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  1. /*
  2.  * Mesa 3-D graphics library
  3.  * Version:  6.5.3
  4.  *
  5.  * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
  6.  *
  7.  * Permission is hereby granted, free of charge, to any person obtaining a
  8.  * copy of this software and associated documentation files (the "Software"),
  9.  * to deal in the Software without restriction, including without limitation
  10.  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  11.  * and/or sell copies of the Software, and to permit persons to whom the
  12.  * Software is furnished to do so, subject to the following conditions:
  13.  *
  14.  * The above copyright notice and this permission notice shall be included
  15.  * in all copies or substantial portions of the Software.
  16.  *
  17.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18.  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19.  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20.  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  21.  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  22.  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  23.  */
  24.  
  25.  
  26. #include "main/glheader.h"
  27. #include "main/imports.h"
  28. #include "main/macros.h"
  29. #include "main/mtypes.h"
  30. #include "swrast/s_aaline.h"
  31. #include "swrast/s_context.h"
  32. #include "swrast/s_span.h"
  33. #include "swrast/swrast.h"
  34.  
  35.  
  36. #define SUB_PIXEL 4
  37.  
  38.  
  39. /*
  40.  * Info about the AA line we're rendering
  41.  */
  42. struct LineInfo
  43. {
  44.    GLfloat x0, y0;        /* start */
  45.    GLfloat x1, y1;        /* end */
  46.    GLfloat dx, dy;        /* direction vector */
  47.    GLfloat len;           /* length */
  48.    GLfloat halfWidth;     /* half of line width */
  49.    GLfloat xAdj, yAdj;    /* X and Y adjustment for quad corners around line */
  50.    /* for coverage computation */
  51.    GLfloat qx0, qy0;      /* quad vertices */
  52.    GLfloat qx1, qy1;
  53.    GLfloat qx2, qy2;
  54.    GLfloat qx3, qy3;
  55.    GLfloat ex0, ey0;      /* quad edge vectors */
  56.    GLfloat ex1, ey1;
  57.    GLfloat ex2, ey2;
  58.    GLfloat ex3, ey3;
  59.  
  60.    /* DO_Z */
  61.    GLfloat zPlane[4];
  62.    /* DO_RGBA - always enabled */
  63.    GLfloat rPlane[4], gPlane[4], bPlane[4], aPlane[4];
  64.    /* DO_ATTRIBS */
  65.    GLfloat wPlane[4];
  66.    GLfloat attrPlane[FRAG_ATTRIB_MAX][4][4];
  67.    GLfloat lambda[FRAG_ATTRIB_MAX];
  68.    GLfloat texWidth[FRAG_ATTRIB_MAX];
  69.    GLfloat texHeight[FRAG_ATTRIB_MAX];
  70.  
  71.    SWspan span;
  72. };
  73.  
  74.  
  75.  
  76. /*
  77.  * Compute the equation of a plane used to interpolate line fragment data
  78.  * such as color, Z, texture coords, etc.
  79.  * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
  80.  *        z0, and z1 are the end point values to interpolate.
  81.  * Output:  plane - the plane equation.
  82.  *
  83.  * Note: we don't really have enough parameters to specify a plane.
  84.  * We take the endpoints of the line and compute a plane such that
  85.  * the cross product of the line vector and the plane normal is
  86.  * parallel to the projection plane.
