src/mesa/swrast/s_aaline.c - platform/external/mesa3d - Gitiles

 /*
  * 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.
  */


 #include "main/glheader.h"
 #include "main/imports.h"
 #include "main/macros.h"
 #include "swrast/s_aaline.h"
 #include "swrast/s_context.h"
 #include "swrast/s_span.h"
 #include "swrast/swrast.h"
 #include "main/mtypes.h"


 #define SUB_PIXEL 4


 /*
  * Info about the AA line we're rendering
  */
 struct LineInfo
 {
    GLfloat x0, y0;        /* start */
    GLfloat x1, y1;        /* end */
    GLfloat dx, dy;        /* direction vector */
    GLfloat len;           /* length */
    GLfloat halfWidth;     /* half of line width */
    GLfloat xAdj, yAdj;    /* X and Y adjustment for quad corners around line */
    /* for coverage computation */
    GLfloat qx0, qy0;      /* quad vertices */
    GLfloat qx1, qy1;
    GLfloat qx2, qy2;
    GLfloat qx3, qy3;
    GLfloat ex0, ey0;      /* quad edge vectors */
    GLfloat ex1, ey1;
    GLfloat ex2, ey2;
    GLfloat ex3, ey3;

    /* DO_Z */
    GLfloat zPlane[4];
    /* DO_RGBA */
    GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
    /* DO_INDEX */
    GLfloat iPlane[4];
    /* DO_ATTRIBS */
    GLfloat wPlane[4];
    GLfloat attrPlane[FRAG_ATTRIB_MAX][4][4];
    GLfloat lambda[FRAG_ATTRIB_MAX];
    GLfloat texWidth[FRAG_ATTRIB_MAX];
    GLfloat texHeight[FRAG_ATTRIB_MAX];

    SWspan span;
 };


 /*
  * Compute the equation of a plane used to interpolate line fragment data
  * such as color, Z, texture coords, etc.
  * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
  *        z0, and z1 are the end point values to interpolate.
  * Output:  plane - the plane equation.
  *
  * Note: we don't really have enough parameters to specify a plane.
  * We take the endpoints of the line and compute a plane such that
  * the cross product of the line vector and the plane normal is
  * parallel to the projection plane.
  */
 static void
 compute_plane(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
               GLfloat z0, GLfloat z1, GLfloat plane[4])
 {
 #if 0
    /* original */
    const GLfloat px = x1 - x0;
    const GLfloat py = y1 - y0;
    const GLfloat pz = z1 - z0;
    const GLfloat qx = -py;
    const GLfloat qy = px;
    const GLfloat qz = 0;
    const GLfloat a = py * qz - pz * qy;
    const GLfloat b = pz * qx - px * qz;
    const GLfloat c = px * qy - py * qx;
    const GLfloat d = -(a * x0 + b * y0 + c * z0);
    plane[0] = a;
    plane[1] = b;
    plane[2] = c;
    plane[3] = d;
 #else
    /* simplified */
    const GLfloat px = x1 - x0;
    const GLfloat py = y1 - y0;
    const GLfloat pz = z0 - z1;
    const GLfloat a = pz * px;
    const GLfloat b = pz * py;
    const GLfloat c = px * px + py * py;
    const GLfloat d = -(a * x0 + b * y0 + c * z0);
    if (a == 0.0 && b == 0.0 && c == 0.0 && d == 0.0) {
       plane[0] = 0.0;
       plane[1] = 0.0;
       plane[2] = 1.0;
       plane[3] = 0.0;
    }
    else {
       plane[0] = a;
       plane[1] = b;
       plane[2] = c;
       plane[3] = d;
    }
 #endif
 }


 static INLINE void
 constant_plane(GLfloat value, GLfloat plane[4])
 {
    plane[0] = 0.0;
    plane[1] = 0.0;
    plane[2] = -1.0;
    plane[3] = value;
 }


 static INLINE GLfloat
 solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
 {
    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
    return z;
 }

 #define SOLVE_PLANE(X, Y, PLANE) \
    ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])


