s_triangle.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

/*
 * Mesa 3-D graphics library
 * Version:  6.5.3
 *
 * Copyright (C) 1999-2007  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.
 */


/*
 * When the device driver doesn't implement triangle rasterization it
 * can hook in _swrast_Triangle, which eventually calls one of these
 * functions to draw triangles.
 */

#include "glheader.h"
#include "context.h"
#include "colormac.h"
#include "imports.h"
#include "macros.h"
#include "texformat.h"

#include "s_aatriangle.h"
#include "s_context.h"
#include "s_feedback.h"
#include "s_span.h"
#include "s_triangle.h"


/*
 * Just used for feedback mode.
 */
GLboolean
_swrast_culltriangle( GLcontext *ctx,
                      const SWvertex *v0,
                      const SWvertex *v1,
                      const SWvertex *v2 )
{
   GLfloat ex = v1->attrib[FRAG_ATTRIB_WPOS][0] - v0->attrib[FRAG_ATTRIB_WPOS][0];
   GLfloat ey = v1->attrib[FRAG_ATTRIB_WPOS][1] - v0->attrib[FRAG_ATTRIB_WPOS][1];
   GLfloat fx = v2->attrib[FRAG_ATTRIB_WPOS][0] - v0->attrib[FRAG_ATTRIB_WPOS][0];
   GLfloat fy = v2->attrib[FRAG_ATTRIB_WPOS][1] - v0->attrib[FRAG_ATTRIB_WPOS][1];
   GLfloat c = ex*fy-ey*fx;

   if (c * SWRAST_CONTEXT(ctx)->_BackfaceCullSign > 0)
      return 0;

   return 1;
}



/*
 * Render a smooth or flat-shaded color index triangle.
 */
#define NAME ci_triangle
#define INTERP_Z 1
#define INTERP_ATTRIBS 1  /* just for fog */
#define INTERP_INDEX 1
#define RENDER_SPAN( span )  _swrast_write_index_span(ctx, &span);
#include "s_tritemp.h"



/*
 * Render a flat-shaded RGBA triangle.
 */
#define NAME flat_rgba_triangle
#define INTERP_Z 1
#define SETUP_CODE				\
   ASSERT(ctx->Texture._EnabledCoordUnits == 0);\
   ASSERT(ctx->Light.ShadeModel==GL_FLAT);	\
   span.interpMask |= SPAN_RGBA;		\
   span.red = ChanToFixed(v2->color[0]);	\
   span.green = ChanToFixed(v2->color[1]);	\
   span.blue = ChanToFixed(v2->color[2]);	\
   span.alpha = ChanToFixed(v2->color[3]);	\
   span.redStep = 0;				\
   span.greenStep = 0;				\
   span.blueStep = 0;				\
   span.alphaStep = 0;
#define RENDER_SPAN( span )  _swrast_write_rgba_span(ctx, &span);
#include "s_tritemp.h"



/*
 * Render a smooth-shaded RGBA triangle.
 */
#define NAME smooth_rgba_triangle
#define INTERP_Z 1
#define INTERP_RGB 1
#define INTERP_ALPHA 1
#define SETUP_CODE				\
   {						\
      /* texturing must be off */		\
      ASSERT(ctx->Texture._EnabledCoordUnits == 0);	\
      ASSERT(ctx->Light.ShadeModel==GL_SMOOTH);	\
   }
#define RENDER_SPAN( span )  _swrast_write_rgba_span(ctx, &span);
#include "s_tritemp.h"



/*
 * Render an RGB, GL_DECAL, textured triangle.
 * Interpolate S,T only w/out mipmapping or perspective correction.
 *
 * No fog.  No depth testing.
 */
#define NAME simple_textured_triangle
#define INTERP_INT_TEX 1
#define S_SCALE twidth
#define T_SCALE theight

