Shader class (vertex and fragment) More...

#include <Shader.hpp>

Inheritance diagram for cpp3ds::Shader:

Classes
struct	CurrentTextureType
	Special type that can be passed to setParameter, and that represents the texture of the object being drawn. More...

Public Types
enum	Type { Vertex, Geometry }
	Types of shaders. More...

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

	~Shader ()
	Destructor. More...

bool	loadFromFile (const std::string &filename, Type type)
	Load either the vertex or fragment shader from a file. More...

bool	loadFromFile (const std::string &vertexShaderFilename, const std::string &fragmentShaderFilename)
	Load both the vertex and fragment shaders from files. More...

bool	loadFromMemory (const std::string &shader, Type type)
	Load either the vertex or fragment shader from a source code in memory. More...

bool	loadFromMemory (const std::string &vertexShader, const std::string &fragmentShader)
	Load both the vertex and fragment shaders from source codes in memory. More...

bool	loadBinary (const Uint8 *data, const Uint32 size, Type type)

bool	loadFromStream (InputStream &stream, Type type)
	Load either the vertex or fragment shader from a custom stream. More...

bool	loadFromStream (InputStream &vertexShaderStream, InputStream &fragmentShaderStream)
	Load both the vertex and fragment shaders from custom streams. More...

void	setParameter (const std::string &name, float x)
	Change a float parameter of the shader. More...

void	setParameter (const std::string &name, float x, float y)
	Change a 2-components vector parameter of the shader. More...

void	setParameter (const std::string &name, float x, float y, float z)
	Change a 3-components vector parameter of the shader. More...

void	setParameter (const std::string &name, float x, float y, float z, float w)
	Change a 4-components vector parameter of the shader. More...

void	setParameter (const std::string &name, const Vector2f &vector)
	Change a 2-components vector parameter of the shader. More...

void	setParameter (const std::string &name, const Vector3f &vector)
	Change a 3-components vector parameter of the shader. More...

void	setParameter (const std::string &name, const Color &color)
	Change a color parameter of the shader. More...

void	setParameter (const std::string &name, const cpp3ds::Transform &transform)
	Change a matrix parameter of the shader. More...

void	setParameter (const std::string &name, const Texture &texture)
	Change a texture parameter of the shader. More...

void	setParameter (const std::string &name, CurrentTextureType)
	Change a texture parameter of the shader. More...

unsigned int	getNativeHandle () const
	Get the underlying OpenGL handle of the shader. More...

Static Public Member Functions
static void	bind (const Shader *shader)
	Bind a shader for rendering. More...

static bool	isAvailable ()
	Tell whether or not the system supports shaders. More...

Static Public Attributes
static Shader	Default

static CurrentTextureType	CurrentTexture
	Represents the texture of the object being drawn. More...

Detailed Description

Shader class (vertex and fragment)

Shaders are programs written using a specific language, executed directly by the graphics card and allowing to apply real-time operations to the rendered entities.

There are two kinds of shaders:

Vertex shaders, that process vertices
Fragment (pixel) shaders, that process pixels

A cpp3ds::Shader can be composed of either a vertex shader alone, a fragment shader alone, or both combined (see the variants of the load functions).

Shaders are written in GLSL, which is a C-like language dedicated to OpenGL shaders. You'll probably need to learn its basics before writing your own shaders for cpp3ds.

Like any C/C++ program, a shader has its own variables that you can set from your C++ application. cpp3ds::Shader handles 5 different types of variables:

floats
vectors (2, 3 or 4 components)
colors
textures
transforms (matrices)

The value of the variables can be changed at any time with the various overloads of the setParameter function:

shader.setParameter("offset", 2.f);
shader.setParameter("point", 0.5f, 0.8f, 0.3f);
shader.setParameter("color", cpp3ds::Color(128, 50, 255));
shader.setParameter("matrix", transform); // transform is a cpp3ds::Transform
shader.setParameter("overlay", texture); // texture is a cpp3ds::Texture
shader.setParameter("texture", cpp3ds::Shader::CurrentTexture);

The special Shader::CurrentTexture argument maps the given texture variable to the current texture of the object being drawn (which cannot be known in advance).

To apply a shader to a drawable, you must pass it as an additional parameter to the Draw function:

window.draw(sprite, &shader);

... which is in fact just a shortcut for this:

cpp3ds::RenderStates states;
states.shader = &shader;
window.draw(sprite, states);

In the code above we pass a pointer to the shader, because it may be null (which means "no shader").

