fixed AA sampling problem, misc clean-up

diff --git a/src/mesa/main/points.c b/src/mesa/main/points.c
index 2aebb72472df7ed32e121efc9dcc6690e6fcc251..fe4810eaebecc85b06892fe9e500331a1a4ec417 100644 (file)
--- a/src/mesa/main/points.c
+++ b/src/mesa/main/points.c
@@ -1,4 +1,4 @@
-/* $Id: points.c,v 1.10 2000/06/28 23:11:10 brianp Exp $ */
+/* $Id: points.c,v 1.11 2000/07/15 03:13:43 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -521,6 +521,17 @@ multitextured_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
 }
 
 
+/*
+ * NOTES on aa point rasterization:
+ *
+ * Let d = distance of fragment center from vertex.
+ * if d < rmin2 then
+ *    fragment has 100% coverage
+ * else if d > rmax2 then
+ *    fragment has 0% coverage
+ * else
+ *    fragement has % coverage = (d - rmin2) / (rmax2 - rmin2)
+ */
 
 
 /*
@@ -534,7 +545,7 @@ antialiased_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
    const GLfloat radius = ctx->Point.Size * 0.5F;
    const GLfloat rmin = radius - 0.7071F;  /* 0.7071 = sqrt(2)/2 */
    const GLfloat rmax = radius + 0.7071F;
-   const GLfloat rmin2 = rmin * rmin;
+   const GLfloat rmin2 = MAX2(0.0, rmin * rmin);
    const GLfloat rmax2 = rmax * rmax;
    const GLfloat cscale = 256.0F / (rmax2 - rmin2);
    GLuint i;
@@ -546,11 +557,13 @@ antialiased_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
             GLint red, green, blue, alpha;
             GLfloat s, t, u;
             GLfloat s1, t1, u1;
+            GLfloat vx = VB->Win.data[i][0];
+            GLfloat vy = VB->Win.data[i][1];
 
-            GLint xmin = (GLint) (VB->Win.data[i][0] - radius);
-            GLint xmax = (GLint) (VB->Win.data[i][0] + radius);
-            GLint ymin = (GLint) (VB->Win.data[i][1] - radius);
-            GLint ymax = (GLint) (VB->Win.data[i][1] + radius);
+            GLint xmin = (GLint) (vx - radius);
+            GLint xmax = (GLint) (vx + radius);
+            GLint ymin = (GLint) (vy - radius);
+            GLint ymax = (GLint) (vy + radius);
             GLint z = (GLint) (VB->Win.data[i][2] + ctx->PointZoffset);
 
             red   = VB->ColorPtr->data[i][0];
@@ -621,15 +634,19 @@ antialiased_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
               }
            }
 
-            for (y=ymin;y<=ymax;y++) {
-               for (x=xmin;x<=xmax;x++) {
-                  GLfloat dx = x/*+0.5F*/ - VB->Win.data[i][0];
-                  GLfloat dy = y/*+0.5F*/ - VB->Win.data[i][1];
-                  GLfloat dist2 = dx*dx + dy*dy;
-                  if (dist2<rmax2) {
+            /* translate by a half pixel to simplify math below */
+            vx -= 0.5F;
+            vx -= 0.5F;
+
+            for (y = ymin; y <= ymax; y++) {
+               for (x = xmin; x <= xmax; x++) {
+                  const GLfloat dx = x - vx;
+                  const GLfloat dy = y - vy;
+                  const GLfloat dist2 = dx*dx + dy*dy;
+                  if (dist2 < rmax2) {
                      alpha = VB->ColorPtr->data[i][3];
-                     if (dist2>=rmin2) {
-                        GLint coverage = (GLint) (256.0F-(dist2-rmin2)*cscale);
+                     if (dist2 >= rmin2) {
+                        GLint coverage = (GLint) (256.0F - (dist2 - rmin2) * cscale);
                         /* coverage is in [0,256] */
                         alpha = (alpha * coverage) >> 8;
                      }
@@ -656,25 +673,29 @@ antialiased_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
             GLint x, y, z;
             GLint red, green, blue, alpha;
 
-            xmin = (GLint) (VB->Win.data[i][0] - radius);
-            xmax = (GLint) (VB->Win.data[i][0] + radius);
-            ymin = (GLint) (VB->Win.data[i][1] - radius);
-            ymax = (GLint) (VB->Win.data[i][1] + radius);
+            xmin = (GLint) (VB->Win.data[i][0] - 0.0 - radius);
+            xmax = (GLint) (VB->Win.data[i][0] - 0.0 + radius);
+            ymin = (GLint) (VB->Win.data[i][1] - 0.0 - radius);
+            ymax = (GLint) (VB->Win.data[i][1] - 0.0 + radius);
             z = (GLint) (VB->Win.data[i][2] + ctx->PointZoffset);
 
             red   = VB->ColorPtr->data[i][0];
             green = VB->ColorPtr->data[i][1];
             blue  = VB->ColorPtr->data[i][2];
 