 /*
  * Return 1 / solve_plane().
  */
 static INLINE GLfloat
 solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
 {
    const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
    if (denom == 0.0)
       return 0.0;
    else
       return -plane[2] / denom;
 }


 /*
  * Solve plane and return clamped GLchan value.
  */
 static INLINE GLchan
 solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
 {
    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
 #if CHAN_TYPE == GL_FLOAT
    return CLAMP(z, 0.0F, CHAN_MAXF);
 #else
    if (z < 0)
       return 0;
    else if (z > CHAN_MAX)
       return CHAN_MAX;
    return (GLchan) IROUND_POS(z);
 #endif
 }


 /*
  * Compute mipmap level of detail.
  */
 static INLINE GLfloat
 compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
                GLfloat invQ, GLfloat width, GLfloat height)
 {
    GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
    GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
    GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
    GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
    GLfloat r1 = dudx * dudx + dudy * dudy;
    GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
    GLfloat rho2 = r1 + r2;
    /* return log base 2 of rho */
    if (rho2 == 0.0F)
       return 0.0;
    else
       return (GLfloat) (LOGF(rho2) * 1.442695 * 0.5);/* 1.442695 = 1/log(2) */
 }


 /*
  * Fill in the samples[] array with the (x,y) subpixel positions of
  * xSamples * ySamples sample positions.
  * Note that the four corner samples are put into the first four
  * positions of the array.  This allows us to optimize for the common
  * case of all samples being inside the polygon.
  */
 static void
 make_sample_table(GLint xSamples, GLint ySamples, GLfloat samples[][2])
 {
    const GLfloat dx = 1.0F / (GLfloat) xSamples;
    const GLfloat dy = 1.0F / (GLfloat) ySamples;
    GLint x, y;
    GLint i;

    i = 4;
    for (x = 0; x < xSamples; x++) {
       for (y = 0; y < ySamples; y++) {
          GLint j;
          if (x == 0 && y == 0) {
             /* lower left */
             j = 0;
          }
          else if (x == xSamples - 1 && y == 0) {
             /* lower right */
             j = 1;
          }
          else if (x == 0 && y == ySamples - 1) {
             /* upper left */
             j = 2;
          }
          else if (x == xSamples - 1 && y == ySamples - 1) {
             /* upper right */
             j = 3;
          }
          else {
             j = i++;
          }
          samples[j][0] = x * dx + 0.5F * dx;
          samples[j][1] = y * dy + 0.5F * dy;
       }
    }
 }


 /*
  * Compute how much of the given pixel's area is inside the rectangle
  * defined by vertices v0, v1, v2, v3.
  * Vertices MUST be specified in counter-clockwise order.
  * Return:  coverage in [0, 1].
  */
 static GLfloat
 compute_coveragef(const struct LineInfo *info,
                   GLint winx, GLint winy)
 {
    static GLfloat samples[SUB_PIXEL * SUB_PIXEL][2];
    static GLboolean haveSamples = GL_FALSE;
    const GLfloat x = (GLfloat) winx;
    const GLfloat y = (GLfloat) winy;
    GLint stop = 4, i;
    GLfloat insideCount = SUB_PIXEL * SUB_PIXEL;

    if (!haveSamples) {
       make_sample_table(SUB_PIXEL, SUB_PIXEL, samples);
       haveSamples = GL_TRUE;
    }

 #if 0 /*DEBUG*/
    {
       const GLfloat area = dx0 * dy1 - dx1 * dy0;
       assert(area >= 0.0);
    }
 #endif

