Magnum::GL::BufferTexture class

Buffer texture.

Contents

This texture is, unlike classic textures such as Texture, used as simple data source, without any unnecessary interpolation and wrapping methods.

Usage

Texture data are stored in buffer and after binding the buffer to the texture using setBuffer(), you can fill the buffer at any time using data setting functions in Buffer itself.

Note that the buffer is not managed (e.g. deleted on destruction) by the texture, so you have to manage it on your own and ensure that it is available for whole texture lifetime. On the other hand it allows you to use one buffer for more textures or store more than one data in it.

Example usage:

GL::Buffer buffer;
GL::BufferTexture texture;
texture.setBuffer(GL::BufferTextureFormat::RGB32F, buffer);

Vector3 data[200]{
    // ...
};
buffer.setData(data, GL::BufferUsage::StaticDraw);

In shader, the texture is used via samplerBuffer, isamplerBuffer or usamplerBuffer. Unlike in classic textures, coordinates for buffer textures are integer coordinates passed to texelFetch(). See AbstractShaderProgram documentation for more information about usage in shaders.

Performance optimizations

If either ARB_direct_state_access (part of OpenGL 4.5) or EXT_direct_state_access is available, setBuffer() functions use DSA to avoid unnecessary calls to glActiveTexture() and glBindTexture(). See relevant section in AbstractTexture documentation and respective function documentation for more information.

Base classes

class AbstractTexture
Base for textures.

Public static functions

static auto maxSize() -> Int
Max supported buffer texture size.
static auto offsetAlignment() -> Int
Minimum required alignment for texture buffer offsets.
static auto wrap(GLuint id, ObjectFlags flags = {}) -> BufferTexture
Wrap existing OpenGL buffer texture object.

Constructors, destructors, conversion operators

BufferTexture() explicit
Constructor.
BufferTexture(NoCreateT) explicit noexcept
Construct without creating the underlying OpenGL object.

Public functions

void bindImage(Int imageUnit, ImageAccess access, ImageFormat format)
Bind texture to given image unit.
auto setBuffer(BufferTextureFormat internalFormat, Buffer& buffer) -> BufferTexture&
Set texture buffer.
auto setBuffer(BufferTextureFormat internalFormat, Buffer& buffer, GLintptr offset, GLsizeiptr size) -> BufferTexture&
Set texture buffer.

Function documentation

static Int Magnum::GL::BufferTexture::maxSize()

Max supported buffer texture size.

The result is cached, repeated queries don't result in repeated OpenGL calls. If ARB_texture_buffer_object (part of OpenGL 3.1) is not available, returns 0.

static Int Magnum::GL::BufferTexture::offsetAlignment()

Minimum required alignment for texture buffer offsets.

The result is cached, repeated queries don't result in repeated OpenGL calls. If extension ARB_texture_buffer_range (part of OpenGL 4.3) is not available, returns 1.

static BufferTexture Magnum::GL::BufferTexture::wrap(GLuint id, ObjectFlags flags = {})

Wrap existing OpenGL buffer texture object.

Parameters
id OpenGL buffer texture ID
flags Object creation flags

The id is expected to be of an existing OpenGL texture object with target GL_TEXTURE_BUFFER. Unlike texture created using constructor, the OpenGL object is by default not deleted on destruction, use flags for different behavior.

Magnum::GL::BufferTexture::BufferTexture() explicit

Constructor.

Creates new OpenGL texture object. If ARB_direct_state_access (part of OpenGL 4.5) is not available, the texture is created on first use.

Magnum::GL::BufferTexture::BufferTexture(NoCreateT) explicit noexcept

Construct without creating the underlying OpenGL object.

The constructed instance is equivalent to moved-from state. Useful in cases where you will overwrite the instance later anyway. Move another object over it to make it useful.

This function can be safely used for constructing (and later destructing) objects even without any OpenGL context being active.

void Magnum::GL::BufferTexture::bindImage(Int imageUnit, ImageAccess access, ImageFormat format)

Bind texture to given image unit.

Parameters
imageUnit Image unit
access Image access
format Image format

BufferTexture& Magnum::GL::BufferTexture::setBuffer(BufferTextureFormat internalFormat, Buffer& buffer)

Set texture buffer.

Parameters
internalFormat Internal format
buffer Buffer with data
Returns Reference to self (for method chaining)

Binds given buffer to this texture. The buffer itself can be then filled with data of proper format at any time using Buffer's own data setting functions. If neither ARB_direct_state_access (part of OpenGL 4.5) nor EXT_direct_state_access is available, the texture is bound before the operation (if not already).

BufferTexture& Magnum::GL::BufferTexture::setBuffer(BufferTextureFormat internalFormat, Buffer& buffer, GLintptr offset, GLsizeiptr size)

Set texture buffer.

Parameters
internalFormat Internal format
buffer Buffer
offset Offset
size Data size
Returns Reference to self (for method chaining)

Binds range of given buffer to this texture. The buffer itself can be then filled with data of proper format at any time using Buffer's own data setting functions. If neither ARB_direct_state_access (part of OpenGL 4.5) nor EXT_direct_state_access is available, the texture is bound before the operation (if not already).