-            for (y=ymin;y<=ymax;y++) {
-               for (x=xmin;x<=xmax;x++) {
-                  GLfloat dx = x/*+0.5F*/ - VB->Win.data[i][0];
-                  GLfloat dy = y/*+0.5F*/ - VB->Win.data[i][1];
-                  GLfloat dist2 = dx*dx + dy*dy;
-                  if (dist2<rmax2) {
+            /*
+            printf("point %g, %g\n", VB->Win.data[i][0], VB->Win.data[i][1]);
+            printf("%d..%d X %d..%d\n", xmin, xmax, ymin, ymax);
+            */
+            for (y = ymin; y <= ymax; y++) {
+               for (x = xmin; x <= xmax; x++) {
+                  const GLfloat dx = x + 0.5F - VB->Win.data[i][0];
+                  const GLfloat dy = y + 0.5F - VB->Win.data[i][1];
+                  const GLfloat dist2 = dx*dx + dy*dy;
+                  if (dist2 < rmax2) {
                      alpha = VB->ColorPtr->data[i][3];
-                     if (dist2>=rmin2) {
-                        GLint coverage = (GLint) (256.0F-(dist2-rmin2)*cscale);
+                     if (dist2 >= rmin2) {
+                        GLint coverage = (GLint) (256.0F - (dist2 - rmin2) * cscale);
                         /* coverage is in [0,256] */
                         alpha = (alpha * coverage) >> 8;
                      }
@@ -1104,9 +1125,9 @@ dist_atten_antialiased_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
             }
             rmin = radius - 0.7071F;  /* 0.7071 = sqrt(2)/2 */
             rmax = radius + 0.7071F;
-            rmin2 = rmin*rmin;
-            rmax2 = rmax*rmax;
-            cscale = 256.0F / (rmax2-rmin2);
+            rmin2 = MAX2(0.0, rmin * rmin);
+            rmax2 = rmax * rmax;
+            cscale = 256.0F / (rmax2 - rmin2);
 
             xmin = (GLint) (VB->Win.data[i][0] - radius);
             xmax = (GLint) (VB->Win.data[i][0] + radius);
@@ -1184,9 +1205,9 @@ dist_atten_antialiased_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
 
             for (y = ymin; y <= ymax; y++) {
                for (x = xmin; x <= xmax; x++) {
-                  GLfloat dx = x/*+0.5F*/ - VB->Win.data[i][0];
-                  GLfloat dy = y/*+0.5F*/ - VB->Win.data[i][1];
-                  GLfloat dist2 = dx*dx + dy*dy;
+                  const GLfloat dx = x + 0.5F - VB->Win.data[i][0];
+                  const GLfloat dy = y + 0.5F - VB->Win.data[i][1];
+                  const GLfloat dist2 = dx*dx + dy*dy;
                   if (dist2 < rmax2) {
                      alpha = VB->ColorPtr->data[i][3];
                      if (dist2 >= rmin2) {
@@ -1230,7 +1251,7 @@ dist_atten_antialiased_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
             }
             rmin = radius - 0.7071F;  /* 0.7071 = sqrt(2)/2 */
             rmax = radius + 0.7071F;
-            rmin2 = rmin * rmin;
+            rmin2 = MAX2(0.0, rmin * rmin);
             rmax2 = rmax * rmax;
             cscale = 256.0F / (rmax2 - rmin2);
 
@@ -1246,9 +1267,9 @@ dist_atten_antialiased_rgba_points( GLcontext *ctx, GLuint first, GLuint last )
 
             for (y = ymin; y <= ymax; y++) {
                for (x = xmin; x <= xmax; x++) {
-                  GLfloat dx = x/*+0.5F*/ - VB->Win.data[i][0];
-                  GLfloat dy = y/*+0.5F*/ - VB->Win.data[i][1];
-                  GLfloat dist2 = dx * dx + dy * dy;
+                  const GLfloat dx = x + 0.5F - VB->Win.data[i][0];
+                  const GLfloat dy = y + 0.5F - VB->Win.data[i][1];
+                  const GLfloat dist2 = dx * dx + dy * dy;
                   if (dist2 < rmax2) {
                     alpha = VB->ColorPtr->data[i][3];
                      if (dist2 >= rmin2) {