Class encapsulating an OpenGL texture object. More...

#include <texture.hpp>

Public Member Functions
	texture ()
	Default constructor. More...

GLuint	name () const
	Retrieve the OpenGL name of this texture. More...

GLsizei	width () const
	Retrieve the width of the level 0 image of the allocated texture storage. More...

GLsizei	height () const
	Retrieve the height of the level 0 image of the allocated texture storage. More...

GLsizei	depth () const
	Retrieve the depth of the level 0 image of the allocated texture storage. More...

void	bind ()
	Bind this texture to its target. More...

void	parameter (GLenum pname, GLfloat param)
	Set a texture parameter. More...

void	parameter (GLenum pname, GLint param)
	Set a texture parameter. More...

void	parameter (GLenum pname, const GLfloat *param)
	Set a texture parameter. More...

void	parameter (GLenum pname, const GLint *param)
	Set a texture parameter. More...

template<typename T >
void	image_1d (GLint level, GLint internal_format, T the_width, GLenum format, GLenum type, const GLvoid *data)
	Allocate storage for a 1D image and upload texture data. More...

template<typename T , typename U >
void	image_2d (GLint level, GLint internal_format, T the_width, U the_height, GLenum format, GLenum type, const GLvoid *data)
	Allocate storage for a 2D image and upload texture data. More...

template<typename T , typename U , typename V >
void	image_3d (GLint level, GLint internal_format, T the_width, U the_height, V the_depth, GLenum format, GLenum type, const GLvoid *data)
	Allocate storage for a 3D image and upload texture data. More...

template<typename T , typename U >
void	sub_image_1d (GLint level, T xoffset, U the_width, GLenum format, GLenum type, const GLvoid *data)
	Update a section of a 1D image within the texture. More...

template<typename T , typename U , typename V , typename W >
void	sub_image_2d (GLint level, T xoffset, U yoffset, V the_width, W the_height, GLenum format, GLenum type, const GLvoid *data)
	Update a section of a 2D image within the texture. More...

template<typename T , typename U , typename V , typename W , typename X , typename Y >
void	sub_image_3d (GLint level, T xoffset, U yoffset, V zoffset, W the_width, X the_height, Y the_depth, GLenum format, GLenum type, const GLvoid *data)
	Update a section of a 3D image within the texture. More...

void	get_image (GLint level, GLint format, GLenum type, GLvoid *img)
	Get image data from this texture. More...

void	generate_mipmap ()
	Generate mipmaps for this texture. More...

Static Public Member Functions
static void	unbind ()
	Unbind the current texture from the target. More...

Detailed Description

template<GLenum Target = GL_TEXTURE_2D>
class gls::texture< Target >

Class encapsulating an OpenGL texture object.

A gls::texture is an object that encapsulates an OpenGL texture object.

Template Parameters

Target The target this buffer object will be bound to when calling bind()

Like all objects in GLS, the underlying name is generated at object construction and deleted at destruction. This can be retrieved with name().

Texture objects store arbitrary image data within server (GPU) memory. This data can then be used by shader samplers to e.g. provide texturing to rendered primitives.

Texture objects can contain multiple images. Each image is simply a block of data with an internal format. Typically, when uploading texture data to apply to a primitive, one uploads it as the level 0 image of the texture. In order to reduce aliasing effects that might occur when sampling from them, multiple smaller versions of the level 0 image can be created. This is what is known as a mipmap chain. OpenGL can automatically generate the mipmap chain for you from your level 0 data when you call the generate_mipmap() method. The algorithm used is implementation specific. Alternatively, you can manually upload each level yourself if you wish to.

In addition to the data, each texture object has certain parameters associated with it. These can control a multitude of different things. Parameters that are automatically set for you on creation of a gls::texture are GL_TEXTURE_MIN_FILTER and GL_TEXTURE_MAG_FILTER. They are both set to GL_LINEAR by default, meaning OpenGL uses bilinear filtering when sampling from the texture. If you generate mipmaps, those parameters should be set to take them into account. Other common parameters include those that control how the texture is tiled or clamped when the sampler is passed certain texture coordinates in the shader.

To use a gls::texture, simply call bind(). It will bind the gls::texture to its target binding and replace any previously bound to that target. To clear the binding to that target, call unbind(). In newer OpenGL, textures are bound to texture units which are in turn used by the samplers within a shader to access texel data within them. The number of available texture units depends on the hardware.

Example usage:

auto texture = gls::texture<GL_TEXTURE_2D>();
auto texture_data = std::vector<GLubyte>{ 255, 0, 0, 255, 0, 255, 0, 255, 0, 0, 255, 255 };
texture.image_2d( 0, GL_RGBA, 3, 1, GL_RGBA, GL_UNSIGNED_BYTE, texture_data.data() );
texture.generate_mipmap();
// Disable filtering
texture.parameter( GL_TEXTURE_MIN_FILTER, GL_NEAREST );
texture.parameter( GL_TEXTURE_MAG_FILTER, GL_NEAREST );
glActiveTexture( GL_TEXTURE0 );
texture.bind();
glActiveTexture( GL_TEXTURE0 + 1 );
... bind some other texture ...
... render some stuff using the textures ...
glActiveTexture( GL_TEXTURE0 );
texture.unbind();
glActiveTexture( GL_TEXTURE0 + 1 );
...

Constructor & Destructor Documentation

texture ( )

Default constructor.

The constructor, after a name has been generated for the object, sets the GL_TEXTURE_MIN_FILTER and GL_TEXTURE_MAG_FILTER texture parameters to GL_LINEAR.

texture ( int )

protected

Constructor that doesn't set texture parameters.

Currently only used internally by gls::buffertexture.

Member Function Documentation

GLuint name ( ) const

Retrieve the OpenGL name of this texture.

