OGRE-Next  3.0.0unstable
Object-Oriented Graphics Rendering Engine
Ogre::CompositorPassCompute Class Reference

Implementation of CompositorPass This implementation will render a fullscreen triangle/quad to the RenderTarget using the parameters from definition (rectangle area, whether triangle or quad pass, whether to include frustum corners, etc) More...

#include <OgreCompositorPassCompute.h>

+ Inheritance diagram for Ogre::CompositorPassCompute:

Public Member Functions

 CompositorPassCompute (const CompositorPassComputeDef *definition, Camera *defaultCamera, CompositorNode *parentNode, const RenderTargetViewDef *rtv)
 
 ~CompositorPassCompute () override
 
void execute (const Camera *lodCamera) override
 
- Public Member Functions inherited from Ogre::CompositorPass
 CompositorPass (const CompositorPassDef *definition, CompositorNode *parentNode)
 
virtual ~CompositorPass ()
 
ResourceTransitionArray_getResourceTransitionsNonConst ()
 
virtual void analyzeBarriers (const bool bClearBarriers=true)
 Bakes all of the memory barriers / resource transition that will be needed before executing a GPU command like rendering, copying/blit or compute. More...
 
Vector2 getActualDimensions () const
 
const CompositorPassDefgetDefinition () const
 
const CompositorNodegetParentNode () const
 
RenderPassDescriptorgetRenderPassDesc () const
 
const ResourceTransitionArraygetResourceTransitions () const
 
const CompositorTextureVecgetTextureDependencies () const
 
CompositorPassType getType () const
 
Real getViewportAspectRatio (size_t vpIdx)
 
virtual void notifyCleared ()
 
virtual void notifyDestroyed (const UavBufferPacked *buffer)
 
virtual void notifyDestroyed (TextureGpu *channel)
 
virtual bool notifyRecreated (const TextureGpu *channel)
 
virtual void notifyRecreated (const UavBufferPacked *oldBuffer, UavBufferPacked *newBuffer)
 
void profilingBegin ()
 
void profilingEnd ()
 
virtual void resetNumPassesLeft ()
 

Detailed Description

Implementation of CompositorPass This implementation will render a fullscreen triangle/quad to the RenderTarget using the parameters from definition (rectangle area, whether triangle or quad pass, whether to include frustum corners, etc)

A fullscreen quad are two triangles that form a rectangle, which cover the entire screen. This is however an inefficient way of harnessing the GPU's power. Modern GPUs iterate a whole bounding rect that encloses each triangle (it's highly more parallelizable & scalable than the scanline algorithm used by older Voodoo cards in the 90's). That means we're wasting 50% of GPU reasources in pixels that aren't drawn.
A much faster approach made famous by Emil Persson (see max area triangulation http://www.humus.name/index.php?page=News&ID=228) is to render a single oversized triangle that covers the entire screen, which has it's UV scaled up; so that when interpolated at screen position, it appears it goes from the range [0; 1) like a regular quad pass. The difference is that pixels that go past the viewport are much better clipped/earlied-out by the GPU than those that fall inside the viewport but outside the triangle (like the rectangle approach)
This faster technique only works for passes that cover the entire screen. When the viewport is not 0 0 1 1; the CompositorPassCompute automatically switches to a fullscreen quad.
IMPORTANT: The texel-to-pixel adjustment offset is included in the world matrix passed to the vertex shader. This differs from Ogre 1.x which tried to embed the offset into the vertices.
IMPORTANT: When the viewport is not 0 0 1 1; the scale & position factors are passed through the world matrix. This behavior differs from Ogre 1.x
Author
Matias N. Goldberg
Version
1.0

Constructor & Destructor Documentation

◆ CompositorPassCompute()

Ogre::CompositorPassCompute::CompositorPassCompute ( const CompositorPassComputeDef definition,
Camera defaultCamera,
CompositorNode parentNode,
const RenderTargetViewDef rtv 
)

◆ ~CompositorPassCompute()

Ogre::CompositorPassCompute::~CompositorPassCompute ( )
override

Member Function Documentation

◆ execute()

void Ogre::CompositorPassCompute::execute ( const Camera lodCamera)
overridevirtual

Implements Ogre::CompositorPass.


The documentation for this class was generated from the following file: