software rendering

[retroray] / src / gaw / polyfill.c

diff --git a/src/gaw/polyfill.c b/src/gaw/polyfill.c
index 250c152..15c06fb 100644 (file)
--- a/src/gaw/polyfill.c
+++ b/src/gaw/polyfill.c
@@ -1,3 +1,20 @@
+/*
+RetroRay - integrated standalone vintage modeller/renderer
+Copyright (C) 2023  John Tsiombikas <nuclear@mutantstargoat.com>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -398,3 +415,58 @@ void polyfill_add_tex_wire(struct pvertex *verts, int nverts)
 #include "polytmpl.h"
 #undef POLYFILL
 
+
+void draw_line(struct pvertex *verts)
+{
+       int32_t x0, y0, x1, y1;
+       int i, dx, dy, x_inc, y_inc, error;
+       uint32_t *fb = pfill_fb.pixels;
+       uint32_t color = PACK_RGB(verts[0].r, verts[0].g, verts[0].b);
+
+       x0 = verts[0].x >> 8;
+       y0 = verts[0].y >> 8;
+       x1 = verts[1].x >> 8;
+       y1 = verts[1].y >> 8;
+
+       fb += y0 * pfill_fb.width + x0;
+
+       dx = x1 - x0;
+       dy = y1 - y0;
+
+       if(dx >= 0) {
+               x_inc = 1;
+       } else {
+               x_inc = -1;
+               dx = -dx;
+       }
+       if(dy >= 0) {
+               y_inc = pfill_fb.width;
+       } else {
+               y_inc = -pfill_fb.width;
+               dy = -dy;
+       }
+
+       if(dx > dy) {
+               error = dy * 2 - dx;
+               for(i=0; i<=dx; i++) {
+                       *fb = color;
+                       if(error >= 0) {
+                               error -= dx * 2;
+                               fb += y_inc;
+                       }
+                       error += dy * 2;
+                       fb += x_inc;
+               }
+       } else {
+               error = dx * 2 - dy;
+               for(i=0; i<=dy; i++) {
+                       *fb = color;
+                       if(error >= 0) {
+                               error -= dy * 2;
+                               fb += x_inc;
+                       }
+                       error += dx * 2;
+                       fb += y_inc;
+               }
+       }
+}