o3d-webgl: convolution shader and error texture.

samples/o3d-webgl/sampler.js

 /*
  * Copyright 2010, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 232 matching lines @@
     case o3d.Sampler.LINEAR:
     case o3d.Sampler.ANISOTROPIC:
       return this.gl.LINEAR;
   }
   this.gl.client.error_callback("Unknown filter.");
   return this.gl.LINEAR;
 }
 
 
 /**
+ * A default Sampler that has no texture, thus uses the client's error texture.
+ *
+ * @type {!o3d.Sampler}
+ * @private
+ */
+o3d.Sampler.defaultSampler_ = new o3d.Sampler();
+o3d.Sampler.defaultSampler_.magFilter = o3d.Sampler.POINT;
+
+/**
  * Binds the texture for this sampler and sets texParameters according to the
  * states of the sampler.
  */
 o3d.Sampler.prototype.bindAndSetParameters_ = function() {
+  var currentTexture = null;
   if (this.texture) {
-    var mip_filter = this.mipFilter;
-    if (this.texture.levels == 1) {
-      mip_filter = o3d.Sampler.NONE;
-    }
+    currentTexture = this.texture;
+  } else if (!this.gl.client.reportErrors_()) {
+    currentTexture = this.gl.client.error_texture_;
+  } else {
+    currentTexture = this.gl.client.fallback_error_texture_;
+    this.gl.client.error_callback("Missing texture for sampler " + this.name);
+  }
 
-    this.texture.bindAndSetParameters_(
-      this.convertAddressMode_(this.addressModeU),
-      this.convertAddressMode_(this.addressModeV),
-      this.convertMinFilter_(this.minFilter, mip_filter),
-      this.convertMagFilter_(this.magFilter));
-  } else {
-    this.gl.client.error_callback("Sampler used with no texture set.");
-    return;
+  var mip_filter = this.mipFilter;
+  if (currentTexture.levels == 1) {
+    mip_filter = o3d.Sampler.NONE;
   }
+  currentTexture.bindAndSetParameters_(
+    this.convertAddressMode_(this.addressModeU),
+    this.convertAddressMode_(this.addressModeV),
+    this.convertMinFilter_(this.minFilter, mip_filter),
+    this.convertMagFilter_(this.magFilter));
 }