WSGLScreenSpaceAmbientOcclusion Class Reference

Class for using Screen Space Ambient Occlusion (SSAO) within an OpenGL renderer. More...

#include <Rendering/OpenGL/wsglscreenspaceambientocclusion.h>

Inherits QObject.

Signals
void	reinitRequested ()

Public Member Functions
	WSGLScreenSpaceAmbientOcclusion ()
	~WSGLScreenSpaceAmbientOcclusion () override
GLfloat	getAttenuation () const
GLfloat	getEdgeSize ()
unsigned	getNumSamples () const
GLfloat	getSampleLength () const
bool	getSsaoSupported () const
GLfloat	getStrength () const
bool	initialize (WSGLContext &context)
bool	renderLayersWithSsao (GLuint fbo, const Camera &camera, const Mesh::BoundingBox &sceneExtent, const Mesh::TransformMatrix &matWorldViewProj, WSGLBufferObjectCacheItemPtr &vboSquareVerts, WSGLBufferObjectCacheItemPtr &vboSquareElem, WSGLLayers &screenLayers, WSGLTexture &colorTexture, WSGLTexture *specularTexture)
bool	resize ()
void	setAdjust (GLfloat x, GLfloat y)
void	setAttenuation (GLfloat f)
void	setBackgroundColor (const QColor &color)
void	setNumSamples (unsigned i)
void	setSampleLength (GLfloat f)
void	setSize (int viewportWidth, int viewportHeight)
void	setSpecularHighlighting (bool b)
void	setStrength (GLfloat f)

Detailed Description

SSAO is a shadowing technique used to make depth more perceptible within a scene. SSAO is expensive, so it is recommended it only be activated:

-   If the user has not disabled it in an attempt to improve performance.

All data will be stored as pixel unpack buffers in the WSGLBufferObjectCache provided by the caller.

See also

WSGLBufferObjectCache

To add the SSAO capability to a new shader, follow these steps:

1.  Add the capability to the shader's implementation.
2.  Add the required code to the shader:

    2a. If the shader doesn't use specular highlighting (eg. Blinn-Phong)
        replace "gl_FragColor = ..." with:

            if (wsgl_uScreenSpaceAmbientOcclusionEnabled)
                wsgl_ScreenSpaceAmbientOcclusionSpecular(normal, color.a, gl_FragCoord.z);
            gl_FragData[0] = color;

    2b. If the shader does use specular highlighting (eg. Blinn-Phong)
        replace "gl_FragColor = ..." with:

            if (wsgl_uScreenSpaceAmbientOcclusionEnabled)
            {
                color = Color without specular highlights;
                vec4 specular = only specular highlights;
                wsgl_ScreenSpaceAmbientOcclusionSpecular(normal, color.a, gl_FragCoord.z, specular);
            }
            else
                color = Color with specular highlighting;
            gl_FragData[0] = color;

3.  Replace the virtual shader function 'bool appliesScreenSpaceAmbientOcclusion' so
    it always returns true.
4.  If the shader applies specular lighting, replace the virtual shader function
    'bool appliesSpecular' to return true.

The SSAO currently supports:

-   Depth Peeling
-   Specular Highlighting
-   Transparent objects (Alpha Blending)

The SSAO current doesn't support:

-   Half resolution
-   Window edge clipping

Constructor & Destructor Documentation

WSGLScreenSpaceAmbientOcclusion()

WSGLScreenSpaceAmbientOcclusion

(

)

~WSGLScreenSpaceAmbientOcclusion()

~WSGLScreenSpaceAmbientOcclusion ( )

override

Member Function Documentation

getAttenuation()

GLfloat getAttenuation

(

)

const

getEdgeSize()

GLfloat getEdgeSize

(

)

getNumSamples()

unsigned getNumSamples

(

)

const

getSampleLength()

GLfloat getSampleLength

(

)

const

getSsaoSupported()

bool getSsaoSupported

(

)

const

getStrength()

GLfloat getStrength

(

)

const

initialize()

bool initialize

(

WSGLContext &

context

)

reinitRequested

void reinitRequested ( )

signal

renderLayersWithSsao()

bool renderLayersWithSsao	(	GLuint	fbo,
		const Camera &	camera,
		const Mesh::BoundingBox &	sceneExtent,
		const Mesh::TransformMatrix &	matWorldViewProj,
		WSGLBufferObjectCacheItemPtr &	vboSquareVerts,
		WSGLBufferObjectCacheItemPtr &	vboSquareElem,
		WSGLLayers &	screenLayers,
		WSGLTexture &	colorTexture,
		WSGLTexture *	specularTexture
	)

resize()

bool resize

(

)

setAdjust()

void setAdjust	(	GLfloat	x,
		GLfloat	y
	)

setAttenuation()

void setAttenuation

(

GLfloat

f

)

setBackgroundColor()

void setBackgroundColor

(

const QColor &

color

)

setNumSamples()

void setNumSamples

(

unsigned

i

)

setSampleLength()

void setSampleLength

(

GLfloat

f

)

setSize()

void setSize	(	int	viewportWidth,
		int	viewportHeight
	)

setSpecularHighlighting()

void setSpecularHighlighting

(

bool

b

)

setStrength()

void setStrength

(

GLfloat

f

)