The z-sorting sample looked tinted gray because of the final alpha channel copying to the screen. Fixing this revealed that the sort was actually broken in a different way as well, so I fixed that, too.

Review URL: http://codereview.chromium.org/2074015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@47606 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 16 insertions, 6 deletions

diff --git a/o3d/samples/o3d-webgl/client.js b/o3d/samples/o3d-webgl/client.js
index cef816b..9d846c1 100644
--- a/o3d/samples/o3d-webgl/client.js
+++ b/o3d/samples/o3d-webgl/client.js
@@ -438,7 +438,17 @@ o3d.Client.prototype.render = function() {
     this.render_callback(render_event);
   }
   this.then_ = now;
+
+  this.gl.colorMask(true, true, true, true);
+
   this.renderTree(this.renderGraphRoot);
+
+  // When o3d finally draws to the webpage, the alpha channel should be all 1's
+  // So we clear with a color mask to set all alpha bytes to 1 before drawing.
+  // Before we draw again, the color mask gets set back to all true (above).
+  this.gl.colorMask(false, false, false, true);
+  this.gl.clearColor(0.0, 0.0, 0.0, 1.0);
+  this.gl.clear(this.gl.COLOR_BUFFER_BIT);
 };
 
 
diff --git a/o3d/samples/o3d-webgl/draw_list.js b/o3d/samples/o3d-webgl/draw_list.js
index 6132a8b..a9fa9ee 100644
--- a/o3d/samples/o3d-webgl/draw_list.js
+++ b/o3d/samples/o3d-webgl/draw_list.js
@@ -84,11 +84,11 @@ o3d.DrawList.comparePriority_ = function(drawElementInfoA, drawElementInfoB) {
  */
 o3d.DrawList.compareZ_ = function(drawElementInfoA, drawElementInfoB) {
   return o3d.Transform.transformPointZOnly(
-            drawElementInfoA.worldViewProjection,
-            drawElementInfoA.drawElement.owner.zSortPoint) -
-         o3d.Transform.transformPointZOnly(
             drawElementInfoB.worldViewProjection,
-            drawElementInfoB.drawElement.owner.zSortPoint);
+            drawElementInfoB.drawElement.owner.zSortPoint) -
+         o3d.Transform.transformPointZOnly(
+            drawElementInfoA.worldViewProjection,
+            drawElementInfoA.drawElement.owner.zSortPoint);
 };
 
 
diff --git a/o3d/samples/o3d-webgl/transform.js b/o3d/samples/o3d-webgl/transform.js
index 6499da2..5c35a80 100644
--- a/o3d/samples/o3d-webgl/transform.js
+++ b/o3d/samples/o3d-webgl/transform.js
@@ -641,8 +641,8 @@ o3d.Transform.transformPointZOnly = function(m, v) {
   var m2 = m[2];
   var m3 = m[3];
 
-  var d = (v0 * m0[2] + v1 * m1[2] + v2 * m2[2] + m3[2]) /
-          (v0 * m0[3] + v1 * m1[3] + v2 * m2[3] + m3[3]);
+  return (v0 * m0[2] + v1 * m1[2] + v2 * m2[2] + m3[2]) /
+      (v0 * m0[3] + v1 * m1[3] + v2 * m2[3] + m3[3]);
 };