    for (i = 0; i < stop; i++) {
       const GLfloat sx = x + samples[i][0];
       const GLfloat sy = y + samples[i][1];
       const GLfloat fx0 = sx - info->qx0;
       const GLfloat fy0 = sy - info->qy0;
       const GLfloat fx1 = sx - info->qx1;
       const GLfloat fy1 = sy - info->qy1;
       const GLfloat fx2 = sx - info->qx2;
       const GLfloat fy2 = sy - info->qy2;
       const GLfloat fx3 = sx - info->qx3;
       const GLfloat fy3 = sy - info->qy3;
       /* cross product determines if sample is inside or outside each edge */
       GLfloat cross0 = (info->ex0 * fy0 - info->ey0 * fx0);
       GLfloat cross1 = (info->ex1 * fy1 - info->ey1 * fx1);
       GLfloat cross2 = (info->ex2 * fy2 - info->ey2 * fx2);
       GLfloat cross3 = (info->ex3 * fy3 - info->ey3 * fx3);
       /* Check if the sample is exactly on an edge.  If so, let cross be a
        * positive or negative value depending on the direction of the edge.
        */
       if (cross0 == 0.0F)
          cross0 = info->ex0 + info->ey0;
       if (cross1 == 0.0F)
          cross1 = info->ex1 + info->ey1;
       if (cross2 == 0.0F)
          cross2 = info->ex2 + info->ey2;
       if (cross3 == 0.0F)
          cross3 = info->ex3 + info->ey3;
       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F || cross3 < 0.0F) {
          /* point is outside quadrilateral */
          insideCount -= 1.0F;
          stop = SUB_PIXEL * SUB_PIXEL;
       }
    }
    if (stop == 4)
       return 1.0F;
    else
       return insideCount * (1.0F / (SUB_PIXEL * SUB_PIXEL));
 }


 /**
  * Compute coverage value for color index mode.
  * XXX this may not be quite correct.
  * \return coverage in [0,15].
  */
 static GLfloat
 compute_coveragei(const struct LineInfo *info,
                   GLint winx, GLint winy)
 {
    return compute_coveragef(info, winx, winy) * 15.0F;
 }


 typedef void (*plot_func)(GLcontext *ctx, struct LineInfo *line,
                           int ix, int iy);


 /*
  * Draw an AA line segment (called many times per line when stippling)
  */
 static void
 segment(GLcontext *ctx,
         struct LineInfo *line,
         plot_func plot,
         GLfloat t0, GLfloat t1)
 {
    const GLfloat absDx = (line->dx < 0.0F) ? -line->dx : line->dx;
    const GLfloat absDy = (line->dy < 0.0F) ? -line->dy : line->dy;
    /* compute the actual segment's endpoints */
    const GLfloat x0 = line->x0 + t0 * line->dx;
    const GLfloat y0 = line->y0 + t0 * line->dy;
    const GLfloat x1 = line->x0 + t1 * line->dx;
    const GLfloat y1 = line->y0 + t1 * line->dy;

    /* compute vertices of the line-aligned quadrilateral */
    line->qx0 = x0 - line->yAdj;
    line->qy0 = y0 + line->xAdj;
    line->qx1 = x0 + line->yAdj;
    line->qy1 = y0 - line->xAdj;
    line->qx2 = x1 + line->yAdj;
    line->qy2 = y1 - line->xAdj;
    line->qx3 = x1 - line->yAdj;
    line->qy3 = y1 + line->xAdj;
    /* compute the quad's edge vectors (for coverage calc) */
    line->ex0 = line->qx1 - line->qx0;
    line->ey0 = line->qy1 - line->qy0;
    line->ex1 = line->qx2 - line->qx1;
    line->ey1 = line->qy2 - line->qy1;
    line->ex2 = line->qx3 - line->qx2;
    line->ey2 = line->qy3 - line->qy2;
    line->ex3 = line->qx0 - line->qx3;
    line->ey3 = line->qy0 - line->qy3;

    if (absDx > absDy) {
       /* X-major line */
       GLfloat dydx = line->dy / line->dx;
       GLfloat xLeft, xRight, yBot, yTop;
       GLint ix, ixRight;
       if (x0 < x1) {
          xLeft = x0 - line->halfWidth;
          xRight = x1 + line->halfWidth;
          if (line->dy >= 0.0) {
             yBot = y0 - 3.0F * line->halfWidth;
             yTop = y0 + line->halfWidth;
          }
          else {
             yBot = y0 - line->halfWidth;
             yTop = y0 + 3.0F * line->halfWidth;
          }
       }
       else {
          xLeft = x1 - line->halfWidth;
          xRight = x0 + line->halfWidth;
          if (line->dy <= 0.0) {
             yBot = y1 - 3.0F * line->halfWidth;
             yTop = y1 + line->halfWidth;
          }
          else {
             yBot = y1 - line->halfWidth;
             yTop = y1 + 3.0F * line->halfWidth;
          }
       }

