1 /* $Id: tmapflat.c,v 1.5 2003-02-18 20:15:48 btb Exp $ */
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17 * Flat shader derived from texture mapper (a little slow)
20 * Revision 1.13 1995/02/20 18:23:24 john
21 * Added new module for C versions of inner loops.
23 * Revision 1.12 1995/02/20 17:09:17 john
24 * Added code so that you can build the tmapper with no assembly!
26 * Revision 1.11 1994/11/30 00:58:01 mike
29 * Revision 1.10 1994/11/28 13:34:32 mike
32 * Revision 1.9 1994/11/19 15:21:46 mike
33 * rip out unused code.
35 * Revision 1.8 1994/11/12 16:41:41 mike
36 * *** empty log message ***
38 * Revision 1.7 1994/11/09 23:05:12 mike
39 * do lighting on texture maps which get flat shaded instead.
41 * Revision 1.6 1994/10/06 19:53:07 matt
42 * Added function that takes same parms as draw_tmap(), but renders flat
44 * Revision 1.5 1994/10/06 18:38:12 john
45 * Added the ability to fade a scanline by calling gr_upoly_tmap
46 * with Gr_scanline_darkening_level with a value < MAX_FADE_LEVELS.
48 * Revision 1.4 1994/05/25 18:46:32 matt
49 * Added gr_upoly_tmap_ylr(), which generates ylr's for a polygon
51 * Revision 1.3 1994/04/08 16:25:58 mike
52 * Comment out some includes (of header files)
53 * call init_interface_vars_to_assembler.
55 * Revision 1.2 1994/03/31 08:33:44 mike
56 * Fixup flat shading version of texture mapper (get it?)
57 * (Or maybe not, I admit to not testing my code...hahahah!)
59 * Revision 1.1 1993/09/08 17:29:10 mike
77 //#include "tmapext.h"
81 void (*scanline_func)(int,fix,fix);
83 // -------------------------------------------------------------------------------------
84 // Texture map current scanline.
85 // Uses globals Du_dx and Dv_dx to incrementally compute u,v coordinates
86 // -------------------------------------------------------------------------------------
87 void tmap_scanline_flat(int y, fix xleft, fix xright)
92 // setup to call assembler scanline renderer
95 fx_xleft = f2i(xleft);
96 fx_xright = f2i(xright);
98 if ( Gr_scanline_darkening_level >= GR_FADE_LEVELS )
99 cur_tmap_scanline_flat();
101 tmap_flat_shade_value = Gr_scanline_darkening_level;
102 cur_tmap_scanline_shaded();
107 //--unused-- void tmap_scanline_shaded(int y, fix xleft, fix xright)
111 //--unused-- dx = xright - xleft;
113 //--unused-- // setup to call assembler scanline renderer
115 //--unused-- fx_y = y << 16;
116 //--unused-- fx_xleft = xleft;
117 //--unused-- fx_xright = xright;
119 //--unused-- asm_tmap_scanline_shaded();
123 // -------------------------------------------------------------------------------------
124 // Render a texture map.
125 // Linear in outer loop, linear in inner loop.
126 // -------------------------------------------------------------------------------------
127 void texture_map_flat(g3ds_tmap *t, int color)
129 int vlt,vrt,vlb,vrb; // vertex left top, vertex right top, vertex left bottom, vertex right bottom
131 fix dx_dy_left,dx_dy_right;
139 tmap_flat_color = color;
141 // Determine top and bottom y coords.
142 compute_y_bounds(t,&vlt,&vlb,&vrt,&vrb,&max_y_vertex);
144 // Set top and bottom (of entire texture map) y coordinates.
145 topy = f2i(v3d[vlt].y2d);
146 boty = f2i(v3d[max_y_vertex].y2d);
148 // Set amount to change x coordinate for each advance to next scanline.
149 dy = f2i(t->verts[vlb].y2d) - f2i(t->verts[vlt].y2d);
150 if (dy < FIX_RECIP_TABLE_SIZE)
151 recip_dy = fix_recip[dy];
155 dx_dy_left = compute_dx_dy(t,vlt,vlb, recip_dy);
157 dy = f2i(t->verts[vrb].y2d) - f2i(t->verts[vrt].y2d);
158 if (dy < FIX_RECIP_TABLE_SIZE)
159 recip_dy = fix_recip[dy];
163 dx_dy_right = compute_dx_dy(t,vrt,vrb, recip_dy);
165 // Set initial values for x, u, v
166 xleft = v3d[vlt].x2d;
167 xright = v3d[vrt].x2d;
169 // scan all rows in texture map from top through first break.