#define SETUP_CODE							\
   struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];	\
   struct gl_texture_object *obj = ctx->Texture.Unit[0].Current2D;	\
   const GLint b = obj->BaseLevel;					\
   const GLfloat twidth = (GLfloat) obj->Image[0][b]->Width;		\
   const GLfloat theight = (GLfloat) obj->Image[0][b]->Height;		\
   const GLint twidth_log2 = obj->Image[0][b]->WidthLog2;		\
   const GLchan *texture = (const GLchan *) obj->Image[0][b]->Data;	\
   const GLint smask = obj->Image[0][b]->Width - 1;			\
   const GLint tmask = obj->Image[0][b]->Height - 1;			\
   if (!rb || !texture) {						\
      return;								\
   }

#define RENDER_SPAN( span )						\
   GLuint i;								\
   GLchan rgb[MAX_WIDTH][3];						\
   span.intTex[0] -= FIXED_HALF; /* off-by-one error? */		\
   span.intTex[1] -= FIXED_HALF;					\
   for (i = 0; i < span.end; i++) {					\
      GLint s = FixedToInt(span.intTex[0]) & smask;			\
      GLint t = FixedToInt(span.intTex[1]) & tmask;			\
      GLint pos = (t << twidth_log2) + s;				\
      pos = pos + pos + pos;  /* multiply by 3 */			\
      rgb[i][RCOMP] = texture[pos];					\
      rgb[i][GCOMP] = texture[pos+1];					\
      rgb[i][BCOMP] = texture[pos+2];					\
      span.intTex[0] += span.intTexStep[0];				\
      span.intTex[1] += span.intTexStep[1];				\
   }									\
   rb->PutRowRGB(ctx, rb, span.end, span.x, span.y, rgb, NULL);

#include "s_tritemp.h"



/*
 * Render an RGB, GL_DECAL, textured triangle.
 * Interpolate S,T, GL_LESS depth test, w/out mipmapping or
 * perspective correction.
 * Depth buffer bits must be <= sizeof(DEFAULT_SOFTWARE_DEPTH_TYPE)
 *
 * No fog.
 */
#define NAME simple_z_textured_triangle
#define INTERP_Z 1
#define DEPTH_TYPE DEFAULT_SOFTWARE_DEPTH_TYPE
#define INTERP_INT_TEX 1
#define S_SCALE twidth
#define T_SCALE theight

#define SETUP_CODE							\
   struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[0];	\
   struct gl_texture_object *obj = ctx->Texture.Unit[0].Current2D;	\
   const GLint b = obj->BaseLevel;					\
   const GLfloat twidth = (GLfloat) obj->Image[0][b]->Width;		\
   const GLfloat theight = (GLfloat) obj->Image[0][b]->Height;		\
   const GLint twidth_log2 = obj->Image[0][b]->WidthLog2;		\
   const GLchan *texture = (const GLchan *) obj->Image[0][b]->Data;	\
   const GLint smask = obj->Image[0][b]->Width - 1;			\
   const GLint tmask = obj->Image[0][b]->Height - 1;			\
   if (!rb || !texture) {						\
      return;								\
   }

#define RENDER_SPAN( span )						\
   GLuint i;				    				\
   GLchan rgb[MAX_WIDTH][3];						\
   span.intTex[0] -= FIXED_HALF; /* off-by-one error? */		\
   span.intTex[1] -= FIXED_HALF;					\
   for (i = 0; i < span.end; i++) {					\
      const GLuint z = FixedToDepth(span.z);				\
      if (z < zRow[i]) {						\
         GLint s = FixedToInt(span.intTex[0]) & smask;			\
         GLint t = FixedToInt(span.intTex[1]) & tmask;			\
         GLint pos = (t << twidth_log2) + s;				\
         pos = pos + pos + pos;  /* multiply by 3 */			\
         rgb[i][RCOMP] = texture[pos];					\
         rgb[i][GCOMP] = texture[pos+1];				\
         rgb[i][BCOMP] = texture[pos+2];				\
         zRow[i] = z;							\
         span.array->mask[i] = 1;					\
      }									\
      else {								\
         span.array->mask[i] = 0;					\
      }									\
      span.intTex[0] += span.intTexStep[0];				\
      span.intTex[1] += span.intTexStep[1];				\
      span.z += span.zStep;						\
   }									\
   rb->PutRowRGB(ctx, rb, span.end, span.x, span.y, rgb, span.array->mask);