       /* scan along the line, left-to-right */
       ixRight = (GLint) (xRight + 1.0F);

       /*printf("avg span height: %g\n", yTop - yBot);*/
       for (ix = (GLint) xLeft; ix < ixRight; ix++) {
          const GLint iyBot = (GLint) yBot;
          const GLint iyTop = (GLint) (yTop + 1.0F);
          GLint iy;
          /* scan across the line, bottom-to-top */
          for (iy = iyBot; iy < iyTop; iy++) {
             (*plot)(ctx, line, ix, iy);
          }
          yBot += dydx;
          yTop += dydx;
       }
    }
    else {
       /* Y-major line */
       GLfloat dxdy = line->dx / line->dy;
       GLfloat yBot, yTop, xLeft, xRight;
       GLint iy, iyTop;
       if (y0 < y1) {
          yBot = y0 - line->halfWidth;
          yTop = y1 + line->halfWidth;
          if (line->dx >= 0.0) {
             xLeft = x0 - 3.0F * line->halfWidth;
             xRight = x0 + line->halfWidth;
          }
          else {
             xLeft = x0 - line->halfWidth;
             xRight = x0 + 3.0F * line->halfWidth;
          }
       }
       else {
          yBot = y1 - line->halfWidth;
          yTop = y0 + line->halfWidth;
          if (line->dx <= 0.0) {
             xLeft = x1 - 3.0F * line->halfWidth;
             xRight = x1 + line->halfWidth;
          }
          else {
             xLeft = x1 - line->halfWidth;
             xRight = x1 + 3.0F * line->halfWidth;
          }
       }

       /* scan along the line, bottom-to-top */
       iyTop = (GLint) (yTop + 1.0F);

       /*printf("avg span width: %g\n", xRight - xLeft);*/
       for (iy = (GLint) yBot; iy < iyTop; iy++) {
          const GLint ixLeft = (GLint) xLeft;
          const GLint ixRight = (GLint) (xRight + 1.0F);
          GLint ix;
          /* scan across the line, left-to-right */
          for (ix = ixLeft; ix < ixRight; ix++) {
             (*plot)(ctx, line, ix, iy);
          }
          xLeft += dxdy;
          xRight += dxdy;
       }
    }
 }


 #define NAME(x) aa_ci_##x
 #define DO_Z
 #define DO_ATTRIBS /* for fog */
 #define DO_INDEX
 #include "s_aalinetemp.h"


 #define NAME(x) aa_rgba_##x
 #define DO_Z
 #define DO_RGBA
 #include "s_aalinetemp.h"


 #define NAME(x)  aa_general_rgba_##x
 #define DO_Z
 #define DO_RGBA
 #define DO_ATTRIBS
 #include "s_aalinetemp.h"


 void
 _swrast_choose_aa_line_function(GLcontext *ctx)
 {
    SWcontext *swrast = SWRAST_CONTEXT(ctx);

    ASSERT(ctx->Line.SmoothFlag);

    if (ctx->Visual.rgbMode) {
       /* RGBA */
       if (ctx->Texture._EnabledCoordUnits != 0
           || ctx->FragmentProgram._Current
           || (ctx->Light.Enabled &&
               ctx->Light.Model.ColorControl == GL_SEPARATE_SPECULAR_COLOR)
           || ctx->Fog.ColorSumEnabled
           || swrast->_FogEnabled) {
          swrast->Line = aa_general_rgba_line;
       }
       else {
          swrast->Line = aa_rgba_line;
       }
    }
    else {
       /* Color Index */
       swrast->Line = aa_ci_line;
    }
 }
	/*
	* 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.
	*/


