History: Displaying 2D Backgrounds
Preview of version: 3
A frequently asked question is how to display a 2D background image in OGRE. Here is an example of how to achieve this using the Rectangle2D class. This also demonstrates e.g. how to easily scroll the background.
Copy to clipboard
// Create background material MaterialPtr material = MaterialManager::getSingleton().create("Background", "General"); material->getTechnique(0)->getPass(0)->createTextureUnitState("rockwall.tga"); material->getTechnique(0)->getPass(0)->setDepthCheckEnabled(false); material->getTechnique(0)->getPass(0)->setDepthWriteEnabled(false); material->getTechnique(0)->getPass(0)->setLightingEnabled(false); // Create background rectangle covering the whole screen Rectangle2D* rect = new Rectangle2D(true); rect->setCorners(-1.0, 1.0, 1.0, -1.0); rect->setMaterial("Background"); // Render the background before everything else rect->setRenderQueueGroup(RENDER_QUEUE_BACKGROUND); // Hacky, but we need to set the bounding box to something big // NOTE: If you are using Eihort, please see the note below on setting the bounding box rect->setBoundingBox(AxisAlignedBox(-100000.0*Vector3::UNIT_SCALE, 100000.0*Vector3::UNIT_SCALE)); // Attach background to the scene SceneNode* node = mSceneMgr->getRootSceneNode()->createChildSceneNode("Background"); node->attachObject(rect); // Example of background scrolling material->getTechnique(0)->getPass(0)->getTextureUnitState(0)->setScrollAnimation(-0.25, 0.0);
Note: You cannot add the 2D Rectangle directly to the root scene node. It will not show up.
Note on bounding box in Eihort: In Eihort bounding boxes can now be infinite, which means that an object with an infinite bounding box will always be visible. This is practical in connection with Rectangle2D and replaces the hack of setting the bounding box to something very big. Instead just do this when setting the bounding box:
Copy to clipboard
// Use infinite AAB to always stay visible AxisAlignedBox aabInf; aabInf.setInfinite(); rect->setBoundingBox(aabInf);
Here is the port to MOGRE:
Copy to clipboard
// Create background material MaterialPtr material = MaterialManager.Singleton.Create("Background", "General"); material.GetTechnique(0).GetPass(0).CreateTextureUnitState("rockwall.tga"); material.GetTechnique(0).GetPass(0).DepthCheckEnabled = false; material.GetTechnique(0).GetPass(0).DepthWriteEnabled = false; material.GetTechnique(0).GetPass(0).LightingEnabled = false; // Create background rectangle covering the whole screen Rectangle2D rect = new Rectangle2D(true); rect.SetCorners(-1.0f, 1.0f, 1.0f, -1.0f); rect.SetMaterial("Background"); // Render the background before everything else rect.RenderQueueGroup = (byte)RenderQueueGroupID.RENDER_QUEUE_BACKGROUND; // Use infinite AAB to always stay visible AxisAlignedBox aab = new AxisAlignedBox(); aab.SetInfinite(); rect.BoundingBox = aab; // Attach background to the scene SceneNode node = mSmgr.RootSceneNode.CreateChildSceneNode("Background"); node.AttachObject(rect); // Example of background scrolling material.GetTechnique(0).GetPass(0).GetTextureUnitState(0).SetScrollAnimation(-0.25f, 0.0f);