X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?a=blobdiff_plain;f=src%2Fpolyfill.c;h=856ea5f2204c5f045174cfbd3763a10fb84b9092;hb=3eebc6b38f3ad1fd082ae9d4d3263c42c384951c;hp=a068295f6b6974528fa5e602d55b4b9283db8ac2;hpb=9123da2ff9583baa8a221deceb23436fcbfea7d9;p=gba_blender

diff --git a/src/polyfill.c b/src/polyfill.c
index a068295..856ea5f 100644
--- a/src/polyfill.c
+++ b/src/polyfill.c
@@ -41,6 +41,7 @@ void polyfill_flat(struct pvertex *varr, int vnum, unsigned char col)
 	int32_t x, y0, y1, dx, dy, slope, fx, fy;
 	short *tab, start, len;
 	unsigned char *fbptr;
+	uint16_t *pptr, pcol = ((uint16_t)col << 8) | (uint16_t)col;
 
 	vlast = varr + vnum - 1;
 	top = fbheight;
@@ -92,8 +93,176 @@ void polyfill_flat(struct pvertex *varr, int vnum, unsigned char col)
 		len = scantab[1][i] - start;
 
 		if(len > 0) {
-			memset(fbptr + start, col, len);
+			if(start & 1) {
+				pptr = (uint16_t*)(fbptr + (start & 0xfffe));
+				*pptr = (*pptr & 0xff) | ((uint16_t)col << 8);
+				len--;
+				start++;
+			}
+			pptr = (uint16_t*)(fbptr + start);
+			while(len > 1) {
+				*pptr++ = pcol;
+				len -= 2;
+			}
+			if(len) {
+				*pptr = (*pptr & 0xff00) | col;
+			}
 		}
 		fbptr += fbwidth;
 	}
 }
+
+
+/* ----- line drawing and clipping ------ */
+enum {
+	IN		= 0,
+	LEFT	= 1,
+	RIGHT	= 2,
+	TOP		= 4,
+	BOTTOM	= 8
+};
+
+static int outcode(int x, int y, int xmin, int ymin, int xmax, int ymax)
+{
+	int code = 0;
+
+	if(x < xmin) {
+		code |= LEFT;
+	} else if(x > xmax) {
+		code |= RIGHT;
+	}
+	if(y < ymin) {
+		code |= TOP;
+	} else if(y > ymax) {
+		code |= BOTTOM;
+	}
+	return code;
+}
+
+#define FIXMUL(a, b)	(((a) * (b)) >> 8)
+#define FIXDIV(a, b)	(((a) << 8) / (b))
+
+#define LERP(a, b, t)	((a) + FIXMUL((b) - (a), (t)))
+
+int clip_line(int *x0, int *y0, int *x1, int *y1, int xmin, int ymin, int xmax, int ymax)
+{
+	int oc_out;
+
+	int oc0 = outcode(*x0, *y0, xmin, ymin, xmax, ymax);
+	int oc1 = outcode(*x1, *y1, xmin, ymin, xmax, ymax);
+
+	long fx0, fy0, fx1, fy1, fxmin, fymin, fxmax, fymax;
+
+	if(!(oc0 | oc1)) return 1;	/* both points are inside */
+
+	fx0 = *x0 << 8;
+	fy0 = *y0 << 8;
+	fx1 = *x1 << 8;
+	fy1 = *y1 << 8;
+	fxmin = xmin << 8;
+	fymin = ymin << 8;
+	fxmax = xmax << 8;
+	fymax = ymax << 8;
+
+	for(;;) {
+		long x, y, t;
+
+		if(oc0 & oc1) return 0;		/* both have points with the same outbit, not visible */
+		if(!(oc0 | oc1)) break;		/* both points are inside */
+
+		oc_out = oc0 ? oc0 : oc1;
+
+		if(oc_out & TOP) {
+			t = FIXDIV(fymin - fy0, fy1 - fy0);
+			x = LERP(fx0, fx1, t);
+			y = fymin;
+		} else if(oc_out & BOTTOM) {
+			t = FIXDIV(fymax - fy0, fy1 - fy0);
+			x = LERP(fx0, fx1, t);
+			y = fymax;
+		} else if(oc_out & LEFT) {
+			t = FIXDIV(fxmin - fx0, fx1 - fx0);
+			x = fxmin;
+			y = LERP(fy0, fy1, t);
+		} else {/*if(oc_out & RIGHT) {*/
+			t = FIXDIV(fxmax - fx0, fx1 - fx0);
+			x = fxmax;
+			y = LERP(fy0, fy1, t);
+		}
+
+		if(oc_out == oc0) {
+			fx0 = x;
+			fy0 = y;
+			oc0 = outcode(fx0 >> 8, fy0 >> 8, xmin, ymin, xmax, ymax);
+		} else {
+			fx1 = x;
+			fy1 = y;
+			oc1 = outcode(fx1 >> 8, fy1 >> 8, xmin, ymin, xmax, ymax);
+		}
+	}
+
+	*x0 = fx0 >> 8;
+	*y0 = fy0 >> 8;
+	*x1 = fx1 >> 8;
+	*y1 = fy1 >> 8;
+	return 1;
+}
+
+#define PUTPIXEL(ptr) \
+	do { \
+		uint16_t *pptr = (uint16_t*)((uint32_t)ptr & 0xfffffffe); \
+		if((uint32_t)ptr & 1) { \
+			*pptr = (*pptr & 0xff) | (color << 8); \
+		} else { \
+			*pptr = (*pptr & 0xff00) | color; \
+		} \
+	} while(0)
+
+void draw_line(int x0, int y0, int x1, int y1, unsigned short color)
+{
+	int i, dx, dy, x_inc, y_inc, error;
+	unsigned char *fbptr = fb;
+
+	fbptr += y0 * fbwidth + x0;
+
+	dx = x1 - x0;
+	dy = y1 - y0;
+
+	if(dx >= 0) {
+		x_inc = 1;
+	} else {
+		x_inc = -1;
+		dx = -dx;
+	}
+	if(dy >= 0) {
+		y_inc = fbwidth;
+	} else {
+		y_inc = -fbwidth;
+		dy = -dy;
+	}
+
+	if(dx > dy) {
+		error = dy * 2 - dx;
+		for(i=0; i<=dx; i++) {
+			PUTPIXEL(fbptr);
+			if(error >= 0) {
+				error -= dx * 2;
+				fbptr += y_inc;
+			}
+			error += dy * 2;
+			fbptr += x_inc;
+		}
+	} else {
+		error = dx * 2 - dy;
+		for(i=0; i<=dy; i++) {
+			PUTPIXEL(fbptr);
+			if(error >= 0) {
+				error -= dy * 2;
+				fbptr += x_inc;
+			}
+			error += dx * 2;
+			fbptr += y_inc;
+		}
+	}
+}
+