170 // @mk: Should we render the scanline for y==boty? This violates Matt's spec.
172 for (y = topy; y < boty; y++) {
174 // See if we have reached the end of the current left edge, and if so, set
175 // new values for dx_dy and x,u,v
176 if (y == f2i(v3d[vlb].y2d)) {
177 // Handle problem of double points. Search until y coord is different. Cannot get
178 // hung in an infinite loop because we know there is a vertex with a lower y coordinate
179 // because in the for loop, we don't scan all spanlines.
180 while (y == f2i(v3d[vlb].y2d)) {
182 vlb = prevmod(vlb,t->nv);
184 dy = f2i(t->verts[vlb].y2d) - f2i(t->verts[vlt].y2d);
185 if (dy < FIX_RECIP_TABLE_SIZE)
186 recip_dy = fix_recip[dy];
190 dx_dy_left = compute_dx_dy(t,vlt,vlb, recip_dy);
192 xleft = v3d[vlt].x2d;
195 // See if we have reached the end of the current left edge, and if so, set
196 // new values for dx_dy and x. Not necessary to set new values for u,v.
197 if (y == f2i(v3d[vrb].y2d)) {
198 while (y == f2i(v3d[vrb].y2d)) {
200 vrb = succmod(vrb,t->nv);
203 dy = f2i(t->verts[vrb].y2d) - f2i(t->verts[vrt].y2d);
204 if (dy < FIX_RECIP_TABLE_SIZE)
205 recip_dy = fix_recip[dy];
209 dx_dy_right = compute_dx_dy(t,vrt,vrb, recip_dy);
211 xright = v3d[vrt].x2d;
215 //tmap_scanline_flat(y, xleft, xright);
216 (*scanline_func)(y, xleft, xright);
219 xright += dx_dy_right;
222 //tmap_scanline_flat(y, xleft, xright);
223 (*scanline_func)(y, xleft, xright);
227 // -----------------------------------------------------------------------------------------
228 // This is the gr_upoly-like interface to the texture mapper which uses texture-mapper compatible
229 // (ie, avoids cracking) edge/delta computation.
230 void gr_upoly_tmap(int nverts, int *vert )
232 gr_upoly_tmap_ylr(nverts, vert, tmap_scanline_flat);
238 typedef struct pnt2d {
243 #pragma off (unreferenced) //bp not referenced
246 //this takes the same partms as draw_tmap, but draws a flat-shaded polygon
247 void draw_tmap_flat(grs_bitmap *bp,int nverts,g3s_point **vertbuf)
249 pnt2d points[MAX_TMAP_VERTS];
254 Assert(nverts < MAX_TMAP_VERTS);
256 average_light = vertbuf[0]->p3_l;
257 for (i=1; i<nverts; i++)
258 average_light += vertbuf[i]->p3_l;
261 average_light = f2i(average_light * NUM_LIGHTING_LEVELS/4);
263 average_light = f2i(average_light * NUM_LIGHTING_LEVELS/nverts);
265 if (average_light < 0)
267 else if (average_light > NUM_LIGHTING_LEVELS-1)
268 average_light = NUM_LIGHTING_LEVELS-1;
270 color = gr_fade_table[average_light*256 + bp->avg_color];
273 for (i=0;i<nverts;i++) {
274 points[i].x = vertbuf[i]->p3_sx;
275 points[i].y = vertbuf[i]->p3_sy;
278 gr_upoly_tmap(nverts,(int *) points);
282 #pragma on (unreferenced)
285 // -----------------------------------------------------------------------------------------
286 //This is like gr_upoly_tmap() but instead of drawing, it calls the specified
287 //function with ylr values
288 void gr_upoly_tmap_ylr(int nverts, int *vert, void (*ylr_func)(int,fix,fix) )
293 //--now called from g3_start_frame-- init_interface_vars_to_assembler();
297 for (i=0; i<nverts; i++) {
298 my_tmap.verts[i].x2d = *vert++;
299 my_tmap.verts[i].y2d = *vert++;
302 scanline_func = ylr_func;
304 texture_map_flat(&my_tmap, COLOR);