New triangle rasterization code. Store per-span initial/step values in the

new triangle_span struct.  Much cleaner code and possibilities for future
optimizations.

src/mesa/drivers/osmesa/osmesa.c

@@ -1,4 +1,4 @@
-/* $Id: osmesa.c,v 1.54 2001/05/10 12:22:32 keithw Exp $ */
+/* $Id: osmesa.c,v 1.55 2001/05/14 16:23:04 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -55,6 +55,7 @@
 #include "swrast/s_depth.h"
 #include "swrast/s_lines.h"
 #include "swrast/s_triangle.h"
+#include "swrast/s_trispan.h"
 #include "tnl/tnl.h"
 #include "tnl/t_context.h"
 #include "tnl/t_pipeline.h"
@@ -1600,21 +1601,24 @@ static void smooth_rgba_z_triangle( GLcontext *ctx,
 #define DEPTH_TYPE DEFAULT_SOFTWARE_DEPTH_TYPE
 #define INTERP_RGB 1
 #define INTERP_ALPHA 1
-#define INNER_LOOP( LEFT, RIGHT, Y )				\
-{								\
-   GLint i, len = RIGHT-LEFT;					\
-   GLchan *img = PIXELADDR4(LEFT, Y); 				\
-   for (i = 0; i < len; i++, img += 4) {			\
-      GLdepth z = FixedToDepth(ffz);				\
+#define RENDER_SPAN( span )					\
+   GLuint i;							\
+   GLchan *img = PIXELADDR4(span.x, span.y); 			\
+   for (i = 0; i < span.count; i++, img += 4) {			\
+      const GLdepth z = FixedToDepth(span.z);			\
       if (z < zRow[i]) {					\
-         PACK_RGBA(img, FixedToInt(ffr), FixedToInt(ffg),	\
-		        FixedToInt(ffb), FixedToInt(ffa));	\
+         PACK_RGBA(img, FixedToInt(span.red),			\
+            FixedToInt(span.green), FixedToInt(span.blue),	\
+            FixedToInt(span.alpha));				\
          zRow[i] = z;						\
       }								\
-      ffr += fdrdx;  ffg += fdgdx;  ffb += fdbdx;  ffa += fdadx;\
-      ffz += fdzdx;						\
-   }								\
-}
+      span.red += span.redStep;					\
+      span.green += span.greenStep;				\
+      span.blue += span.blueStep;				\
+      span.alpha += span.alphaStep;				\
+      span.z += span.zStep;					\
+   }
+
 #ifdef WIN32
 #include "..\swrast\s_tritemp.h"
 #else
@@ -1641,19 +1645,18 @@ static void flat_rgba_z_triangle( GLcontext *ctx,
    PACK_RGBA((GLchan *) &pixel, v0->color[0], v0->color[1],	\
                                 v0->color[2], v0->color[3]);
 
-#define INNER_LOOP( LEFT, RIGHT, Y )			\
-{							\
-   GLint i, len = RIGHT-LEFT;				\
-   GLuint *img = (GLuint *) PIXELADDR4(LEFT, Y);   	\
-   for (i=0;i<len;i++) {				\
-      GLdepth z = FixedToDepth(ffz);			\
+#define RENDER_SPAN( span )				\
+   GLuint i;						\
+   GLuint *img = (GLuint *) PIXELADDR4(span.x, span.y);	\
+   for (i = 0; i < span.count; i++) {			\
+      const GLdepth z = FixedToDepth(span.z);		\
       if (z < zRow[i]) {				\
          img[i] = pixel;				\
          zRow[i] = z;					\
       }							\
-      ffz += fdzdx;					\
-   }							\
-}
+      span.z += span.zStep;				\
+   }
+
 #ifdef WIN32
 #include "..\swrast\s_tritemp.h"
 #else

src/mesa/swrast/s_trispan.h

@@ -0,0 +1,79 @@
+/* $Id: s_trispan.h,v 1.1 2001/05/14 16:23:04 brianp Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version:  3.5
+ *
+ * Copyright (C) 1999-2001  Brian Paul   All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+#ifndef S_TRISPAN_H
+#define S_TRISPAN_H
+
+
+/*
+ * The triangle_span structure is used by the triangle template code in
+ * s_tritemp.h.  It describes how colors, Z, texcoords, etc are to be
+ * interpolated across each scanline of triangle.
+ * With this structure it's easy to hand-off span rasterization to a
+ * subroutine instead of doing it all inline like we used to do.
+ * It also cleans up the local variable namespace a great deal.
+ *
+ * It would be interesting to experiment with multiprocessor rasterization
+ * with this structure.  The triangle rasterizer could simply emit a
+ * stream of these structures which would be consumed by one or more
+ * span-processing threads which could run in parallel.
+ */
+
+
+#define SPAN_RGBA         0x01
+#define SPAN_SPEC         0x02
+#define SPAN_INDEX        0x04
+#define SPAN_Z            0x08
+#define SPAN_FOG          0x10
+#define SPAN_TEXTURE      0x20
+#define SPAN_INT_TEXTURE  0x40
+#define SPAN_LAMBDA       0x80
+
+
+struct triangle_span {
+   GLint x, y;
+   GLuint count;
+   GLuint activeMask;  /* OR of the SPAN_* flags */
+   GLfixed red, redStep;
+   GLfixed green, greenStep;
+   GLfixed blue, blueStep;
+   GLfixed alpha, alphaStep;
+   GLfixed specRed, specRedStep;
+   GLfixed specGreen, specGreenStep;
+   GLfixed specBlue, specBlueStep;
+   GLfixed index, indexStep;
+   GLfixed z, zStep;
+   GLfloat fog, fogStep;
+   GLfloat tex[MAX_TEXTURE_UNITS][4], texStep[MAX_TEXTURE_UNITS][4];
+   GLfixed intTex[2], intTexStep[2];
+   /* Needed for texture lambda (LOD) computation */
+   GLfloat rho[MAX_TEXTURE_UNITS];
+   GLfloat texWidth[MAX_TEXTURE_UNITS], texHeight[MAX_TEXTURE_UNITS];
+};
+
+
+#endif /* S_TRISPAN_H */