The FBO class. More...
#include <VR3FBO.h>
Classes | |
| struct | ArrayElement |
| An element in the images array. More... | |
Public Member Functions | |
Constructor and Destructor | |
| VR3FBO (GLsizei width, GLsizei height) | |
| Constructor of the class. | |
| ~VR3FBO () | |
| Destructor of the class. | |
Start and Stop Functions | |
| void | Start () |
| Activates the Framebuffer Object. | |
Images Management Functions | |
| void | AddImage (int attachpoint, GLint internalformat, GLenum format, GLenum type) |
| Adds a new texture image to an attachment point. | |
| void | ActivateTexture (int attachpoint, unsigned int unit_id) |
| Activates a texture image on a specified texture unit. | |
| void | SetFiltering (int attachpoint, GLint min_filter, GLint mag_filter) |
| Activates a texture image on a specified texture unit. | |
Private Member Functions | |
| VR3FBO (const VR3FBO &) | |
| Disable default copy constructor. | |
| VR3FBO & | operator= (const VR3FBO &) |
| Disable default assignment operator. | |
Private Attributes | |
| GLuint | m_FBO |
| Framebuffer Object GL name. | |
| GLuint | m_depthRBO |
| Renderbuffer for depth component. | |
| ArrayElement | m_images [VR3FBO_MAX_IMAGES] |
| Texture images attached to every attachment point. | |
| GLsizei | m_width |
| Width of the FBO (shared among all images) | |
| GLsizei | m_height |
| Height of the FBO (shared among all images) | |
The FBO class.
FBO stands for Framebuffer Object, a Framebuffer Object represents something the GL is capable of rendering into. The default GL behaviour is to render objects to the default Framebuffer Object, which is the one associated with the GL window and cannot be manipulated by the user. This class is used to declare, initialize and eventually use a different Framebuffer Object for GL rendering. This is called off-screen rendering. The rendered data may be written on textures to be used later on for more rendering passes. Example usages of this solutions are:
A single FBO may be associated with many different images rendered at once while rendering to the FBO. Every single image is associated with a color attachment number. Up to a total of the minimum between the implementation-dependent constants GL_MAX_COLOR_ATTACHMENTS and GL_MAX_DRAW_BUFFERS images may be attached to a single FBO. When using the standard shaders, the only image rendered will be the one attached to GL_COLOR_ATTACHMENT0. When using a user-defined shader, output color fragColorX will be written to the image attached to GL_COLOR_ATTACHMENTX. The total number of color attachment will always be bounded to VR3FBO_MAX_IMAGES (implementation-independent constant). The Framebuffer Object is always provided with a depth component only Renderbuffer Object. This is necessary to enable depth comparison and proper scene rendering. Contents of the depth renderbuffer object cannot be used as a texture. If depth information is needed as a texture, the user is encorauged to write it on one of the available color attachments.
NOTE: While the default shaders may be used to render the scene to a user-defined Framebuffer Object, they are not capable to use the obtained texture images in any way. User-defined shaders must be used to work with the obtained images.
NOTE: The built-in shadow mapping method uses GL FBOs to implement the used EVSM algorithm, but this class is not used. Indeed, as previously noted, the default built-in shaders are not capable of accessing the texture images generated using this FBO class.
Definition at line 67 of file VR3FBO.h.
| VR3FBO::VR3FBO | ( | const VR3FBO & | ) | [private] |
Disable default copy constructor.
| VR3FBO::VR3FBO | ( | GLsizei | width, |
| GLsizei | height | ||
| ) |
Constructor of the class.
This function builds a ne VR3FBO object with no images attached to it, something must be attached to it in order to start using the FBO.
| [in] | width,height | Size of the FBO. |
| VR3FBO::~VR3FBO | ( | ) |
Destructor of the class.
Destroys the FBO and every texture images that was previously bound to the framebuffer object.
| void VR3FBO::ActivateTexture | ( | int | attachpoint, |
| unsigned int | unit_id | ||
| ) |
Activates a texture image on a specified texture unit.
Activates the texture image attached to the given attachpoint as the active texture (for shading) in unit unit_id. The unit_id meaning is the same we have in the VR3Texture::Activate() method.
| [in] | attachpoint | The desired color attachment point (integer value) |
| [in] | unit_id | The unit_id to bind the texture to (same as written in the sampler) |
| void VR3FBO::AddImage | ( | int | attachpoint, |
| GLint | internalformat, | ||
| GLenum | format, | ||
| GLenum | type | ||
| ) |
Adds a new texture image to an attachment point.
This method is used to add a new image to one of the available attachment points. An error will arise if the attachpoint parameter is not valid considering the maximum color attachments upper bound, or if the specified attachment point is already bounded to another texture image.
| [in] | attachpoint | The desired color attachment point (integer value) |
| [in] | internalformat | The new texture image internal format |
| [in] | format | The new texture image format |
| [in] | type | The new texture image data type |
| void VR3FBO::SetFiltering | ( | int | attachpoint, |
| GLint | min_filter, | ||
| GLint | mag_filter | ||
| ) |
Activates a texture image on a specified texture unit.
Sets the filtering method to use for the texture image attached to the specified attachment point. If GL_NEAREST_MIPMAP_NEAREST, GL_LINEAR_MIPMAP_NEAREST, GL_NEAREST_MIPMAP_LINEAR or GL_LINEAR_MIPMAP_LINEAR is specified as minification filter, mipmaps will automatically be generated when the texture image is activated with the VR3FBO::ActivateTexture() function.
| [in] | attachpoint | The desired color attachment point (integer value) |
| [in] | min_filter | The texture minification filter |
| [in] | mag_filter | The texture magnification filter |
| void VR3FBO::Start | ( | ) |
Activates the Framebuffer Object.
This method activates the framebuffer object. Each drawing operation executed after this call will be performed to this framebuffer. An error will arise if the framebuffer object is not complete. This function is called by the proper Begin() function and may not be called directly by the user.
GLuint VR3FBO::m_depthRBO [private] |
GLuint VR3FBO::m_FBO [private] |
GLsizei VR3FBO::m_height [private] |
ArrayElement VR3FBO::m_images[VR3FBO_MAX_IMAGES] [private] |
GLsizei VR3FBO::m_width [private] |
1.7.2