	#include "main/glheader.h"
	#include "main/imports.h"
	#include "main/macros.h"
	#include "swrast/s_aaline.h"
	#include "swrast/s_context.h"
	#include "swrast/s_span.h"
	#include "swrast/swrast.h"
	#include "main/mtypes.h"


	#define SUB_PIXEL 4


	/*
	* Info about the AA line we're rendering
	*/
	struct LineInfo
	{
	GLfloat x0, y0; /* start */
	GLfloat x1, y1; /* end */
	GLfloat dx, dy; /* direction vector */
	GLfloat len; /* length */
	GLfloat halfWidth; /* half of line width */
	GLfloat xAdj, yAdj; /* X and Y adjustment for quad corners around line */
	/* for coverage computation */
	GLfloat qx0, qy0; /* quad vertices */
	GLfloat qx1, qy1;
	GLfloat qx2, qy2;
	GLfloat qx3, qy3;
	GLfloat ex0, ey0; /* quad edge vectors */
	GLfloat ex1, ey1;
	GLfloat ex2, ey2;
	GLfloat ex3, ey3;

	/* DO_Z */
	GLfloat zPlane[4];
	/* DO_RGBA */
	GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
	/* DO_INDEX */
	GLfloat iPlane[4];
	/* DO_ATTRIBS */
	GLfloat wPlane[4];
	GLfloat attrPlane[FRAG_ATTRIB_MAX][4][4];
	GLfloat lambda[FRAG_ATTRIB_MAX];
	GLfloat texWidth[FRAG_ATTRIB_MAX];
	GLfloat texHeight[FRAG_ATTRIB_MAX];

	SWspan span;
	};



	/*
	* Compute the equation of a plane used to interpolate line fragment data
	* such as color, Z, texture coords, etc.
	* Input: (x0, y0) and (x1,y1) are the endpoints of the line.
	* z0, and z1 are the end point values to interpolate.
	* Output: plane - the plane equation.
	*
	* Note: we don't really have enough parameters to specify a plane.
	* We take the endpoints of the line and compute a plane such that
	* the cross product of the line vector and the plane normal is
	* parallel to the projection plane.
	*/
	static void
	compute_plane(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
	GLfloat z0, GLfloat z1, GLfloat plane[4])
	{
	#if 0
	/* original */
	const GLfloat px = x1 - x0;
	const GLfloat py = y1 - y0;
	const GLfloat pz = z1 - z0;
	const GLfloat qx = -py;
	const GLfloat qy = px;
	const GLfloat qz = 0;
	const GLfloat a = py * qz - pz * qy;
	const GLfloat b = pz * qx - px * qz;
	const GLfloat c = px * qy - py * qx;
	const GLfloat d = -(a * x0 + b * y0 + c * z0);
	plane[0] = a;
	plane[1] = b;
	plane[2] = c;
	plane[3] = d;
	#else
	/* simplified */
	const GLfloat px = x1 - x0;
	const GLfloat py = y1 - y0;
	const GLfloat pz = z0 - z1;
	const GLfloat a = pz * px;
	const GLfloat b = pz * py;
	const GLfloat c = px * px + py * py;
	const GLfloat d = -(a * x0 + b * y0 + c * z0);
	if (a == 0.0 && b == 0.0 && c == 0.0 && d == 0.0) {
	plane[0] = 0.0;
	plane[1] = 0.0;
	plane[2] = 1.0;
	plane[3] = 0.0;
	}
	else {
	plane[0] = a;
	plane[1] = b;
	plane[2] = c;
	plane[3] = d;
	}
	#endif
	}


	static INLINE void
	constant_plane(GLfloat value, GLfloat plane[4])
	{
	plane[0] = 0.0;
	plane[1] = 0.0;
	plane[2] = -1.0;
	plane[3] = value;
	}


	static INLINE GLfloat
	solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
	{
	const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
	return z;
	}

	#define SOLVE_PLANE(X, Y, PLANE) \
	((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])