#include "s_tritemp.h"


#if CHAN_TYPE != GL_FLOAT

struct affine_info
{
   GLenum filter;
   GLenum format;
   GLenum envmode;
   GLint smask, tmask;
   GLint twidth_log2;
   const GLchan *texture;
   GLfixed er, eg, eb, ea;
   GLint tbytesline, tsize;
};


static INLINE GLint
ilerp(GLint t, GLint a, GLint b)
{
   return a + ((t * (b - a)) >> FIXED_SHIFT);
}

static INLINE GLint
ilerp_2d(GLint ia, GLint ib, GLint v00, GLint v10, GLint v01, GLint v11)
{
   const GLint temp0 = ilerp(ia, v00, v10);
   const GLint temp1 = ilerp(ia, v01, v11);
   return ilerp(ib, temp0, temp1);
}


/* This function can handle GL_NEAREST or GL_LINEAR sampling of 2D RGB or RGBA
 * textures with GL_REPLACE, GL_MODULATE, GL_BLEND, GL_DECAL or GL_ADD
 * texture env modes.
 */
static INLINE void
affine_span(GLcontext *ctx, SWspan *span,
            struct affine_info *info)
{
   GLchan sample[4];  /* the filtered texture sample */

   /* Instead of defining a function for each mode, a test is done
    * between the outer and inner loops. This is to reduce code size
    * and complexity. Observe that an optimizing compiler kills
    * unused variables (for instance tf,sf,ti,si in case of GL_NEAREST).
    */

#define NEAREST_RGB			\
   sample[RCOMP] = tex00[RCOMP];	\
   sample[GCOMP] = tex00[GCOMP];	\
   sample[BCOMP] = tex00[BCOMP];	\
   sample[ACOMP] = CHAN_MAX

#define LINEAR_RGB							\
   sample[RCOMP] = ilerp_2d(sf, tf, tex00[0], tex01[0], tex10[0], tex11[0]);\
   sample[GCOMP] = ilerp_2d(sf, tf, tex00[1], tex01[1], tex10[1], tex11[1]);\
   sample[BCOMP] = ilerp_2d(sf, tf, tex00[2], tex01[2], tex10[2], tex11[2]);\
   sample[ACOMP] = CHAN_MAX;

#define NEAREST_RGBA  COPY_CHAN4(sample, tex00)

#define LINEAR_RGBA							\
   sample[RCOMP] = ilerp_2d(sf, tf, tex00[0], tex01[0], tex10[0], tex11[0]);\
   sample[GCOMP] = ilerp_2d(sf, tf, tex00[1], tex01[1], tex10[1], tex11[1]);\
   sample[BCOMP] = ilerp_2d(sf, tf, tex00[2], tex01[2], tex10[2], tex11[2]);\
   sample[ACOMP] = ilerp_2d(sf, tf, tex00[3], tex01[3], tex10[3], tex11[3])

#define MODULATE							  \
   dest[RCOMP] = span->red   * (sample[RCOMP] + 1u) >> (FIXED_SHIFT + 8); \
   dest[GCOMP] = span->green * (sample[GCOMP] + 1u) >> (FIXED_SHIFT + 8); \
   dest[BCOMP] = span->blue  * (sample[BCOMP] + 1u) >> (FIXED_SHIFT + 8); \
   dest[ACOMP] = span->alpha * (sample[ACOMP] + 1u) >> (FIXED_SHIFT + 8)

#define DECAL								\
   dest[RCOMP] = ((CHAN_MAX - sample[ACOMP]) * span->red +		\
               ((sample[ACOMP] + 1) * sample[RCOMP] << FIXED_SHIFT))	\
               >> (FIXED_SHIFT + 8);					\
   dest[GCOMP] = ((CHAN_MAX - sample[ACOMP]) * span->green +		\
               ((sample[ACOMP] + 1) * sample[GCOMP] << FIXED_SHIFT))	\
               >> (FIXED_SHIFT + 8);					\
   dest[BCOMP] = ((CHAN_MAX - sample[ACOMP]) * span->blue +		\
               ((sample[ACOMP] + 1) * sample[BCOMP] << FIXED_SHIFT))	\
               >> (FIXED_SHIFT + 8);					\
   dest[ACOMP] = FixedToInt(span->alpha)