Shaders can be used on any drawable, but some combinations are not interesting. For example, using a vertex shader on a cpp3ds::Sprite is limited because there are only 4 vertices, the sprite would have to be subdivided in order to apply wave effects. Another bad example is a fragment shader with cpp3ds::Text: the texture of the text is not the actual text that you see on screen, it is a big texture containing all the characters of the font in an arbitrary order; thus, texture lookups on pixels other than the current one may not give you the expected result.

Shaders can also be used to apply global post-effects to the current contents of the target. This can be done in two different ways:

draw everything to a cpp3ds::RenderTexture, then draw it to the main target using the shader
draw everything directly to the main target, then use cpp3ds::Texture::update(Window&) to copy its contents to a texture and draw it to the main target using the shader

The first technique is more optimized because it doesn't involve retrieving the target's pixels to system memory, but the second one doesn't impact the rendering process and can be easily inserted anywhere without impacting all the code.

Like cpp3ds::Texture that can be used as a raw OpenGL texture, cpp3ds::Shader can also be used directly as a raw shader for custom OpenGL geometry.

cpp3ds::Shader::bind(&shader);
... render OpenGL geometry ...
cpp3ds::Shader::bind(NULL);

Definition at line 53 of file Shader.hpp.

Member Enumeration Documentation

enum cpp3ds::Shader::Type

Types of shaders.

Enumerator
Vertex	Vertex shader.
Geometry	Geometry shader.

Definition at line 63 of file Shader.hpp.

Constructor & Destructor Documentation

cpp3ds::Shader::Shader ( )

Default constructor.

This constructor creates an invalid shader.

cpp3ds::Shader::~Shader ( )

Destructor.

Member Function Documentation

static void cpp3ds::Shader::bind ( const Shader * shader )

static

Bind a shader for rendering.

This function is not part of the graphics API, it mustn't be used when drawing cpp3ds entities. It must be used only if you mix cpp3ds::Shader with OpenGL code.

cpp3ds::Shader s1, s2;
...
cpp3ds::Shader::bind(&s1);
// draw OpenGL stuff that use s1...
cpp3ds::Shader::bind(&s2);
// draw OpenGL stuff that use s2...
cpp3ds::Shader::bind(NULL);
// draw OpenGL stuff that use no shader...

Parameters

shader Shader to bind, can be null to use no shader

unsigned int cpp3ds::Shader::getNativeHandle ( ) const

Get the underlying OpenGL handle of the shader.

You shouldn't need to use this function, unless you have very specific stuff to implement that cpp3ds doesn't support, or implement a temporary workaround until a bug is fixed.

Returns: OpenGL handle of the shader or 0 if not yet loaded

static bool cpp3ds::Shader::isAvailable ( )

static

Tell whether or not the system supports shaders.

This function should always be called before using the shader features. If it returns false, then any attempt to use cpp3ds::Shader will fail.

Returns: True if shaders are supported, false otherwise

bool cpp3ds::Shader::loadFromFile	(	const std::string &	filename,
		Type	type
	)

Load either the vertex or fragment shader from a file.

This function loads a single shader, either vertex or fragment, identified by the second argument. The source must be a text file containing a valid shader in GLSL language. GLSL is a C-like language dedicated to OpenGL shaders; you'll probably need to read a good documentation for it before writing your own shaders.

Parameters

filename	Path of the vertex or fragment shader file to load
type	Type of shader (vertex or fragment)

Returns: True if loading succeeded, false if it failed

See also: loadFromMemory, loadFromStream

bool cpp3ds::Shader::loadFromFile	(	const std::string &	vertexShaderFilename,
		const std::string &	fragmentShaderFilename
	)

Load both the vertex and fragment shaders from files.

This function loads both the vertex and the fragment shaders. If one of them fails to load, the shader is left empty (the valid shader is unloaded). The sources must be text files containing valid shaders in GLSL language. GLSL is a C-like language dedicated to OpenGL shaders; you'll probably need to read a good documentation for it before writing your own shaders.

Parameters

vertexShaderFilename	Path of the vertex shader file to load
fragmentShaderFilename	Path of the fragment shader file to load

Returns: True if loading succeeded, false if it failed

See also: loadFromMemory, loadFromStream

bool cpp3ds::Shader::loadFromMemory	(	const std::string &	shader,
		Type	type
	)

Load either the vertex or fragment shader from a source code in memory.

