nuclear@5: #include "config.h"
nuclear@5: #include <string.h>
nuclear@6: #include <assert.h>
nuclear@5: #include "polyfill.h"
nuclear@5: #include "fixed.h"
nuclear@5: #include "gbasys.h"
nuclear@5: 
nuclear@9: #define VNEXT(x, n)		(((x) + 1) % (n))
nuclear@9: #define VPREV(x, n)		((x) > 0 ? (x) - 1 : (n) - 1)
nuclear@9: 
nuclear@9: static void fill_scanline_pal(int y, int x0, int x1, uint8_t color);
nuclear@9: static void fill_scanline_rgb(int y, int x0, int x1, uint16_t color);
nuclear@14: static int winding(int32_t x0, int32_t y0, int32_t x1, int32_t y1);
nuclear@5: 
nuclear@5: void draw_poly(int num, const pvec3 *verts, uint16_t color)
nuclear@5: {
nuclear@5: 	int i, topidx = 0, botidx = 0;
nuclear@9: 	int lidx[2] = {-1, -1}, ridx[2] = {-1, -1};
nuclear@5: 	int32_t y, topy, boty;
nuclear@9: 	int32_t ldy = 0, rdy = 0, ldxdy, rdxdy;
nuclear@5: 	int32_t lx, rx;
nuclear@5: 	int start, end;
nuclear@14: 	pvec3 v0, v1;
nuclear@14: 
nuclear@14: 	v0.x = verts[1].x - verts[0].x;
nuclear@14: 	v0.y = verts[1].y - verts[0].y;
nuclear@14: 
nuclear@14: 	v1.x = verts[2].x - verts[0].x;
nuclear@14: 	v1.y = verts[2].y - verts[0].y;
nuclear@14: 
nuclear@14: 	if(winding(v0.x, v0.y, v1.x, v1.y) < 0) {
nuclear@14: 		return;	/* backface */
nuclear@14: 	}
nuclear@5: 
nuclear@5: 	topy = boty = verts[0].y;
nuclear@5: 	for(i=1; i<num; i++) {
nuclear@5: 		int32_t y = verts[i].y;
nuclear@5: 		if(y < topy) {
nuclear@5: 			topy = y;
nuclear@5: 			topidx = i;
nuclear@5: 		}
nuclear@5: 		if(y > boty) {
nuclear@5: 			boty = y;
nuclear@5: 			botidx = i;
nuclear@5: 		}
nuclear@5: 	}
nuclear@5: 
nuclear@5: 	lidx[0] = ridx[0] = topidx;
nuclear@9: 
nuclear@9: 	/* find starting left edge */
nuclear@9: 	lidx[1] = VPREV(lidx[0], num);
nuclear@9: 	ldy = verts[lidx[1]].y - verts[lidx[0]].y;
nuclear@9: 
nuclear@9: 	while(ldy == 0) {
nuclear@9: 		lidx[0] = lidx[1];
nuclear@9: 		lidx[1] = VPREV(lidx[1], num);
nuclear@9: 
nuclear@9: 		if(lidx[1] == topidx) {
nuclear@9: 			return;	/* degenerate */
nuclear@9: 		}
nuclear@9: 
nuclear@9: 		ldy = verts[lidx[1]].y - verts[lidx[0]].y;
nuclear@9: 	}
nuclear@9: 	lx = verts[lidx[0]].x;
nuclear@9: 	ldxdy = x16div(verts[lidx[1]].x - lx, ldy);
nuclear@9: 
nuclear@9: 	/* find starting right edge */
nuclear@9: 	ridx[1] = VNEXT(ridx[0], num);
nuclear@9: 	rdy = verts[ridx[1]].y - verts[ridx[0]].y;
nuclear@9: 
nuclear@9: 	while(rdy == 0) {
nuclear@9: 		ridx[0] = ridx[1];
nuclear@9: 		ridx[1] = VNEXT(ridx[1], num);
nuclear@9: 
nuclear@9: 		if(ridx[1] == topidx) {
nuclear@9: 			return; /* degenerate */
nuclear@9: 		}
nuclear@9: 
nuclear@9: 		rdy = verts[ridx[1]].y - verts[ridx[0]].y;
nuclear@9: 	}
nuclear@9: 	rx = verts[ridx[0]].x;
nuclear@9: 	rdxdy = x16div(verts[ridx[1]].x - rx, rdy);
nuclear@9: 
nuclear@5: 	start = topy >> 16;
nuclear@5: 	end = boty >> 16;
nuclear@5: 
nuclear@6: 	if(end >= HEIGHT) end = HEIGHT - 1;
nuclear@6: 
nuclear@5: 	y = topy;
nuclear@14: 	for(i=start; i<=end; i++) {
nuclear@9: 		short x0, x1;
nuclear@5: 
nuclear@5: 		if(y >= verts[lidx[1]].y) {
nuclear@9: 			lx = verts[lidx[1]].x;
nuclear@5: 			lidx[0] = lidx[1];
nuclear@9: 			lidx[1] = VPREV(lidx[1], num);
nuclear@5: 			ldy = verts[lidx[1]].y - verts[lidx[0]].y;
nuclear@5: 			if(ldy < 0) {
nuclear@5: 				break;
nuclear@5: 			}
nuclear@14: 			if(ldy) {
nuclear@14: 				ldxdy = x16div(verts[lidx[1]].x - lx, ldy);
nuclear@14: 			} else {
nuclear@14: 				ldxdy = verts[lidx[1]].x - lx;
