New implementation of antialiased lines. Mesa should now pass the remaining

GL conformance tests for AA lines (but not tried yet).
TODO: improve code sharing with the AA triangle code.

1 files changed, 509 insertions, 0 deletions

diff --git a/src/mesa/swrast/s_aaline.c b/src/mesa/swrast/s_aaline.c
new file mode 100644
index 0000000000..377e6072c7
--- /dev/null
+++ b/src/mesa/swrast/s_aaline.c
@@ -0,0 +1,509 @@
+/* $Id: s_aaline.c,v 1.1 2000/11/05 23:15:16 brianp Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version:  3.5
+ * 
+ * Copyright (C) 1999-2000  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_pb.h"
+#include "swrast/s_context.h"
+#include "swrast/swrast.h"
+#include "types.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];
+};
+
+
+
+/*
+ * 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);
+   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])
+{
+   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])
+{
+   GLfloat z = -plane[2] / (plane[3] + plane[0] * x + plane[1] * y);
+   return z;
+}
+
+
+/*
+ * 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 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 */
+   return 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;
+         samples[j][1] = y * 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, const struct LineInfo *line,
+                          struct pixel_buffer *pb, 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,
+        struct pixel_buffer *pb,
+        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 - 3.0 * line->halfWidth;
+            yTop = y0 + line->halfWidth;
+         }
+         else {
+            yBot = y0 - line->halfWidth;
+            yTop = y0 + 3.0 * line->halfWidth;
+         }
+      }
+      else {
+         xLeft = x1 - line->halfWidth;
+         xRight = x0 + line->halfWidth;
+         if (line->dy <= 0.0) {
+            yBot = y1 - 3.0 * line->halfWidth;
+            yTop = y1 + line->halfWidth;
+         }
+         else {
+            yBot = y1 - line->halfWidth;
+            yTop = y1 + 3.0 * 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, pb, 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 - 3.0 * line->halfWidth;
+            xRight = x0 + line->halfWidth;
+         }
+         else {
+            xLeft = x0 - line->halfWidth;
+            xRight = x0 + 3.0 * line->halfWidth;
+         }
+      }
+      else {
+         yBot = y1 - line->halfWidth;
+         yTop = y0 + line->halfWidth;
+         if (line->dx <= 0.0) {
+            xLeft = x1 - 3.0 * line->halfWidth;
+            xRight = x1 + line->halfWidth;
+         }
+         else {
+            xLeft = x1 - line->halfWidth;
+            xRight = x1 + 3.0 * 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, pb, ix, iy);
+         }
+         xLeft += dxdy;
+         xRight += dxdy;
+      }
+   }
+}
+
+
+#define NAME(x) aa_ci_##x
+#define DO_Z
+#define DO_FOG
+#define DO_INDEX
+#include "s_aalinetemp.h"
+
+
+#define NAME(x) aa_rgba_##x
+#define DO_Z
+#define DO_FOG
+#define DO_RGBA
+#include "s_aalinetemp.h"
+
+
+#define NAME(x)  aa_tex_rgba_##x
+#define DO_Z
+#define DO_FOG
+#define DO_RGBA
+#define DO_TEX
+#include "s_aalinetemp.h"
+
+
+#define NAME(x)  aa_multitex_rgba_##x
+#define DO_Z
+#define DO_RGBA
+#define DO_MULTITEX
+#define DO_SPEC
+#include "s_aalinetemp.h"
+
+
+
+void
+_swrast_choose_aa_line_function(GLcontext *ctx)
+{
+   SWcontext *swrast = SWRAST_CONTEXT(ctx);
+
+   ASSERT(ctx->Line.SmoothFlag);
+
+   if (ctx->Visual.RGBAflag) {
+      /* RGBA */
+      if (ctx->Texture._ReallyEnabled) {
+         if (ctx->Texture._MultiTextureEnabled
+             || ctx->Light.Model.ColorControl==GL_SEPARATE_SPECULAR_COLOR
+             || ctx->Fog.ColorSumEnabled)
+            /* Multitextured! */
+            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;
+   }
+}
+