s_span.c

这是一个开放源代码的与WINNT/WIN2K/WIN2003兼容的操作系统

/*
 * Mesa 3-D graphics library
 * Version:  6.3
 *
 * Copyright (C) 1999-2005  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.
 */


/**
 * \file swrast/s_span.c
 * \brief Span processing functions used by all rasterization functions.
 * This is where all the per-fragment tests are performed
 * \author Brian Paul
 */

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

#include "s_atifragshader.h"
#include "s_alpha.h"
#include "s_blend.h"
#include "s_context.h"
#include "s_depth.h"
#include "s_fog.h"
#include "s_logic.h"
#include "s_masking.h"
#include "s_nvfragprog.h"
#include "s_span.h"
#include "s_stencil.h"
#include "s_texture.h"


/**
 * Init span's Z interpolation values to the RasterPos Z.
 * Used during setup for glDraw/CopyPixels.
 */
void
_swrast_span_default_z( GLcontext *ctx, struct sw_span *span )
{
   const GLfloat depthMax = ctx->DrawBuffer->_DepthMaxF;
   if (ctx->Visual.depthBits <= 16)
      span->z = FloatToFixed(ctx->Current.RasterPos[2] * depthMax + 0.5F);
   else
      span->z = (GLint) (ctx->Current.RasterPos[2] * depthMax + 0.5F);
   span->zStep = 0;
   span->interpMask |= SPAN_Z;
}


/**
 * Init span's fog interpolation values to the RasterPos fog.
 * Used during setup for glDraw/CopyPixels.
 */
void
_swrast_span_default_fog( GLcontext *ctx, struct sw_span *span )
{
   span->fog = _swrast_z_to_fogfactor(ctx, ctx->Current.RasterDistance);
   span->fogStep = span->dfogdx = span->dfogdy = 0.0F;
   span->interpMask |= SPAN_FOG;
}


/**
 * Init span's rgba or index interpolation values to the RasterPos color.
 * Used during setup for glDraw/CopyPixels.
 */
void
_swrast_span_default_color( GLcontext *ctx, struct sw_span *span )
{
   if (ctx->Visual.rgbMode) {
      GLchan r, g, b, a;
      UNCLAMPED_FLOAT_TO_CHAN(r, ctx->Current.RasterColor[0]);
      UNCLAMPED_FLOAT_TO_CHAN(g, ctx->Current.RasterColor[1]);
      UNCLAMPED_FLOAT_TO_CHAN(b, ctx->Current.RasterColor[2]);
      UNCLAMPED_FLOAT_TO_CHAN(a, ctx->Current.RasterColor[3]);
#if CHAN_TYPE == GL_FLOAT
      span->red = r;
      span->green = g;
      span->blue = b;
      span->alpha = a;
#else
      span->red   = IntToFixed(r);
      span->green = IntToFixed(g);
      span->blue  = IntToFixed(b);
      span->alpha = IntToFixed(a);
#endif
      span->redStep = 0;
      span->greenStep = 0;
      span->blueStep = 0;
      span->alphaStep = 0;
      span->interpMask |= SPAN_RGBA;
   }
   else {
      span->index = FloatToFixed(ctx->Current.RasterIndex);
      span->indexStep = 0;
      span->interpMask |= SPAN_INDEX;
   }
}


/**
 * Init span's texcoord interpolation values to the RasterPos texcoords.
 * Used during setup for glDraw/CopyPixels.
 */
void
_swrast_span_default_texcoords( GLcontext *ctx, struct sw_span *span )
{
   GLuint i;
   for (i = 0; i < ctx->Const.MaxTextureUnits; i++) {
      const GLfloat *tc = ctx->Current.RasterTexCoords[i];
      if (ctx->FragmentProgram._Active || ctx->ATIFragmentShader._Enabled) {
         COPY_4V(span->tex[i], tc);
      }
      else if (tc[3] > 0.0F) {
         /* use (s/q, t/q, r/q, 1) */
         span->tex[i][0] = tc[0] / tc[3];
         span->tex[i][1] = tc[1] / tc[3];
         span->tex[i][2] = tc[2] / tc[3];
         span->tex[i][3] = 1.0;
      }
      else {
         ASSIGN_4V(span->tex[i], 0.0F, 0.0F, 0.0F, 1.0F);
      }
      ASSIGN_4V(span->texStepX[i], 0.0F, 0.0F, 0.0F, 0.0F);
      ASSIGN_4V(span->texStepY[i], 0.0F, 0.0F, 0.0F, 0.0F);
   }
   span->interpMask |= SPAN_TEXTURE;
}