nuclear@14: 			}
nuclear@5: 		}
nuclear@5: 		if(y >= verts[ridx[1]].y) {
nuclear@9: 			rx = verts[ridx[1]].x;
nuclear@5: 			ridx[0] = ridx[1];
nuclear@9: 			ridx[1] = VNEXT(ridx[1], num);
nuclear@5: 			rdy = verts[ridx[1]].y - verts[ridx[0]].y;
nuclear@5: 			if(rdy < 0) {
nuclear@5: 				break;
nuclear@5: 			}
nuclear@14: 			if(rdy) {
nuclear@14: 				rdxdy = x16div(verts[ridx[1]].x - rx, rdy);
nuclear@14: 			} else {
nuclear@14: 				rdxdy = verts[ridx[1]].x - rx;
nuclear@14: 			}
nuclear@5: 		}
nuclear@5: 
nuclear@14: 		x0 = lx >> 16;
nuclear@14: 		x1 = rx >> 16;
nuclear@9: 
nuclear@14: 		if(i >= 0) {// && x0 < x1) {
nuclear@9: #ifdef PALMODE
nuclear@9: 			fill_scanline_pal(i, x0, x1, (uint8_t)color);
nuclear@9: #else
nuclear@9: 			fill_scanline_rgb(i, x0, x1, color);
nuclear@9: #endif
nuclear@9: 		}
nuclear@9: 
nuclear@5: 		lx += ldxdy;
nuclear@5: 		rx += rdxdy;
nuclear@6: 		y += 65536;
nuclear@5: 	}
nuclear@5: }
nuclear@5: 
nuclear@9: 
nuclear@9: static void fill_scanline_pal(int y, int x0, int x1, uint8_t color)
nuclear@9: {
nuclear@9: #if 1
nuclear@9: 	int i, num_pairs, num_pix = x1 - x0;
nuclear@9: 	uint16_t *pixels = (uint16_t*)back_buffer->pixels + (y * WIDTH + x0) / 2;
nuclear@9: 	uint16_t colpair = (uint16_t)color | ((uint16_t)color << 8);
nuclear@9: 
nuclear@9: 	if(x0 & 1) {
nuclear@9: 		uint16_t pix = *pixels & 0xff;
nuclear@9: 		*pixels++ = pix | ((uint16_t)color << 8);
nuclear@9: 		--num_pix;
nuclear@9: 	}
nuclear@9: 
nuclear@9: 	num_pairs = (num_pix & 0xfffe) / 2;
nuclear@9: 
nuclear@9: 	for(i=0; i<num_pairs; i++) {
nuclear@9: 		*pixels++ = colpair;
nuclear@9: 	}
nuclear@9: 
nuclear@9: 	if(num_pix & 1) {
nuclear@9: 		uint16_t pix = *pixels & 0xff00;
nuclear@9: 		*pixels = pix | color;
nuclear@9: 	}
nuclear@9: #else
nuclear@9: 	int i;
nuclear@9: 	uint8_t *pixels = (uint8_t*)back_buffer->pixels + y * WIDTH + x0;
nuclear@9: 
nuclear@9: 	for(i=x0; i<x1; i++) {
nuclear@9: 		*pixels++ = color;
nuclear@9: 	}
nuclear@9: #endif
nuclear@9: }
nuclear@9: 
nuclear@9: static void fill_scanline_rgb(int y, int x0, int x1, uint16_t color)
nuclear@5: {
nuclear@5: 	int i;
nuclear@14: 	uint16_t *pixels;
nuclear@5: 
nuclear@14: 	if(x0 > x1) {
nuclear@14: 		i = x0;
nuclear@14: 		x0 = x1;
nuclear@14: 		x1 = i;
nuclear@14: 	}
nuclear@14: 
nuclear@14: 	if(x0 < 0) x0 = 0;
nuclear@14: 	if(x1 >= WIDTH - 1) x1 = WIDTH - 1;
nuclear@14: 
nuclear@14: 	pixels = (uint16_t*)back_buffer->pixels + y * WIDTH + x0;
nuclear@5: 	for(i=x0; i<x1; i++) {
nuclear@5: 		*pixels++ = color;
nuclear@5: 	}
nuclear@5: }
nuclear@8: 
nuclear@8: 
nuclear@8: void draw_point(const pvec3 *v, uint16_t color)
nuclear@8: {
nuclear@8: 	int x = v->x >> 16;
nuclear@8: 	int y = v->y >> 16;
nuclear@8: 	uint16_t *pixels = (uint16_t*)back_buffer->pixels;
nuclear@8: 
nuclear@8: 	if(x < 0 || x >= WIDTH || y < 0 || y >= HEIGHT) {
nuclear@8: 		return;
nuclear@8: 	}
nuclear@8: 
nuclear@9: #ifdef PALMODE
nuclear@9: 	pixels += (y * WIDTH + x) / 2;
nuclear@9: 	if(x & 1) {
nuclear@9: 		*pixels = (*pixels & 0xff) | (color << 8);
nuclear@9: 	} else {
nuclear@9: 		*pixels = (*pixels & 0xff00) | color;
nuclear@9: 	}
nuclear@9: #else
nuclear@8: 	pixels[y * WIDTH + x] = color;
nuclear@9: #endif
nuclear@8: }
nuclear@14: 
nuclear@14: static int winding(int32_t x0, int32_t y0, int32_t x1, int32_t y1)
nuclear@14: {
nuclear@14: 	return x16mul(x0, y1) - x16mul(y0, x1);
nuclear@14: }