  87.  */
  88. static void
  89. compute_plane(GLfloat x0, GLfloat y0, GLfloat x1, GLfloat y1,
  90.               GLfloat z0, GLfloat z1, GLfloat plane[4])
  91. {
  92. #if 0
  93.    /* original */
  94.    const GLfloat px = x1 - x0;
  95.    const GLfloat py = y1 - y0;
  96.    const GLfloat pz = z1 - z0;
  97.    const GLfloat qx = -py;
  98.    const GLfloat qy = px;
  99.    const GLfloat qz = 0;
  100.    const GLfloat a = py * qz - pz * qy;
  101.    const GLfloat b = pz * qx - px * qz;
  102.    const GLfloat c = px * qy - py * qx;
  103.    const GLfloat d = -(a * x0 + b * y0 + c * z0);
  104.    plane[0] = a;
  105.    plane[1] = b;
  106.    plane[2] = c;
  107.    plane[3] = d;
  108. #else
  109.    /* simplified */
  110.    const GLfloat px = x1 - x0;
  111.    const GLfloat py = y1 - y0;
  112.    const GLfloat pz = z0 - z1;
  113.    const GLfloat a = pz * px;
  114.    const GLfloat b = pz * py;
  115.    const GLfloat c = px * px + py * py;
  116.    const GLfloat d = -(a * x0 + b * y0 + c * z0);
  117.    if (a == 0.0 && b == 0.0 && c == 0.0 && d == 0.0) {
  118.       plane[0] = 0.0;
  119.       plane[1] = 0.0;
  120.       plane[2] = 1.0;
  121.       plane[3] = 0.0;
  122.    }
  123.    else {
  124.       plane[0] = a;
  125.       plane[1] = b;
  126.       plane[2] = c;
  127.       plane[3] = d;
  128.    }
  129. #endif
  130. }
  131.  
  132.  
  133. static INLINE void
  134. constant_plane(GLfloat value, GLfloat plane[4])
  135. {
  136.    plane[0] = 0.0;
  137.    plane[1] = 0.0;
  138.    plane[2] = -1.0;
  139.    plane[3] = value;
  140. }
  141.  
  142.  
  143. static INLINE GLfloat
  144. solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
  145. {
  146.    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
  147.    return z;
  148. }
  149.  
  150. #define SOLVE_PLANE(X, Y, PLANE) \
  151.    ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
  152.  
  153.  
  154. /*
  155.  * Return 1 / solve_plane().
  156.  */
  157. static INLINE GLfloat
  158. solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
  159. {
  160.    const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;
  161.    if (denom == 0.0)
  162.       return 0.0;
  163.    else
  164.       return -plane[2] / denom;
  165. }
  166.  
  167.  
  168. /*
  169.  * Solve plane and return clamped GLchan value.
  170.  */
  171. static INLINE GLchan
  172. solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
  173. {
  174.    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
  175. #if CHAN_TYPE == GL_FLOAT
  176.    return CLAMP(z, 0.0F, CHAN_MAXF);
  177. #else
  178.    if (z < 0)
  179.       return 0;
  180.    else if (z > CHAN_MAX)
  181.       return CHAN_MAX;
  182.    return (GLchan) IROUND_POS(z);
  183. #endif
  184. }
  185.  
  186.  
  187. /*
  188.  * Compute mipmap level of detail.
  189.  */
  190. static INLINE GLfloat
  191. compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
  192.                GLfloat invQ, GLfloat width, GLfloat height)
  193. {
  194.    GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
  195.    GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
  196.    GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
  197.    GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
  198.    GLfloat r1 = dudx * dudx + dudy * dudy;
  199.    GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
  200.    GLfloat rho2 = r1 + r2;
  201.    /* return log base 2 of rho */
  202.    if (rho2 == 0.0F)
  203.       return 0.0;
  204.    else
  205.       return (GLfloat) (LOGF(rho2) * 1.442695 * 0.5);/* 1.442695 = 1/log(2) */
  206. }
  207.  
  208.  
  209.  
  210.  
  211. /*
  212.  * Fill in the samples[] array with the (x,y) subpixel positions of
  213.  * xSamples * ySamples sample positions.
  214.  * Note that the four corner samples are put into the first four
  215.  * positions of the array.  This allows us to optimize for the common
  216.  * case of all samples being inside the polygon.
  217.  */
  218. static void
  219. make_sample_table(GLint xSamples, GLint ySamples, GLfloat samples[][2])
  220. {
  221.    const GLfloat dx = 1.0F / (GLfloat) xSamples;
  222.    const GLfloat dy = 1.0F / (GLfloat) ySamples;
  223.    GLint x, y;
  224.    GLint i;
  225.  