#define BLEND								\
   dest[RCOMP] = ((CHAN_MAX - sample[RCOMP]) * span->red		\
               + (sample[RCOMP] + 1) * info->er) >> (FIXED_SHIFT + 8);	\
   dest[GCOMP] = ((CHAN_MAX - sample[GCOMP]) * span->green		\
               + (sample[GCOMP] + 1) * info->eg) >> (FIXED_SHIFT + 8);	\
   dest[BCOMP] = ((CHAN_MAX - sample[BCOMP]) * span->blue		\
               + (sample[BCOMP] + 1) * info->eb) >> (FIXED_SHIFT + 8);	\
   dest[ACOMP] = span->alpha * (sample[ACOMP] + 1) >> (FIXED_SHIFT + 8)

#define REPLACE  COPY_CHAN4(dest, sample)

#define ADD								\
   {									\
      GLint rSum = FixedToInt(span->red)   + (GLint) sample[RCOMP];	\
      GLint gSum = FixedToInt(span->green) + (GLint) sample[GCOMP];	\
      GLint bSum = FixedToInt(span->blue)  + (GLint) sample[BCOMP];	\
      dest[RCOMP] = MIN2(rSum, CHAN_MAX);				\
      dest[GCOMP] = MIN2(gSum, CHAN_MAX);				\
      dest[BCOMP] = MIN2(bSum, CHAN_MAX);				\
      dest[ACOMP] = span->alpha * (sample[ACOMP] + 1) >> (FIXED_SHIFT + 8); \
  }

/* shortcuts */

#define NEAREST_RGB_REPLACE		\
   NEAREST_RGB;				\
   dest[0] = sample[0];			\
   dest[1] = sample[1];			\
   dest[2] = sample[2];			\
   dest[3] = FixedToInt(span->alpha);

#define NEAREST_RGBA_REPLACE  COPY_CHAN4(dest, tex00)

#define SPAN_NEAREST(DO_TEX, COMPS)					\
	for (i = 0; i < span->end; i++) {				\
           /* Isn't it necessary to use FixedFloor below?? */		\
           GLint s = FixedToInt(span->intTex[0]) & info->smask;		\
           GLint t = FixedToInt(span->intTex[1]) & info->tmask;		\
           GLint pos = (t << info->twidth_log2) + s;			\
           const GLchan *tex00 = info->texture + COMPS * pos;		\
           DO_TEX;							\
           span->red += span->redStep;					\
	   span->green += span->greenStep;				\
           span->blue += span->blueStep;				\
	   span->alpha += span->alphaStep;				\
	   span->intTex[0] += span->intTexStep[0];			\
	   span->intTex[1] += span->intTexStep[1];			\
           dest += 4;							\
	}

#define SPAN_LINEAR(DO_TEX, COMPS)					\
	for (i = 0; i < span->end; i++) {				\
           /* Isn't it necessary to use FixedFloor below?? */		\
           const GLint s = FixedToInt(span->intTex[0]) & info->smask;	\
           const GLint t = FixedToInt(span->intTex[1]) & info->tmask;	\
           const GLfixed sf = span->intTex[0] & FIXED_FRAC_MASK;	\
           const GLfixed tf = span->intTex[1] & FIXED_FRAC_MASK;	\
           const GLint pos = (t << info->twidth_log2) + s;		\
           const GLchan *tex00 = info->texture + COMPS * pos;		\
           const GLchan *tex10 = tex00 + info->tbytesline;		\
           const GLchan *tex01 = tex00 + COMPS;				\
           const GLchan *tex11 = tex10 + COMPS;				\
           if (t == info->tmask) {					\
              tex10 -= info->tsize;					\
              tex11 -= info->tsize;					\
           }								\
           if (s == info->smask) {					\
              tex01 -= info->tbytesline;				\