)

diff --git a/examples/cube/cube.c b/examples/cube/cube.c
index d6b0170..9fd3d5b 100644
--- a/examples/cube/cube.c
+++ b/examples/cube/cube.c
@@ -97,10 +97,22 @@ int32_t SIN[] = { 0, 6, 12, 18, 25, 31, 37, 43, 50, 56, 62, 68, 75, 81, 87, 93,
 			  509, 510, 510, 511, 511, 511, 511, 511
 };
 
+typedef struct lineS {
+	int16_t x1;
+	int16_t y1;
+	int16_t x2;
+	int16_t y2;
+} lineT;
+
 int32_t *COS = SIN + COS_OFF;
+uint16_t width;
+uint16_t height;
+int32_t  a     = TO_FIX(4);
+int32_t  scale = TO_FIX(40);
+lineT    past[24][2];
 
 
-void draw_cube(int16_t t) {
+void draw_cube(byte p, int16_t t) {
 
 	static const int16_t edges[] = {
 		0, 1,  1, 3,  3, 2,  2, 0,
@@ -128,18 +140,13 @@ void draw_cube(int16_t t) {
 	int32_t  cubeProjX[8];
 	int32_t  cubeProjY[8];
 	int16_t  i;
+	byte     l;
 	int16_t  e1;
 	int16_t  e2;
 	int16_t  x1;
 	int16_t  y1;
 	int16_t  x2;
 	int16_t  y2;
-	uint16_t width;
-	uint16_t height;
-	int32_t  a     = TO_FIX(4);
-	int32_t  scale = TO_FIX(40);
-
-	bitmapGetResolution(&width, &height);
 
     for (i=0; i<8; ++i) {
         // Rotation around Y
@@ -158,23 +165,34 @@ void draw_cube(int16_t t) {
         cubeProjY[i] = fix_div(fix_mul(a, cubeRotY[i]), cubeRotZ[i]);
     }
 
+    l = 0;
     for (i=0; i<24; i += 2) {
         e1 = edges[i];
         e2 = edges[i + 1];
-        x1 = TO_LONG(fix_mul(cubeProjX[e1], scale)) + (width >> 1);
-        y1 = TO_LONG(fix_mul(cubeProjY[e1], scale)) + (height >> 1);
-        x2 = TO_LONG(fix_mul(cubeProjX[e2], scale)) + (width >> 1);
-        y2 = TO_LONG(fix_mul(cubeProjY[e2], scale)) + (height >> 1);
+        x1 = TO_LONG(fix_mul(cubeProjX[e1], scale)) + width;
+        y1 = TO_LONG(fix_mul(cubeProjY[e1], scale)) + height;
+        x2 = TO_LONG(fix_mul(cubeProjX[e2], scale)) + width;
+        y2 = TO_LONG(fix_mul(cubeProjY[e2], scale)) + height;
+        past[l][p].x1 = x1;
+        past[l][p].y1 = y1;
+        past[l][p].x2 = x2;
+        past[l][p].y2 = y2;
+        l++;
         bitmapLine(x1, y1, x2, y2);
     }
 }
 
 int main(void) {
-	int16_t t = 0;
-	byte    p = 0;
+	byte    i;
+	int16_t t  = 0;
+	byte    p  = 0;
 
 	f256Init();
 
+	bitmapGetResolution(&width, &height);
+	width  = width >> 1;
+	height = height >> 1;
+
 	while(1) {
 		if (p) {
 			p = 0;
@@ -186,9 +204,11 @@ int main(void) {
 			bitmapShowPage(1);
 		}
 		bitmapSetColor(0);
-		bitmapClear();
+		for (i=0; i<12; i++) {
+			bitmapLine(past[i][p].x1, past[i][p].y1, past[i][p].x2, past[i][p].y2);
+		}
 		bitmapSetColor(255);
-		draw_cube(t);
+		draw_cube(p, t);
 		t += 2;
 	}