---

NSOpenGLPixelBuffer Class Reference

Overview

The NSOpenGLPixelBuffer class gives Cocoa OpenGL implementations access to accelerated offscreen rendering. With this offscreen rendering you could, for instance, draw into the pixel buffer, then use the contents as a texture map elsewhere. Typically you initialize an NSOpenGLPixelBuffer object using the initWithTextureTarget:textureInternalFormat:textureMaxMipMapLevel:pixelsWide:pixelsHigh: method and attach the resulting object to an OpenGL context with the setPixelBuffer:cubeMapFace:mipMapLevel:currentVirtualScreen: method of NSOpenGLContext.

Tasks

Initializing an OpenGL Pixel Buffer

• – initWithTextureTarget:textureInternalFormat:textureMaxMipMapLevel:pixelsWide:pixelsHigh:

Obtaining Information About an OpenGL Pixel Buffer

• – pixelsHigh
• – pixelsWide
• – textureInternalFormat
• – textureMaxMipMapLevel
• – textureTarget

Instance Methods

initWithTextureTarget:textureInternalFormat:textureMaxMipMapLevel:pixelsWide:pixelsHigh:

Returns an NSOpenGLPixelBuffer object initialized with the specified parameters.

- (id)initWithTextureTarget:(GLenum)target textureInternalFormat:(GLenum)format textureMaxMipMapLevel:(GLint)maxLevel pixelsWide:(GLsizei)pixelsWide pixelsHigh:(GLsizei)pixelsHigh

Parameters

target

The texture object. This value should be one of the following: GL_TEXTURE_2D,GL_TEXTURE_CUBE_MAP, or GL_TEXTURE_RECTANGLE_EXT.

format

The base internal format of the texture. This value should be GL_RGB, GL_RGBA, or GL_DEPTH_COMPONENT.

maxLevel

The desired maximum mipmap level of the structure, starting with zero.

pixelsWide

The width of the texture (in pixels) in the pixel buffer.

pixelsHigh

The height of the texture (in pixels) in the pixel buffer.

Return Value

An initialized NSOpenGLPixelBuffer object or nil if the initialization failed. Initialization can fail if there is inconsistency among the parameter values. See the OpenGL documentation for glTexImage2D for more information.

Discussion

The value you pass to the target parameter defines several other constraints that are then applied to the remaining parameters. The list below gives the values you can pass to target and the additional constraints.

• GL_TEXTURE_2D

• GL_TEXTURE_CUBE_MAP - the values in pixelsWide and pixelsHigh must be equal.

• GL_TEXTURE_RECTANGLE_EXT - maxLevel must be zero.

Normally, when using the GL_TEXTURE_2D and GL_TEXTURE_CUBE_MAP targets, you must specify width and height values that are powers of two. When the ARB_texture_non_power_of_two extension is present, however, some types of hardware can support values that are not powers of two. You should check for the presence of this extension before specifying non power-of-two values.

If the texture map cannot be created, you can use the glGetError function to get the error code.

Availability

• Available in Mac OS X v10.3 and later.

Related Sample Code

• Quartz Composer Offline Rendering
• Quartz Composer Texture

Declared In

NSOpenGL.h

pixelsHigh

Returns the height of the receiver’s texture (in pixels).

- (GLsizei)pixelsHigh

Return Value

The height of the texture (in pixels).

Availability

• Available in Mac OS X v10.3 and later.

See Also

• – pixelsWide

Declared In

NSOpenGL.h

pixelsWide

Returns the width of the receiver’s texture (in pixels).

- (GLsizei)pixelsWide

Return Value

The width of the texture (in pixels).

Availability

• Available in Mac OS X v10.3 and later.

See Also

• – pixelsHigh

Declared In

NSOpenGL.h

textureInternalFormat

Returns the internal format of the receiver’s texture.

- (GLenum)textureInternalFormat

Return Value

The texture format, which can be one of the following values: GL_RGB, GL_RGBA, or GL_DEPTH_COMPONENT.

Availability

• Available in Mac OS X v10.3 and later.

Declared In

NSOpenGL.h

textureMaxMipMapLevel

Returns the maximum mipmap level of the receiver’s texture.

- (GLint)textureMaxMipMapLevel

Return Value

The maximum mipmap level.

Availability

• Available in Mac OS X v10.3 and later.

Declared In

NSOpenGL.h

textureTarget

Returns the texture target of the receiver.

- (GLenum)textureTarget

Return Value

The texture target, which can be one of the following values: GL_TEXTURE_2D, GL_TEXTURE_CUBE_MAP, or GL_TEXTURE_RECTANGLE_EXT.

Availability

• Available in Mac OS X v10.3 and later.

Declared In

NSOpenGL.h

---