  226.    i = 4;
  227.    for (x = 0; x < xSamples; x++) {
  228.       for (y = 0; y < ySamples; y++) {
  229.          GLint j;
  230.          if (x == 0 && y == 0) {
  231.             /* lower left */
  232.             j = 0;
  233.          }
  234.          else if (x == xSamples - 1 && y == 0) {
  235.             /* lower right */
  236.             j = 1;
  237.          }
  238.          else if (x == 0 && y == ySamples - 1) {
  239.             /* upper left */
  240.             j = 2;
  241.          }
  242.          else if (x == xSamples - 1 && y == ySamples - 1) {
  243.             /* upper right */
  244.             j = 3;
  245.          }
  246.          else {
  247.             j = i++;
  248.          }
  249.          samples[j][0] = x * dx + 0.5F * dx;
  250.          samples[j][1] = y * dy + 0.5F * dy;
  251.       }
  252.    }
  253. }
  254.  
  255.  
  256.  
  257. /*
  258.  * Compute how much of the given pixel's area is inside the rectangle
  259.  * defined by vertices v0, v1, v2, v3.
  260.  * Vertices MUST be specified in counter-clockwise order.
  261.  * Return:  coverage in [0, 1].
  262.  */
  263. static GLfloat
  264. compute_coveragef(const struct LineInfo *info,
  265.                   GLint winx, GLint winy)
  266. {
  267.    static GLfloat samples[SUB_PIXEL * SUB_PIXEL][2];
  268.    static GLboolean haveSamples = GL_FALSE;
  269.    const GLfloat x = (GLfloat) winx;
  270.    const GLfloat y = (GLfloat) winy;
  271.    GLint stop = 4, i;
  272.    GLfloat insideCount = SUB_PIXEL * SUB_PIXEL;
  273.  
  274.    if (!haveSamples) {
  275.       make_sample_table(SUB_PIXEL, SUB_PIXEL, samples);
  276.       haveSamples = GL_TRUE;
  277.    }
  278.  
  279. #if 0 /*DEBUG*/
  280.    {
  281.       const GLfloat area = dx0 * dy1 - dx1 * dy0;
  282.       assert(area >= 0.0);
  283.    }
  284. #endif
  285.  
  286.    for (i = 0; i < stop; i++) {
  287.       const GLfloat sx = x + samples[i][0];
  288.       const GLfloat sy = y + samples[i][1];
  289.       const GLfloat fx0 = sx - info->qx0;
  290.       const GLfloat fy0 = sy - info->qy0;
  291.       const GLfloat fx1 = sx - info->qx1;
  292.       const GLfloat fy1 = sy - info->qy1;
  293.       const GLfloat fx2 = sx - info->qx2;
  294.       const GLfloat fy2 = sy - info->qy2;
  295.       const GLfloat fx3 = sx - info->qx3;
  296.       const GLfloat fy3 = sy - info->qy3;
  297.       /* cross product determines if sample is inside or outside each edge */
  298.       GLfloat cross0 = (info->ex0 * fy0 - info->ey0 * fx0);
  299.       GLfloat cross1 = (info->ex1 * fy1 - info->ey1 * fx1);
  300.       GLfloat cross2 = (info->ex2 * fy2 - info->ey2 * fx2);
  301.       GLfloat cross3 = (info->ex3 * fy3 - info->ey3 * fx3);
  302.       /* Check if the sample is exactly on an edge.  If so, let cross be a
  303.        * positive or negative value depending on the direction of the edge.