/* Fill in the span.color.rgba array from the interpolation values */
static void
interpolate_colors(GLcontext *ctx, struct sw_span *span)
{
   const GLuint n = span->end;
   GLchan (*rgba)[4] = span->array->rgba;
   GLuint i;
   (void) ctx;

   ASSERT((span->interpMask & SPAN_RGBA)  &&
	  !(span->arrayMask & SPAN_RGBA));

   if (span->interpMask & SPAN_FLAT) {
      /* constant color */
      GLchan color[4];
      color[RCOMP] = FixedToChan(span->red);
      color[GCOMP] = FixedToChan(span->green);
      color[BCOMP] = FixedToChan(span->blue);
      color[ACOMP] = FixedToChan(span->alpha);
      for (i = 0; i < n; i++) {
         COPY_CHAN4(span->array->rgba[i], color);
      }
   }
   else {
      /* interpolate */
#if CHAN_TYPE == GL_FLOAT
      GLfloat r = span->red;
      GLfloat g = span->green;
      GLfloat b = span->blue;
      GLfloat a = span->alpha;
      const GLfloat dr = span->redStep;
      const GLfloat dg = span->greenStep;
      const GLfloat db = span->blueStep;
      const GLfloat da = span->alphaStep;
#else
      GLfixed r = span->red;
      GLfixed g = span->green;
      GLfixed b = span->blue;
      GLfixed a = span->alpha;
      const GLint dr = span->redStep;
      const GLint dg = span->greenStep;
      const GLint db = span->blueStep;
      const GLint da = span->alphaStep;
#endif
      for (i = 0; i < n; i++) {
         rgba[i][RCOMP] = FixedToChan(r);
         rgba[i][GCOMP] = FixedToChan(g);
         rgba[i][BCOMP] = FixedToChan(b);
         rgba[i][ACOMP] = FixedToChan(a);
         r += dr;
         g += dg;
         b += db;
         a += da;
      }
   }
   span->arrayMask |= SPAN_RGBA;
}


/* Fill in the span.color.index array from the interpolation values */
static void
interpolate_indexes(GLcontext *ctx, struct sw_span *span)
{
   GLfixed index = span->index;
   const GLint indexStep = span->indexStep;
   const GLuint n = span->end;
   GLuint *indexes = span->array->index;
   GLuint i;
   (void) ctx;
   ASSERT((span->interpMask & SPAN_INDEX)  &&
	  !(span->arrayMask & SPAN_INDEX));

   if ((span->interpMask & SPAN_FLAT) || (indexStep == 0)) {
      /* constant color */
      index = FixedToInt(index);
      for (i = 0; i < n; i++) {
         indexes[i] = index;
      }
   }
   else {
      /* interpolate */
      for (i = 0; i < n; i++) {
         indexes[i] = FixedToInt(index);
         index += indexStep;
      }
   }
   span->arrayMask |= SPAN_INDEX;
   span->interpMask &= ~SPAN_INDEX;
}


/* Fill in the span.->array->spec array from the interpolation values */
static void
interpolate_specular(GLcontext *ctx, struct sw_span *span)
{
   (void) ctx;
   if (span->interpMask & SPAN_FLAT) {
      /* constant color */
      const GLchan r = FixedToChan(span->specRed);
      const GLchan g = FixedToChan(span->specGreen);
      const GLchan b = FixedToChan(span->specBlue);
      GLuint i;
      for (i = 0; i < span->end; i++) {
         span->array->spec[i][RCOMP] = r;
         span->array->spec[i][GCOMP] = g;
         span->array->spec[i][BCOMP] = b;
      }
   }
   else {
      /* interpolate */
#if CHAN_TYPE == GL_FLOAT
      GLfloat r = span->specRed;
      GLfloat g = span->specGreen;
      GLfloat b = span->specBlue;
#else
      GLfixed r = span->specRed;
      GLfixed g = span->specGreen;
      GLfixed b = span->specBlue;
#endif
      GLuint i;
      for (i = 0; i < span->end; i++) {
         span->array->spec[i][RCOMP] = FixedToChan(r);
         span->array->spec[i][GCOMP] = FixedToChan(g);
         span->array->spec[i][BCOMP] = FixedToChan(b);
         r += span->specRedStep;
         g += span->specGreenStep;
         b += span->specBlueStep;
      }
   }
   span->arrayMask |= SPAN_SPEC;
}


