SLGLFbo Class Reference

Wrapper around an OpenGL framebuffer object for offscreen rendering. More...

#include <SLGLFbo.h>

Public Member Functions
	SLGLFbo (SLuint w, SLuint h, SLenum magFilter=GL_NEAREST, SLenum minFilter=GL_NEAREST, SLint internalFormat=GL_RGB16F, SLint format=GL_FLOAT, SLint wrap=GL_REPEAT)
	Creates the framebuffer, its colour texture and its depth renderbuffer. More...
	~SLGLFbo ()
	Deletes the texture, the renderbuffer and the framebuffer. More...
void	activateAsTexture (int progId, const SLstring &samplerName, int textureUnit=0)
	Binds the colour texture to a texture unit and sets the sampler uniform. More...

Public Attributes
SLuint	width
	Width of the framebuffer in pixels. More...
SLuint	height
	Height of the framebuffer in pixels. More...
SLuint	attachment
SLuint	fboID
	GL id of the framebuffer object. More...
SLuint	texID
	GL id of the colour attachment texture. More...
SLuint	rboID
	GL id of the depth renderbuffer. More...

Detailed Description

Wrapper around an OpenGL framebuffer object for offscreen rendering.

An SLGLFbo owns three GL objects: a framebuffer, a 2D colour texture bound to GL_COLOR_ATTACHMENT0, and a renderbuffer holding a 24 bit depth buffer. Rendering into it and then binding the result as a texture is the usual way to implement a post-processing or reflection pass.

Warning

The constructor issues OpenGL calls, so an instance may only be created on the main thread once a GL context exists — unlike the mesh classes, it cannot be built during asynchronous asset loading.

Definition at line 26 of file SLGLFbo.h.

Constructor & Destructor Documentation

SLGLFbo()

SLGLFbo::SLGLFbo	(	SLuint	w,
		SLuint	h,
		SLenum	magFilter = GL_NEAREST,
		SLenum	minFilter = GL_NEAREST,
		SLint	internalFormat = GL_RGB16F,
		SLint	format = GL_FLOAT,
		SLint	wrap = GL_REPEAT
	)

Creates the framebuffer, its colour texture and its depth renderbuffer.

Parameters

w	Width in pixels
h	Height in pixels
magFilter	GL magnification filter of the colour texture
minFilter	GL minification filter of the colour texture
internalFormat	GL internal format of the colour texture
format	GL data type of the colour texture pixels
wrap	GL wrap mode applied to both S and T The previously bound framebuffer is restored before returning. A completeness failure is reported on stderr, not thrown.

Definition at line 15 of file SLGLFbo.cpp.

                              : width(w), height(h)
{
    GLint previousFrameBuffer;
    glGetIntegerv(GL_FRAMEBUFFER_BINDING, &previousFrameBuffer);
 
    // Init framebuffer.
    glGenFramebuffers(1, &fboID);
    glBindFramebuffer(GL_FRAMEBUFFER, fboID);
 
    glGenTextures(1, &texID);
    glBindTexture(GL_TEXTURE_2D, texID);
 
    // Texture parameters.
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, minFilter);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, magFilter);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrap);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrap);
 
    glTexImage2D(GL_TEXTURE_2D,
                 0,
                 internalFormat,
                 w,
                 h,
                 0,
                 GL_RGBA,
                 format,
                 nullptr);
 
    glFramebufferTexture2D(GL_FRAMEBUFFER,
                           GL_COLOR_ATTACHMENT0,
                           GL_TEXTURE_2D,
                           texID,
                           0);
 
    glGenRenderbuffers(1, &rboID);
    glBindRenderbuffer(GL_RENDERBUFFER, rboID);
 
    // Use a single rbo for both depth and stencil buffer
    glRenderbufferStorage(GL_RENDERBUFFER,
                          GL_DEPTH_COMPONENT24,
                          w,
                          h);
 
    glFramebufferRenderbuffer(GL_FRAMEBUFFER,
                              GL_DEPTH_ATTACHMENT,
                              GL_RENDERBUFFER,
                              rboID);
 
    glBindRenderbuffer(GL_RENDERBUFFER, 0);
    glBindFramebuffer(GL_FRAMEBUFFER,
                      previousFrameBuffer);
 
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        std::cerr << "FBO failed to initialize correctly." << std::endl;
}

~SLGLFbo()

SLGLFbo::~SLGLFbo

(

)

Deletes the texture, the renderbuffer and the framebuffer.

Definition at line 77 of file SLGLFbo.cpp.

{
    glDeleteTextures(1, &texID);
    glDeleteFramebuffers(1, &fboID);
}

Member Function Documentation

activateAsTexture()

void SLGLFbo::activateAsTexture	(	int	progId,
		const SLstring &	samplerName,
		int	textureUnit = 0
	)

Binds the colour texture to a texture unit and sets the sampler uniform.

Parameters

progId	GL id of the shader program holding the sampler
samplerName	Name of the sampler uniform in that program
textureUnit	Texture unit to bind to, added to GL_TEXTURE0

Definition at line 83 of file SLGLFbo.cpp.

{
    glActiveTexture(GL_TEXTURE0 + textureUnit);
    glBindTexture(GL_TEXTURE_2D, texID);
    glUniform1i(glGetUniformLocation(progId,
                                     glSamplerName.c_str()),
                textureUnit);
}

Member Data Documentation

attachment

SLuint SLGLFbo::attachment

Deprecated:

Never assigned or read; left uninitialised

Definition at line 60 of file SLGLFbo.h.

fboID

SLuint SLGLFbo::fboID

GL id of the framebuffer object.

Definition at line 61 of file SLGLFbo.h.

height

SLuint SLGLFbo::height

Height of the framebuffer in pixels.

Definition at line 59 of file SLGLFbo.h.

rboID

SLuint SLGLFbo::rboID

GL id of the depth renderbuffer.

Definition at line 63 of file SLGLFbo.h.

texID

SLuint SLGLFbo::texID

GL id of the colour attachment texture.

Definition at line 62 of file SLGLFbo.h.

width

SLuint SLGLFbo::width

Width of the framebuffer in pixels.

Definition at line 58 of file SLGLFbo.h.

---

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

• SLGLFbo.h
• SLGLFbo.cpp