  304.        */
  305.       if (cross0 == 0.0F)
  306.          cross0 = info->ex0 + info->ey0;
  307.       if (cross1 == 0.0F)
  308.          cross1 = info->ex1 + info->ey1;
  309.       if (cross2 == 0.0F)
  310.          cross2 = info->ex2 + info->ey2;
  311.       if (cross3 == 0.0F)
  312.          cross3 = info->ex3 + info->ey3;
  313.       if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F || cross3 < 0.0F) {
  314.          /* point is outside quadrilateral */
  315.          insideCount -= 1.0F;
  316.          stop = SUB_PIXEL * SUB_PIXEL;
  317.       }
  318.    }
  319.    if (stop == 4)
  320.       return 1.0F;
  321.    else
  322.       return insideCount * (1.0F / (SUB_PIXEL * SUB_PIXEL));
  323. }
  324.  
  325.  
  326. typedef void (*plot_func)(struct gl_context *ctx, struct LineInfo *line,
  327.                           int ix, int iy);
  328.                          
  329.  
  330.  
  331. /*
  332.  * Draw an AA line segment (called many times per line when stippling)
  333.  */
  334. static void
  335. segment(struct gl_context *ctx,
  336.         struct LineInfo *line,
  337.         plot_func plot,
  338.         GLfloat t0, GLfloat t1)
  339. {
  340.    const GLfloat absDx = (line->dx < 0.0F) ? -line->dx : line->dx;
  341.    const GLfloat absDy = (line->dy < 0.0F) ? -line->dy : line->dy;
  342.    /* compute the actual segment's endpoints */
  343.    const GLfloat x0 = line->x0 + t0 * line->dx;
  344.    const GLfloat y0 = line->y0 + t0 * line->dy;
  345.    const GLfloat x1 = line->x0 + t1 * line->dx;
  346.    const GLfloat y1 = line->y0 + t1 * line->dy;
  347.  
  348.    /* compute vertices of the line-aligned quadrilateral */
  349.    line->qx0 = x0 - line->yAdj;
  350.    line->qy0 = y0 + line->xAdj;
  351.    line->qx1 = x0 + line->yAdj;
  352.    line->qy1 = y0 - line->xAdj;
  353.    line->qx2 = x1 + line->yAdj;
  354.    line->qy2 = y1 - line->xAdj;
  355.    line->qx3 = x1 - line->yAdj;
  356.    line->qy3 = y1 + line->xAdj;
  357.    /* compute the quad's edge vectors (for coverage calc) */
  358.    line->ex0 = line->qx1 - line->qx0;
  359.    line->ey0 = line->qy1 - line->qy0;
  360.    line->ex1 = line->qx2 - line->qx1;
  361.    line->ey1 = line->qy2 - line->qy1;
  362.    line->ex2 = line->qx3 - line->qx2;
  363.    line->ey2 = line->qy3 - line->qy2;
  364.    line->ex3 = line->qx0 - line->qx3;
  365.    line->ey3 = line->qy0 - line->qy3;
  366.  
  367.    if (absDx > absDy) {
  368.       /* X-major line */
  369.       GLfloat dydx = line->dy / line->dx;
  370.       GLfloat xLeft, xRight, yBot, yTop;
  371.       GLint ix, ixRight;
  372.       if (x0 < x1) {
  373.          xLeft = x0 - line->halfWidth;
  374.          xRight = x1 + line->halfWidth;
  375.          if (line->dy >= 0.0) {
  376.             yBot = y0 - 3.0F * line->halfWidth;
  377.             yTop = y0 + line->halfWidth;
  378.          }
  379.          else {
  380.             yBot = y0 - line->halfWidth;
  381.             yTop = y0 + 3.0F * line->halfWidth;
  382.          }
  383.       }
  384.       else {
  385.          xLeft = x1 - line->halfWidth;
  386.          xRight = x0 + line->halfWidth;
  387.          if (line->dy <= 0.0) {
  388.             yBot = y1 - 3.0F * line->halfWidth;
  389.             yTop = y1 + line->halfWidth;
  390.          }
  391.          else {
  392.             yBot = y1 - line->halfWidth;
  393.             yTop = y1 + 3.0F * line->halfWidth;
  394.          }
  395.       }
  396.  
