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/* $Id: s_aaline.c,v 1.2 2003-04-24 14:22:20 giacomo Exp $ */

/*

 * Mesa 3-D graphics library

 * Version:  4.1

 *

 * Copyright (C) 1999-2002  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 "glheader.h"

#include "swrast/s_aaline.h"

#include "swrast/s_context.h"

#include "swrast/s_span.h"

#include "swrast/swrast.h"

#include "mtypes.h"

#include "mmath.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_FOG */

   GLfloat fPlane[4];

   /* DO_RGBA */

   GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];

   /* DO_INDEX */

   GLfloat iPlane[4];

   /* DO_SPEC */

   GLfloat srPlane[4], sgPlane[4], sbPlane[4];

   /* DO_TEX or DO_MULTITEX */

   GLfloat sPlane[MAX_TEXTURE_UNITS][4];

   GLfloat tPlane[MAX_TEXTURE_UNITS][4];

   GLfloat uPlane[MAX_TEXTURE_UNITS][4];

   GLfloat vPlane[MAX_TEXTURE_UNITS][4];

   GLfloat lambda[MAX_TEXTURE_UNITS];

   GLfloat texWidth[MAX_TEXTURE_UNITS], texHeight[MAX_TEXTURE_UNITS];

   struct sw_span 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])

{

   GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2] + 0.5F;

   if (z < 0.0F)

      return 0;

   else if (z > CHAN_MAXF)

      return (GLchan) CHAN_MAXF;

   return (GLchan) (GLint) z;

}

/*

 * 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) (log(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));

}

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_FOG

#define DO_INDEX

#include "s_aatempline.h"

#define NAME(x) aa_rgba_##x

#define DO_Z

#define DO_FOG

#define DO_RGBA

#include "s_aatempline.h"

#define NAME(x)  aa_tex_rgba_##x

#define DO_Z

#define DO_FOG

#define DO_RGBA

#define DO_TEX

#include "s_aatempline.h"

#define NAME(x)  aa_multitex_rgba_##x

#define DO_Z

#define DO_FOG

#define DO_RGBA

#define DO_MULTITEX

#include "s_aatempline.h"

#define NAME(x)  aa_multitex_spec_##x

#define DO_Z

#define DO_FOG

#define DO_RGBA

#define DO_MULTITEX

#define DO_SPEC

#include "s_aatempline.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._EnabledUnits != 0) {

         if (ctx->Texture._EnabledUnits > 1) {

            /* Multitextured! */

            if (ctx->Light.Model.ColorControl==GL_SEPARATE_SPECULAR_COLOR ||

                ctx->Fog.ColorSumEnabled)

               swrast->Line = aa_multitex_spec_line;

            else

               swrast->Line = aa_multitex_rgba_line;

         }

         else {

            swrast->Line = aa_tex_rgba_line;

         }

      }

      else {

         swrast->Line = aa_rgba_line;

      }

   }

   else {

      /* Color Index */

      swrast->Line = aa_ci_line;

   }

}