From fd78ee7284351ee6284299fcf57559a78da3b48a Mon Sep 17 00:00:00 2001
From: "gman@google.com" <gman@google.com@0039d316-1c4b-4281-b951-d872f2087c98>
Date: Tue, 28 Jul 2009 02:38:29 +0000
Subject: Changes to picking example to show how to get the surface normal for
 the spot picked.

Apparently no screenshots are taken for picking
so no deps files need up be updated

Review URL: http://codereview.chromium.org/159442

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@21805 0039d316-1c4b-4281-b951-d872f2087c98
---
 o3d/samples/picking.html | 57 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)

(limited to 'o3d/samples/picking.html')

diff --git a/o3d/samples/picking.html b/o3d/samples/picking.html
index cd9ddd1..ae62ebd 100644
--- a/o3d/samples/picking.html
+++ b/o3d/samples/picking.html
@@ -56,7 +56,7 @@ O3D Picking Example.
 <!-- Include default javascript library functions-->
 <script type="text/javascript" src="o3djs/base.js"></script>
 <!-- Our javascript code -->
-<script type="text/javascript">
+<script type="text/javascript" id="o3d">
 o3djs.require('o3djs.util');
 o3djs.require('o3djs.math');
 o3djs.require('o3djs.rendergraph');
@@ -64,6 +64,7 @@ o3djs.require('o3djs.pack');
 o3djs.require('o3djs.camera');
 o3djs.require('o3djs.picking');
 o3djs.require('o3djs.scene');
+o3djs.require('o3djs.debug');
 
 // Events
 // init() once the page has finished loading.
@@ -71,6 +72,9 @@ o3djs.require('o3djs.scene');
 window.onload = init;
 window.onunload = unload;
 
+// constants
+var NORMAL_SCALE_FACTOR = 2.0;
+
 // global variables
 var g_o3d;
 var g_math;
@@ -79,6 +83,9 @@ var g_pack;
 var g_viewInfo;
 var g_treeInfo;  // information about the transform graph.
 var g_pickInfoElem;
+var g_debugHelper;
+var g_debugLineGroup;
+var g_debugLine;
 var g_selectedInfo = null;
 var g_flashTimer = 0;
 var g_highlightMaterial;
@@ -135,13 +142,53 @@ function pick(e) {
   unSelectAll();
 
   // Update the entire tree in case anything moved.
+  // NOTE: This function is very SLOW!
+  // If you really want to use picking you should manually update only those
+  // transforms and shapes that moved, were added, or deleted by writing your
+  // own picking library. You should also make sure that you are only
+  // considering things that are pickable. By that I mean if you have a scene of
+  // a meadow with trees, grass, bushes, and animals and the only thing the user
+  // can pick is the animals then put the animals on their own sub branch of the
+  // transform graph and only pick against that subgraph.
+  // Even better, make a separate transform graph with only cubes on it to
+  // represent the animals and use that instead of the actual animals.
   g_treeInfo.update();
 
   var pickInfo = g_treeInfo.pick(worldRay);
   if (pickInfo) {
     select(pickInfo);
     g_pickInfoElem.innerHTML = pickInfo.shapeInfo.shape.name;
+
+    // Display the normal
+    // NOTE: Lookup the normal with this function is very SLOW!!
+    // If you need performance, for a game or something, you should consider
+    // other methods.
+    var normal = o3djs.element.getNormalForTriangle(
+        pickInfo.element,
+        pickInfo.rayIntersectionInfo.primitiveIndex);
+
+    // Convert the normal from local to world space.
+    normal = g_math.matrix4.transformNormal(
+        pickInfo.shapeInfo.parent.transform.worldMatrix,
+        normal);
+
+    // Remove the scale from the normal.
+    normal = g_math.normalize(normal);
+
+    // Get the world position of the collision.
+    var worldPosition = pickInfo.worldIntersectionPosition;
+
+    // Add the normal to it to get a point in space above it with some
+    // multiplier to scale it.
+    var normalSpot = g_math.addVector(
+        worldPosition,
+        g_math.mulVectorScalar(normal, NORMAL_SCALE_FACTOR));
+
+    // Move our debug line to show the normal
+    g_debugLine.setVisible(true);
+    g_debugLine.setEndPoints(worldPosition, normalSpot);
   } else {
+    g_debugLine.setVisible(false);
     g_pickInfoElem.innerHTML = '--nothing--';
   }
 }
@@ -238,6 +285,14 @@ function initStep2(clientElements) {
       g_client.root,
       g_client.renderGraphRoot);
 
+  // Use the debug library to create a line we can position to show
+  // the normal.
+  g_debugHelper = o3djs.debug.createDebugHelper(g_client.createPack(),
+                                                g_viewInfo);
+  g_debugLineGroup = g_debugHelper.createDebugLineGroup(g_client.root);
+  g_debugLine = g_debugLineGroup.addLine();
+  g_debugLine.setColor([0,1,0,1]);
+
   // Create a material for highlighting.
   g_highlightMaterial = g_pack.createObject('Material');
   g_highlightMaterial.drawList = g_viewInfo.performanceDrawList;
-- 
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