Sorts drawlists by priority or by depth as indicated by the flag in the DrawPass.

Review URL: http://codereview.chromium.org/2075003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@47459 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 69 insertions, 7 deletions

diff --git a/o3d/samples/o3d-webgl/draw_list.js b/o3d/samples/o3d-webgl/draw_list.js
index 875f237..6132a8b 100644
--- a/o3d/samples/o3d-webgl/draw_list.js
+++ b/o3d/samples/o3d-webgl/draw_list.js
@@ -69,10 +69,55 @@ o3d.DrawList.BY_PRIORITY = 2;
 
 
 /**
+ * Compare function for by-priority sort.
+ */
+o3d.DrawList.comparePriority_ = function(drawElementInfoA, drawElementInfoB) {
+  return drawElementInfoA.drawElement.owner.priority -
+         drawElementInfoB.drawElement.owner.priority;
+};
+
+
+/**
+ * Compare function for by-z-coordinate sort.
+ * @param {!o3d.DrawElement} drawElementInfoA
+ * @param {!o3d.DrawElement} 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);
+};
+
+
+/**
+ * Sorts this list according to the given sort method.
+ * @param {o3d.DrawList.SortMethod} sort_method Which method to use.
+ * @private
+ */
+o3d.DrawList.prototype.sort_ = function(sort_method) {
+  switch (sort_method) {
+    case o3d.DrawList.BY_PRIORITY:
+      this.list_.sort(o3d.DrawList.comparePriority_);
+      break;
+
+    case o3d.DrawList.BY_Z_ORDER:
+      this.list_.sort(o3d.DrawList.compareZ_);
+      break;
+
+    case o3d.DrawList.BY_PERFORMANCE:
+    default:
+      break;
+  }
+};
+
+
+/**
  * Renders the draw list.
  */
 o3d.DrawList.prototype.render = function() {
-  // TODO(petersont): Add sort.
   for (var i = 0; i < this.list_.length; ++i) {
     var drawElementInfo = this.list_[i];
     var world = drawElementInfo.world;
diff --git a/o3d/samples/o3d-webgl/draw_pass.js b/o3d/samples/o3d-webgl/draw_pass.js
index 600f641..c02601b 100644
--- a/o3d/samples/o3d-webgl/draw_pass.js
+++ b/o3d/samples/o3d-webgl/draw_pass.js
@@ -32,7 +32,7 @@
 
 /**
  * A DrawPass renders a DrawList.
- * 
+ *
  * @param {o3d.DrawList} drawList The DrawList used by this DrawPass.
  * @param {o3d.DrawPass.SortMethod} sortMethod ParamInteger The method
  *     of sorting this DrawPass.
@@ -69,6 +69,7 @@ o3d.ParamObject.setUpO3DParam_(o3d.DrawPass, 'sortMethod', 'ParamInteger');
  */
 o3d.DrawPass.prototype.before = function() {
   if (this.drawList) {
+    this.drawList.sort_(this.sortMethod);
     this.drawList.render();
   }
 };
diff --git a/o3d/samples/o3d-webgl/transform.js b/o3d/samples/o3d-webgl/transform.js
index 929abfd..6499da2 100644
--- a/o3d/samples/o3d-webgl/transform.js
+++ b/o3d/samples/o3d-webgl/transform.js
@@ -612,11 +612,6 @@ o3d.Transform.transformPoint = function(m, v) {
   var v0 = v[0];
   var v1 = v[1];
   var v2 = v[2];
-
-  if (!m) {
-    debugger;
-  }
-
   var m0 = m[0];
   var m1 = m[1];
   var m2 = m[2];
@@ -629,6 +624,27 @@ o3d.Transform.transformPoint = function(m, v) {
 };
 
 
+/**
+ * Takes a 4-by-4 matrix and a vector with 3 entries,
+ * interprets the vector as a point, transforms that point by the matrix,
+ * returning the z-component of the result only.
+ * @param {!o3djs.math.Matrix4} m The matrix.
+ * @param {!o3djs.math.Vector3} v The point.
+ * @return {number} The z coordinate of the transformed point.
+ */
+o3d.Transform.transformPointZOnly = function(m, v) {
+  var v0 = v[0];
+  var v1 = v[1];
+  var v2 = v[2];
+  var m0 = m[0];
+  var m1 = m[1];
+  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]);
+};
+
 
 /**
  * Pre-composes the local matrix of this Transform with a rotation about the