zbuffer partial implementation

[dosdemo] / src / 3dgfx / polytmpl.h

diff --git a/src/3dgfx/polytmpl.h b/src/3dgfx/polytmpl.h
index 2072e2b..01bbd01 100644 (file)
--- a/src/3dgfx/polytmpl.h
+++ b/src/3dgfx/polytmpl.h
@@ -12,6 +12,9 @@ static uint32_t SCANEDGE(struct pvertex *v0, struct pvertex *v1, struct pvertex
 #ifdef TEXMAP
        int32_t u, v, du, dv, uslope, vslope;
 #endif
+#ifdef ZBUF
+       int z, dz, zslope;
+#endif
        int32_t start_idx, end_idx;
 
        if(v0->y > v1->y) {
@@ -48,6 +51,11 @@ static uint32_t SCANEDGE(struct pvertex *v0, struct pvertex *v1, struct pvertex
        uslope = (du << 8) / dy;
        vslope = (dv << 8) / dy;
 #endif
+#ifdef ZBUF
+       z = v0->z;
+       dz = v1->z - v0->z;
+       zslope = (dz << 8) / dy;
+#endif
 
        start_idx = v0->y >> 8;
        end_idx = v1->y >> 8;
@@ -58,7 +66,6 @@ static uint32_t SCANEDGE(struct pvertex *v0, struct pvertex *v1, struct pvertex
                x += slope;
 #ifdef GOURAUD
                /* we'll store the color in the edge tables with COLOR_SHIFT extra bits of precision */
-               CHECKEDGE(i);
                edge[i].r = r;
                edge[i].g = g;
                edge[i].b = b;
@@ -66,18 +73,20 @@ static uint32_t SCANEDGE(struct pvertex *v0, struct pvertex *v1, struct pvertex
                g += gslope;
                b += bslope;
 #ifdef BLEND_ALPHA
-               CHECKEDGE(i);
                edge[i].a = a;
                a += aslope;
 #endif
 #endif /* GOURAUD */
 #ifdef TEXMAP
-               CHECKEDGE(i);
                edge[i].u = u;
                edge[i].v = v;
                u += uslope;
                v += vslope;
 #endif
+#ifdef ZBUF
+               edge[i].z = z;
+               z += zslope;
+#endif
        }
 
        return (uint32_t)start_idx | ((uint32_t)(end_idx - 1) << 16);
@@ -89,7 +98,7 @@ void POLYFILL(struct pvertex *pv, int nverts)
        int topidx = 0, botidx = 0, sltop = pfill_fb.height, slbot = 0;
        g3d_pixel color;
        /* the following variables are used for interpolating horizontally accros scanlines */
-#if defined(GOURAUD) || defined(TEXMAP)
+#if defined(GOURAUD) || defined(TEXMAP) || defined(ZBUF)
        int mid;
        int32_t dx, tmp;
 #else
@@ -105,6 +114,9 @@ void POLYFILL(struct pvertex *pv, int nverts)
 #ifdef TEXMAP
        int32_t u, v, du, dv, uslope, vslope;
 #endif
+#ifdef ZBUF
+       int z, dz, zslope;
+#endif
 
        for(i=1; i<nverts; i++) {
                if(pv[i].y < pv[topidx].y) topidx = i;
@@ -154,6 +166,10 @@ void POLYFILL(struct pvertex *pv, int nverts)
                                right[idx].u = pv[i1].u;
                                right[idx].v = pv[i1].v;
 #endif
+#ifdef ZBUF
+                               left[idx].z = pv[i0].z;
+                               right[idx].z = pv[i1].z;
+#endif
                                CHECKEDGE(idx);
                                if(idx > slbot) slbot = idx;
                                if(idx < sltop) sltop = idx;
@@ -217,12 +233,19 @@ void POLYFILL(struct pvertex *pv, int nverts)
        uslope = (du << 8) / dx;
        vslope = (dv << 8) / dx;
 #endif
+#ifdef ZBUF
+       dz = right[mid].z - left[mid].z;
+       zslope = (dz << 8) / dx;
+#endif
 #endif /* !defined(HIGH_QUALITY) */
 
        /* for each scanline ... */
        for(i=sltop; i<=slbot; i++) {
                g3d_pixel *pixptr;
                int32_t x;
+#ifdef ZBUF
+               uint16_t *zptr;
+#endif
 
                CHECKEDGE(i);
                x = left[i].x;
@@ -240,9 +263,13 @@ void POLYFILL(struct pvertex *pv, int nverts)
                u = left[i].u;
                v = left[i].v;
 #endif
+#ifdef ZBUF
+               z = left[i].z;
+               zptr = pfill_zbuf + i * pfill_fb.width + (x >> 8);
+#endif
                CHECKEDGE(i);
 
-#if defined(HIGH_QUALITY) && (defined(GOURAUD) || defined(TEXMAP))
+#if defined(HIGH_QUALITY) && (defined(GOURAUD) || defined(TEXMAP) || defined(ZBUF))
                if(!(dx = right[i].x - left[i].x)) dx = 256;
 
                CHECKEDGE(i);
@@ -264,6 +291,10 @@ void POLYFILL(struct pvertex *pv, int nverts)
                uslope = (du << 8) / dx;
                vslope = (dv << 8) / dx;
 #endif
+#ifdef ZBUF
+               dz = right[i].z - left[i].z;
+               zslope = (dz << 8) / dx;
+#endif
 #endif /* HIGH_QUALITY */
                CHECKEDGE(i);
 
@@ -278,6 +309,31 @@ void POLYFILL(struct pvertex *pv, int nverts)
 #ifdef BLEND_ALPHA
                        int alpha, inv_alpha;
 #endif
+
+#ifdef ZBUF
+                       int cz = z;
+                       z += zslope;
+
+                       if(z <= *zptr) {
+                               *zptr = z;
+                       } else {
+#ifdef GOURAUD
+                               r += rslope;
+                               g += gslope;
+                               b += bslope;
+#ifdef BLEND_ALPHA
+                               a += aslope;
+#endif
+#endif
+#ifdef TEXMAP
+                               u += uslope;
+                               v += vslope;
+#endif
+                               goto skip_pixel;
+                       }
+                       zptr++;
+#endif
+
 #ifdef GOURAUD
                        /* we upped the color precision to while interpolating the
                         * edges, now drop the extra bits before packing
@@ -351,6 +407,9 @@ void POLYFILL(struct pvertex *pv, int nverts)
                        color = G3D_PACK_RGB(cr, cg, cb);
 #endif
 
+#ifdef ZBUF
+skip_pixel:
+#endif
 #ifdef DEBUG_OVERDRAW
                        *pixptr++ += DEBUG_OVERDRAW;
 #else