	/*
	* Return 1 / solve_plane().
	*/
	static INLINE GLfloat
	solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
	{
	const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
	if (denom == 0.0)
	return 0.0;
	else
	return -plane[2] / denom;
	}


	/*
	* Solve plane and return clamped GLchan value.
	*/
	static INLINE GLchan
	solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
	{
	const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
	#if CHAN_TYPE == GL_FLOAT
	return CLAMP(z, 0.0F, CHAN_MAXF);
	#else
	if (z < 0)
	return 0;
	else if (z > CHAN_MAX)
	return CHAN_MAX;
	return (GLchan) IROUND_POS(z);
	#endif
	}


	/*
	* Compute mipmap level of detail.
	*/
	static INLINE GLfloat
	compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
	GLfloat invQ, GLfloat width, GLfloat height)
	{
	GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
	GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
	GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
	GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
	GLfloat r1 = dudx * dudx + dudy * dudy;
	GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
	GLfloat rho2 = r1 + r2;
	/* return log base 2 of rho */
	if (rho2 == 0.0F)
	return 0.0;
	else
	return (GLfloat) (LOGF(rho2) * 1.442695 * 0.5);/* 1.442695 = 1/log(2) */
	}




	/*
	* Fill in the samples[] array with the (x,y) subpixel positions of
	* xSamples * ySamples sample positions.
	* Note that the four corner samples are put into the first four
	* positions of the array. This allows us to optimize for the common
	* case of all samples being inside the polygon.
	*/
	static void
	make_sample_table(GLint xSamples, GLint ySamples, GLfloat samples[][2])
	{
	const GLfloat dx = 1.0F / (GLfloat) xSamples;
	const GLfloat dy = 1.0F / (GLfloat) ySamples;
	GLint x, y;
	GLint i;

	i = 4;
	for (x = 0; x < xSamples; x++) {
	for (y = 0; y < ySamples; y++) {
	GLint j;
	if (x == 0 && y == 0) {
	/* lower left */
	j = 0;
	}
	else if (x == xSamples - 1 && y == 0) {
	/* lower right */
	j = 1;
	}
	else if (x == 0 && y == ySamples - 1) {
	/* upper left */
	j = 2;
	}
	else if (x == xSamples - 1 && y == ySamples - 1) {
	/* upper right */
	j = 3;
	}
	else {
	j = i++;
	}
	samples[j][0] = x * dx + 0.5F * dx;
	samples[j][1] = y * dy + 0.5F * dy;
	}
	}
	}



	/*
	* Compute how much of the given pixel's area is inside the rectangle
	* defined by vertices v0, v1, v2, v3.
	* Vertices MUST be specified in counter-clockwise order.
	* Return: coverage in [0, 1].
	*/
	static GLfloat
	compute_coveragef(const struct LineInfo *info,
	GLint winx, GLint winy)
	{
	static GLfloat samples[SUB_PIXEL * SUB_PIXEL][2];
	static GLboolean haveSamples = GL_FALSE;
	const GLfloat x = (GLfloat) winx;
	const GLfloat y = (GLfloat) winy;
	GLint stop = 4, i;
	GLfloat insideCount = SUB_PIXEL * SUB_PIXEL;

	if (!haveSamples) {
	make_sample_table(SUB_PIXEL, SUB_PIXEL, samples);
	haveSamples = GL_TRUE;
	}

	#if 0 /DEBUG/
	{
	const GLfloat area = dx0 * dy1 - dx1 * dy0;
	assert(area >= 0.0);
	}
	#endif