/* Fill in the span.array.fog values from the interpolation values */
static void
interpolate_fog(const GLcontext *ctx, struct sw_span *span)
{
   GLfloat *fog = span->array->fog;
   const GLfloat fogStep = span->fogStep;
   GLfloat fogCoord = span->fog;
   const GLuint haveW = (span->interpMask & SPAN_W);
   const GLfloat wStep = haveW ? span->dwdx : 0.0F;
   GLfloat w = haveW ? span->w : 1.0F;
   GLuint i;
   for (i = 0; i < span->end; i++) {
      fog[i] = fogCoord / w;
      fogCoord += fogStep;
      w += wStep;
   }
   span->arrayMask |= SPAN_FOG;
}


/* Fill in the span.zArray array from the interpolation values */
void
_swrast_span_interpolate_z( const GLcontext *ctx, struct sw_span *span )
{
   const GLuint n = span->end;
   GLuint i;

   ASSERT((span->interpMask & SPAN_Z)  &&
	  !(span->arrayMask & SPAN_Z));

   if (ctx->Visual.depthBits <= 16) {
      GLfixed zval = span->z;
      GLdepth *z = span->array->z; 
      for (i = 0; i < n; i++) {
         z[i] = FixedToInt(zval);
         zval += span->zStep;
      }
   }
   else {
      /* Deep Z buffer, no fixed->int shift */
      GLfixed zval = span->z;
      GLdepth *z = span->array->z;
      for (i = 0; i < n; i++) {
         z[i] = zval;
         zval += span->zStep;
      }
   }
   span->interpMask &= ~SPAN_Z;
   span->arrayMask |= SPAN_Z;
}


/*
 * This the ideal solution, as given in the OpenGL spec.
 */
#if 0
static GLfloat
compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
               GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,
               GLfloat s, GLfloat t, GLfloat q, GLfloat invQ)
{
   GLfloat dudx = texW * ((s + dsdx) / (q + dqdx) - s * invQ);
   GLfloat dvdx = texH * ((t + dtdx) / (q + dqdx) - t * invQ);
   GLfloat dudy = texW * ((s + dsdy) / (q + dqdy) - s * invQ);
   GLfloat dvdy = texH * ((t + dtdy) / (q + dqdy) - t * invQ);
   GLfloat x = SQRTF(dudx * dudx + dvdx * dvdx);
   GLfloat y = SQRTF(dudy * dudy + dvdy * dvdy);
   GLfloat rho = MAX2(x, y);
   GLfloat lambda = LOG2(rho);
   return lambda;
}
#endif


/*
 * This is a faster approximation
 */
GLfloat
_swrast_compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
                     GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,
                     GLfloat s, GLfloat t, GLfloat q, GLfloat invQ)
{
   GLfloat dsdx2 = (s + dsdx) / (q + dqdx) - s * invQ;
   GLfloat dtdx2 = (t + dtdx) / (q + dqdx) - t * invQ;
   GLfloat dsdy2 = (s + dsdy) / (q + dqdy) - s * invQ;
   GLfloat dtdy2 = (t + dtdy) / (q + dqdy) - t * invQ;
   GLfloat maxU, maxV, rho, lambda;
   dsdx2 = FABSF(dsdx2);
   dsdy2 = FABSF(dsdy2);
   dtdx2 = FABSF(dtdx2);
   dtdy2 = FABSF(dtdy2);
   maxU = MAX2(dsdx2, dsdy2) * texW;
   maxV = MAX2(dtdx2, dtdy2) * texH;
   rho = MAX2(maxU, maxV);
   lambda = LOG2(rho);