  397.       /* scan along the line, left-to-right */
  398.       ixRight = (GLint) (xRight + 1.0F);
  399.  
  400.       /*printf("avg span height: %g\n", yTop - yBot);*/
  401.       for (ix = (GLint) xLeft; ix < ixRight; ix++) {
  402.          const GLint iyBot = (GLint) yBot;
  403.          const GLint iyTop = (GLint) (yTop + 1.0F);
  404.          GLint iy;
  405.          /* scan across the line, bottom-to-top */
  406.          for (iy = iyBot; iy < iyTop; iy++) {
  407.             (*plot)(ctx, line, ix, iy);
  408.          }
  409.          yBot += dydx;
  410.          yTop += dydx;
  411.       }
  412.    }
  413.    else {
  414.       /* Y-major line */
  415.       GLfloat dxdy = line->dx / line->dy;
  416.       GLfloat yBot, yTop, xLeft, xRight;
  417.       GLint iy, iyTop;
  418.       if (y0 < y1) {
  419.          yBot = y0 - line->halfWidth;
  420.          yTop = y1 + line->halfWidth;
  421.          if (line->dx >= 0.0) {
  422.             xLeft = x0 - 3.0F * line->halfWidth;
  423.             xRight = x0 + line->halfWidth;
  424.          }
  425.          else {
  426.             xLeft = x0 - line->halfWidth;
  427.             xRight = x0 + 3.0F * line->halfWidth;
  428.          }
  429.       }
  430.       else {
  431.          yBot = y1 - line->halfWidth;
  432.          yTop = y0 + line->halfWidth;
  433.          if (line->dx <= 0.0) {
  434.             xLeft = x1 - 3.0F * line->halfWidth;
  435.             xRight = x1 + line->halfWidth;
  436.          }
  437.          else {
  438.             xLeft = x1 - line->halfWidth;
  439.             xRight = x1 + 3.0F * line->halfWidth;
  440.          }
  441.       }
  442.  
  443.       /* scan along the line, bottom-to-top */
  444.       iyTop = (GLint) (yTop + 1.0F);
  445.  
  446.       /*printf("avg span width: %g\n", xRight - xLeft);*/
  447.       for (iy = (GLint) yBot; iy < iyTop; iy++) {
  448.          const GLint ixLeft = (GLint) xLeft;
  449.          const GLint ixRight = (GLint) (xRight + 1.0F);
  450.          GLint ix;
  451.          /* scan across the line, left-to-right */
  452.          for (ix = ixLeft; ix < ixRight; ix++) {
  453.             (*plot)(ctx, line, ix, iy);
  454.          }
  455.          xLeft += dxdy;
  456.          xRight += dxdy;
  457.       }
  458.    }
  459. }
  460.  
  461.  
  462. #define NAME(x) aa_rgba_##x
  463. #define DO_Z
  464. #include "s_aalinetemp.h"
  465.  
  466.  
  467. #define NAME(x)  aa_general_rgba_##x
  468. #define DO_Z
  469. #define DO_ATTRIBS
  470. #include "s_aalinetemp.h"
  471.  
  472.  
  473.  
  474. void
  475. _swrast_choose_aa_line_function(struct gl_context *ctx)
  476. {
  477.    SWcontext *swrast = SWRAST_CONTEXT(ctx);
  478.  
  479.    ASSERT(ctx->Line.SmoothFlag);
  480.  
  481.    if (ctx->Texture._EnabledCoordUnits != 0
  482.        || ctx->FragmentProgram._Current
  483.        || (ctx->Light.Enabled &&
  484.            ctx->Light.Model.ColorControl == GL_SEPARATE_SPECULAR_COLOR)
  485.        || ctx->Fog.ColorSumEnabled
  486.        || swrast->_FogEnabled) {
  487.       swrast->Line = aa_general_rgba_line;
  488.    }
  489.    else {
  490.       swrast->Line = aa_rgba_line;
  491.    }
  492. }
  493.