	for (i = 0; i < stop; i++) {
	const GLfloat sx = x + samples[i][0];
	const GLfloat sy = y + samples[i][1];
	const GLfloat fx0 = sx - info->qx0;
	const GLfloat fy0 = sy - info->qy0;
	const GLfloat fx1 = sx - info->qx1;
	const GLfloat fy1 = sy - info->qy1;
	const GLfloat fx2 = sx - info->qx2;
	const GLfloat fy2 = sy - info->qy2;
	const GLfloat fx3 = sx - info->qx3;
	const GLfloat fy3 = sy - info->qy3;
	/* cross product determines if sample is inside or outside each edge */
	GLfloat cross0 = (info->ex0 * fy0 - info->ey0 * fx0);
	GLfloat cross1 = (info->ex1 * fy1 - info->ey1 * fx1);
	GLfloat cross2 = (info->ex2 * fy2 - info->ey2 * fx2);
	GLfloat cross3 = (info->ex3 * fy3 - info->ey3 * fx3);
	/* Check if the sample is exactly on an edge. If so, let cross be a
	* positive or negative value depending on the direction of the edge.
	*/
	if (cross0 == 0.0F)
	cross0 = info->ex0 + info->ey0;
	if (cross1 == 0.0F)
	cross1 = info->ex1 + info->ey1;
	if (cross2 == 0.0F)
	cross2 = info->ex2 + info->ey2;
	if (cross3 == 0.0F)
	cross3 = info->ex3 + info->ey3;
	if (cross0 < 0.0F \|\| cross1 < 0.0F \|\| cross2 < 0.0F \|\| cross3 < 0.0F) {
	/* point is outside quadrilateral */
	insideCount -= 1.0F;
	stop = SUB_PIXEL * SUB_PIXEL;
	}
	}
	if (stop == 4)
	return 1.0F;
	else
	return insideCount * (1.0F / (SUB_PIXEL * SUB_PIXEL));
	}


	/**
	* Compute coverage value for color index mode.
	* XXX this may not be quite correct.
	* \return coverage in [0,15].
	*/
	static GLfloat
	compute_coveragei(const struct LineInfo *info,
	GLint winx, GLint winy)
	{
	return compute_coveragef(info, winx, winy) * 15.0F;
	}



	typedef void (plot_func)(GLcontext ctx, struct LineInfo *line,
	int ix, int iy);



	/*
	* Draw an AA line segment (called many times per line when stippling)
	*/
	static void
	segment(GLcontext *ctx,
	struct LineInfo *line,
	plot_func plot,
	GLfloat t0, GLfloat t1)
	{
	const GLfloat absDx = (line->dx < 0.0F) ? -line->dx : line->dx;
	const GLfloat absDy = (line->dy < 0.0F) ? -line->dy : line->dy;
	/* compute the actual segment's endpoints */
	const GLfloat x0 = line->x0 + t0 * line->dx;
	const GLfloat y0 = line->y0 + t0 * line->dy;
	const GLfloat x1 = line->x0 + t1 * line->dx;
	const GLfloat y1 = line->y0 + t1 * line->dy;

	/* compute vertices of the line-aligned quadrilateral */
	line->qx0 = x0 - line->yAdj;
	line->qy0 = y0 + line->xAdj;
	line->qx1 = x0 + line->yAdj;
	line->qy1 = y0 - line->xAdj;
	line->qx2 = x1 + line->yAdj;
	line->qy2 = y1 - line->xAdj;
	line->qx3 = x1 - line->yAdj;
	line->qy3 = y1 + line->xAdj;
	/* compute the quad's edge vectors (for coverage calc) */
	line->ex0 = line->qx1 - line->qx0;
	line->ey0 = line->qy1 - line->qy0;
	line->ex1 = line->qx2 - line->qx1;
	line->ey1 = line->qy2 - line->qy1;
	line->ex2 = line->qx3 - line->qx2;
	line->ey2 = line->qy3 - line->qy2;
	line->ex3 = line->qx0 - line->qx3;
	line->ey3 = line->qy0 - line->qy3;

	if (absDx > absDy) {
	/* X-major line */
	GLfloat dydx = line->dy / line->dx;
	GLfloat xLeft, xRight, yBot, yTop;
	GLint ix, ixRight;
	if (x0 < x1) {
	xLeft = x0 - line->halfWidth;
	xRight = x1 + line->halfWidth;
	if (line->dy >= 0.0) {
	yBot = y0 - 3.0F * line->halfWidth;
	yTop = y0 + line->halfWidth;
	}
	else {
	yBot = y0 - line->halfWidth;
	yTop = y0 + 3.0F * line->halfWidth;
	}
	}
	else {
	xLeft = x1 - line->halfWidth;
	xRight = x0 + line->halfWidth;
	if (line->dy <= 0.0) {
	yBot = y1 - 3.0F * line->halfWidth;
	yTop = y1 + line->halfWidth;
	}
	else {
	yBot = y1 - line->halfWidth;
	yTop = y1 + 3.0F * line->halfWidth;
	}
	}