Returns: OpenGL name of this texture

GLsizei width ( ) const

Retrieve the width of the level 0 image of the allocated texture storage.

Returns: Width of the level 0 image of the allocated texture storage

GLsizei height ( ) const

Retrieve the height of the level 0 image of the allocated texture storage.

Returns: Height of the level 0 image of the allocated texture storage

GLsizei depth ( ) const

Retrieve the depth of the level 0 image of the allocated texture storage.

Returns: Depth of the level 0 image of the allocated texture storage

void bind ( )

Bind this texture to its target.

Bind this texture to the target specified by the Target template parameter. This replaces any previous binding on that target.

static void unbind ( )

static

Unbind the current texture from the target.

Unbind the texture currently bound to the target specified by the Target template parameter.

void parameter	(	GLenum	pname,
		GLfloat	param
	)

Set a texture parameter.

Set the given parameter to the given value

Parameters

pname	Name of the parameter to set
param	Value to set the parameter to

void parameter	(	GLenum	pname,
		GLint	param
	)

Set a texture parameter.

Set the given parameter to the given value

Parameters

pname	Name of the parameter to set
param	Value to set the parameter to

void parameter	(	GLenum	pname,
		const GLfloat *	param
	)

Set a texture parameter.

Set the given parameter to the given value

Parameters

pname	Name of the parameter to set
param	Pointer to the value to set the parameter to

void parameter	(	GLenum	pname,
		const GLint *	param
	)

Set a texture parameter.

Set the given parameter to the given value

Parameters

pname	Name of the parameter to set
param	Pointer to the value to set the parameter to

void image_1d	(	GLint	level,
		GLint	internal_format,
		T	the_width,
		GLenum	format,
		GLenum	type,
		const GLvoid *	data
	)

Allocate storage for a 1D image and upload texture data.

This marks any previously allocated image storage for deletion by the GL.

Parameters

level	The level of detail number, 0 is the base image, level n is the n-th mipmap
internal_format	Internal format of the texture
the_width	Width of the texture image
format	Format of the data passed to this method
type	Type of the data passed to this method
data	Pointer to memory containing the data to upload

void image_2d	(	GLint	level,
		GLint	internal_format,
		T	the_width,
		U	the_height,
		GLenum	format,
		GLenum	type,
		const GLvoid *	data
	)

Allocate storage for a 2D image and upload texture data.

This marks any previously allocated image storage for deletion by the GL.

Parameters

level	The level of detail number, 0 is the base image, level n is the n-th mipmap
internal_format	Internal format of the texture
the_width	Width of the texture image
the_height	Height of the texture image
format	Format of the data passed to this method
type	Type of the data passed to this method
data	Pointer to memory containing the data to upload

void image_3d	(	GLint	level,
		GLint	internal_format,
		T	the_width,
		U	the_height,
		V	the_depth,
		GLenum	format,
		GLenum	type,
		const GLvoid *	data
	)

Allocate storage for a 3D image and upload texture data.

This marks any previously allocated image storage for deletion by the GL.

Parameters

level	The level of detail number, 0 is the base image, level n is the n-th mipmap
internal_format	Internal format of the texture
the_width	Width of the texture image
the_height	Height of the texture image
the_depth	Depth of the texture image
format	Format of the data passed to this method
type	Type of the data passed to this method
data	Pointer to memory containing the data to upload

void sub_image_1d	(	GLint	level,
		T	xoffset,
		U	the_width,
		GLenum	format,
		GLenum	type,
		const GLvoid *	data
	)

Update a section of a 1D image within the texture.

Parameters

level	The level of detail number, 0 is the base image, level n is the n-th mipmap
xoffset	x-offset of the region to update
the_width	Width of the region to update
format	Format of the data passed to this method
type	Type of the data passed to this method
data	Pointer to memory containing the data to upload

void sub_image_2d	(	GLint	level,
		T	xoffset,
		U	yoffset,
		V	the_width,
		W	the_height,
		GLenum	format,
		GLenum	type,
		const GLvoid *	data
	)

Update a section of a 2D image within the texture.

Parameters

level	The level of detail number, 0 is the base image, level n is the n-th mipmap
xoffset	x-offset of the region to update
yoffset	y-offset of the region to update
the_width	Width of the region to update
the_height	Height of the region to update
format	Format of the data passed to this method
type	Type of the data passed to this method
data	Pointer to memory containing the data to upload

void sub_image_3d	(	GLint	level,
		T	xoffset,
		U	yoffset,
		V	zoffset,
		W	the_width,
		X	the_height,
		Y	the_depth,
		GLenum	format,
		GLenum	type,
		const GLvoid *	data
	)

Update a section of a 3D image within the texture.

Parameters

level	The level of detail number, 0 is the base image, level n is the n-th mipmap
xoffset	x-offset of the region to update
yoffset	y-offset of the region to update
zoffset	z-offset of the region to update
the_width	Width of the region to update
the_height	Height of the region to update
the_depth	Depth of the region to update
format	Format of the data passed to this method
type	Type of the data passed to this method
data	Pointer to memory containing the data to upload

void get_image	(	GLint	level,
		GLint	format,
		GLenum	type,
		GLvoid *	img
	)

Get image data from this texture.

Parameters

level	The level of detail number, 0 is the base image, level n is the n-th mipmap
format	Format of the returned data
type	Type of the returned data
img	Pointer to memory to write the image data to

void generate_mipmap ( )

Generate mipmaps for this texture.

Public Member Functions

Static Public Member Functions

Detailed Description

template<GLenum Target = GL_TEXTURE_2D> class gls::texture< Target >

Constructor & Destructor Documentation

Member Function Documentation

template<GLenum Target = GL_TEXTURE_2D>
class gls::texture< Target >