From 393b5cd1dc438872af89d334ef6e5fcc59f27d47 Mon Sep 17 00:00:00 2001 From: David Walter Seikel Date: Sun, 13 Jan 2013 17:24:39 +1000 Subject: Added Irrlicht 1.8, but without all the Windows binaries. --- .../examples/26.OcclusionQuery/main.cpp | 213 +++++++++++++++++++++ 1 file changed, 213 insertions(+) create mode 100644 libraries/irrlicht-1.8/examples/26.OcclusionQuery/main.cpp (limited to 'libraries/irrlicht-1.8/examples/26.OcclusionQuery/main.cpp') diff --git a/libraries/irrlicht-1.8/examples/26.OcclusionQuery/main.cpp b/libraries/irrlicht-1.8/examples/26.OcclusionQuery/main.cpp new file mode 100644 index 0000000..17f64b2 --- /dev/null +++ b/libraries/irrlicht-1.8/examples/26.OcclusionQuery/main.cpp @@ -0,0 +1,213 @@ +/** Example 026 OcclusionQuery + +This Tutorial shows how to speed up rendering by use of the +OcclusionQuery feature. The usual rendering tries to avoid rendering of +scene nodes by culling those nodes which are outside the visible area, the +view frustum. However, this technique does not cope with occluded objects +which are still in the line of sight, but occluded by some larger object +between the object and the eye (camera). Occlusion queries check exactly that. +The queries basically measure the number of pixels that a previous render +left on the screen. +Since those pixels cannot be recognized at the end of a rendering anymore, +the pixel count is measured directly when rendering. Thus, one needs to render +the occluder (the object in front) first. This object needs to write to the +z-buffer in order to become a real occluder. Then the node is rendered and in +case a z-pass happens, i.e. the pixel is written to the framebuffer, the pixel +is counted in the query. +The result of a query is the number of pixels which got through. One can, based +on this number, judge if the scene node is visible enough to be rendered, or if +the node should be removed in the next round. Also note that the number of +pixels is a safe over approximation in general. The pixels might be overdrawn +later on, and the GPU tries to avoid inaccuracies which could lead to false +negatives in the queries. + +As you might have recognized already, we had to render the node to get the +numbers. So where's the benefit, you might say. There are several ways where +occlusion queries can help. It is often a good idea to just render the bbox +of the node instead of the actual mesh. This is really fast and is a safe over +approximation. If you need a more exact render with the actual geometry, it's +a good idea to render with just basic solid material. Avoid complex shaders +and state changes through textures. There's no need while just doing the +occlusion query. At least if the render is not used for the actual scene. This +is the third way to optimize occlusion queries. Just check the queries every +5th or 10th frame, or even less frequent. This depends on the movement speed +of the objects and camera. +*/ + +#ifdef _MSC_VER +// We'll also define this to stop MSVC complaining about sprintf(). +#define _CRT_SECURE_NO_WARNINGS +#pragma comment(lib, "Irrlicht.lib") +#endif + +#include +#include "driverChoice.h" + +using namespace irr; + +/* +We need keyboard input events to switch some parameters +*/ +class MyEventReceiver : public IEventReceiver +{ +public: + // This is the one method that we have to implement + virtual bool OnEvent(const SEvent& event) + { + // Remember whether each key is down or up + if (event.EventType == irr::EET_KEY_INPUT_EVENT) + KeyIsDown[event.KeyInput.Key] = event.KeyInput.PressedDown; + + return false; + } + + // This is used to check whether a key is being held down + virtual bool IsKeyDown(EKEY_CODE keyCode) const + { + return KeyIsDown[keyCode]; + } + + MyEventReceiver() + { + for (u32 i=0; i(640, 480), 16, false, false, false, &receiver); + + if (device == 0) + return 1; // could not create selected driver. + + video::IVideoDriver* driver = device->getVideoDriver(); + scene::ISceneManager* smgr = device->getSceneManager(); + + smgr->getGUIEnvironment()->addStaticText(L"Press Space to hide occluder.", core::recti(10,10, 200,50)); + + /* + Create the node to be occluded. We create a sphere node with high poly count. + */ + scene::ISceneNode * node = smgr->addSphereSceneNode(10, 64); + if (node) + { + node->setPosition(core::vector3df(0,0,60)); + node->setMaterialTexture(0, driver->getTexture("../../media/wall.bmp")); + node->setMaterialFlag(video::EMF_LIGHTING, false); + } + + /* + Now we create another node, the occluder. It's a simple plane. + */ + scene::ISceneNode* plane = smgr->addMeshSceneNode(smgr->addHillPlaneMesh( + "plane", core::dimension2df(10,10), core::dimension2du(2,2)), 0, -1, + core::vector3df(0,0,20), core::vector3df(270,0,0)); + + if (plane) + { + plane->setMaterialTexture(0, driver->getTexture("../../media/t351sml.jpg")); + plane->setMaterialFlag(video::EMF_LIGHTING, false); + plane->setMaterialFlag(video::EMF_BACK_FACE_CULLING, true); + } + + /* + Here we create the occlusion query. Because we don't have a plain mesh scene node + (ESNT_MESH or ESNT_ANIMATED_MESH), we pass the base geometry as well. Instead, + we could also pass a simpler mesh or the bounding box. But we will use a time + based method, where the occlusion query renders to the frame buffer and in case + of success (occlusion), the mesh is not drawn for several frames. + */ + driver->addOcclusionQuery(node, ((scene::IMeshSceneNode*)node)->getMesh()); + + /* + We have done everything, just a camera and draw it. We also write the + current frames per second and the name of the driver to the caption of the + window to examine the render speedup. + We also store the time for measuring the time since the last occlusion query ran + and store whether the node should be visible in the next frames. + */ + smgr->addCameraSceneNode(); + int lastFPS = -1; + u32 timeNow = device->getTimer()->getTime(); + bool nodeVisible=true; + + while(device->run()) + { + plane->setVisible(!receiver.IsKeyDown(irr::KEY_SPACE)); + + driver->beginScene(true, true, video::SColor(255,113,113,133)); + /* + First, we draw the scene, possibly without the occluded element. This is necessary + because we need the occluder to be drawn first. You can also use several scene + managers to collect a number of possible occluders in a separately rendered + scene. + */ + node->setVisible(nodeVisible); + smgr->drawAll(); + smgr->getGUIEnvironment()->drawAll(); + + /* + Once in a while, here every 100 ms, we check the visibility. We run the queries, + update the pixel value, and query the result. Since we already rendered the node + we render the query invisible. The update is made blocking, as we need the result + immediately. If you don't need the result immediately, e.g. because you have other + things to render, you can call the update non-blocking. This gives the GPU more + time to pass back the results without flushing the render pipeline. + If the update was called non-blocking, the result from getOcclusionQueryResult is + either the previous value, or 0xffffffff if no value has been generated at all, yet. + The result is taken immediately as visibility flag for the node. + */ + if (device->getTimer()->getTime()-timeNow>100) + { + driver->runAllOcclusionQueries(false); + driver->updateAllOcclusionQueries(); + nodeVisible=driver->getOcclusionQueryResult(node)>0; + timeNow=device->getTimer()->getTime(); + } + + driver->endScene(); + + int fps = driver->getFPS(); + + if (lastFPS != fps) + { + core::stringw tmp(L"OcclusionQuery Example ["); + tmp += driver->getName(); + tmp += L"] fps: "; + tmp += fps; + + device->setWindowCaption(tmp.c_str()); + lastFPS = fps; + } + } + + /* + In the end, delete the Irrlicht device. + */ + device->drop(); + + return 0; +} + +/* +That's it. Compile and play around with the program. +**/ -- cgit v1.1