	/* scan along the line, left-to-right */
	ixRight = (GLint) (xRight + 1.0F);

	/printf("avg span height: %g\n", yTop - yBot);/
	for (ix = (GLint) xLeft; ix < ixRight; ix++) {
	const GLint iyBot = (GLint) yBot;
	const GLint iyTop = (GLint) (yTop + 1.0F);
	GLint iy;
	/* scan across the line, bottom-to-top */
	for (iy = iyBot; iy < iyTop; iy++) {
	(*plot)(ctx, line, ix, iy);
	}
	yBot += dydx;
	yTop += dydx;
	}
	}
	else {
	/* Y-major line */
	GLfloat dxdy = line->dx / line->dy;
	GLfloat yBot, yTop, xLeft, xRight;
	GLint iy, iyTop;
	if (y0 < y1) {
	yBot = y0 - line->halfWidth;
	yTop = y1 + line->halfWidth;
	if (line->dx >= 0.0) {
	xLeft = x0 - 3.0F * line->halfWidth;
	xRight = x0 + line->halfWidth;
	}
	else {
	xLeft = x0 - line->halfWidth;
	xRight = x0 + 3.0F * line->halfWidth;
	}
	}
	else {
	yBot = y1 - line->halfWidth;
	yTop = y0 + line->halfWidth;
	if (line->dx <= 0.0) {
	xLeft = x1 - 3.0F * line->halfWidth;
	xRight = x1 + line->halfWidth;
	}
	else {
	xLeft = x1 - line->halfWidth;
	xRight = x1 + 3.0F * line->halfWidth;
	}
	}

	/* scan along the line, bottom-to-top */
	iyTop = (GLint) (yTop + 1.0F);

	/printf("avg span width: %g\n", xRight - xLeft);/
	for (iy = (GLint) yBot; iy < iyTop; iy++) {
	const GLint ixLeft = (GLint) xLeft;
	const GLint ixRight = (GLint) (xRight + 1.0F);
	GLint ix;
	/* scan across the line, left-to-right */
	for (ix = ixLeft; ix < ixRight; ix++) {
	(*plot)(ctx, line, ix, iy);
	}
	xLeft += dxdy;
	xRight += dxdy;
	}
	}
	}


	#define NAME(x) aa_ci_##x
	#define DO_Z
	#define DO_ATTRIBS /* for fog */
	#define DO_INDEX
	#include "s_aalinetemp.h"


	#define NAME(x) aa_rgba_##x
	#define DO_Z
	#define DO_RGBA
	#include "s_aalinetemp.h"


	#define NAME(x) aa_general_rgba_##x
	#define DO_Z
	#define DO_RGBA
	#define DO_ATTRIBS
	#include "s_aalinetemp.h"



	void
	_swrast_choose_aa_line_function(GLcontext *ctx)
	{
	SWcontext *swrast = SWRAST_CONTEXT(ctx);

	ASSERT(ctx->Line.SmoothFlag);

	if (ctx->Visual.rgbMode) {
	/* RGBA */
	if (ctx->Texture._EnabledCoordUnits != 0
	\|\| ctx->FragmentProgram._Current
	\|\| (ctx->Light.Enabled &&
	ctx->Light.Model.ColorControl == GL_SEPARATE_SPECULAR_COLOR)
	\|\| ctx->Fog.ColorSumEnabled
	\|\| swrast->_FogEnabled) {
	swrast->Line = aa_general_rgba_line;
	}
	else {
	swrast->Line = aa_rgba_line;
	}
	}
	else {
	/* Color Index */
	swrast->Line = aa_ci_line;
	}
	}