This function loads a single shader, either vertex or fragment, identified by the second argument. The source code must be a valid shader in GLSL language. GLSL is a C-like language dedicated to OpenGL shaders; you'll probably need to read a good documentation for it before writing your own shaders.

Parameters

shader	String containing the source code of the shader
type	Type of shader (vertex or fragment)

Returns: True if loading succeeded, false if it failed

See also: loadFromFile, loadFromStream

bool cpp3ds::Shader::loadFromMemory	(	const std::string &	vertexShader,
		const std::string &	fragmentShader
	)

Load both the vertex and fragment shaders from source codes in memory.

This function loads both the vertex and the fragment shaders. If one of them fails to load, the shader is left empty (the valid shader is unloaded). The sources must be valid shaders in GLSL language. GLSL is a C-like language dedicated to OpenGL shaders; you'll probably need to read a good documentation for it before writing your own shaders.

Parameters

vertexShader	String containing the source code of the vertex shader
fragmentShader	String containing the source code of the fragment shader

Returns: True if loading succeeded, false if it failed

See also: loadFromFile, loadFromStream

bool cpp3ds::Shader::loadFromStream	(	InputStream &	stream,
		Type	type
	)

Load either the vertex or fragment shader from a custom stream.

This function loads a single shader, either vertex or fragment, identified by the second argument. The source code must be a valid shader in GLSL language. GLSL is a C-like language dedicated to OpenGL shaders; you'll probably need to read a good documentation for it before writing your own shaders.

Parameters

stream	Source stream to read from
type	Type of shader (vertex or fragment)

Returns: True if loading succeeded, false if it failed

See also: loadFromFile, loadFromMemory

bool cpp3ds::Shader::loadFromStream	(	InputStream &	vertexShaderStream,
		InputStream &	fragmentShaderStream
	)

Load both the vertex and fragment shaders from custom streams.

This function loads both the vertex and the fragment shaders. If one of them fails to load, the shader is left empty (the valid shader is unloaded). The source codes must be valid shaders in GLSL language. GLSL is a C-like language dedicated to OpenGL shaders; you'll probably need to read a good documentation for it before writing your own shaders.

Parameters

vertexShaderStream	Source stream to read the vertex shader from
fragmentShaderStream	Source stream to read the fragment shader from

Returns: True if loading succeeded, false if it failed

See also: loadFromFile, loadFromMemory

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		float	x
	)

Change a float parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a float (float GLSL type).

Example:

uniform float myparam; // this is the variable in the shader

shader.setParameter("myparam", 5.2f);

Parameters

name	Name of the parameter in the shader
x	Value to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		float	x,
		float	y
	)

Change a 2-components vector parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a 2x1 vector (vec2 GLSL type).

Example:

uniform vec2 myparam; // this is the variable in the shader

shader.setParameter("myparam", 5.2f, 6.0f);

Parameters

name	Name of the parameter in the shader
x	First component of the value to assign
y	Second component of the value to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		float	x,
		float	y,
		float	z
	)

Change a 3-components vector parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a 3x1 vector (vec3 GLSL type).

Example:

uniform vec3 myparam; // this is the variable in the shader

shader.setParameter("myparam", 5.2f, 6.0f, -8.1f);

Parameters

name	Name of the parameter in the shader
x	First component of the value to assign
y	Second component of the value to assign
z	Third component of the value to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		float	x,
		float	y,
		float	z,
		float	w
	)

Change a 4-components vector parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a 4x1 vector (vec4 GLSL type).

Example:

uniform vec4 myparam; // this is the variable in the shader

shader.setParameter("myparam", 5.2f, 6.0f, -8.1f, 0.4f);

Parameters

name	Name of the parameter in the shader
x	First component of the value to assign
y	Second component of the value to assign
z	Third component of the value to assign
w	Fourth component of the value to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		const Vector2f &	vector
	)

Change a 2-components vector parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a 2x1 vector (vec2 GLSL type).

Example:

uniform vec2 myparam; // this is the variable in the shader

shader.setParameter("myparam", cpp3ds::Vector2f(5.2f, 6.0f));

Parameters

name	Name of the parameter in the shader
vector	Vector to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		const Vector3f &	vector
	)

Change a 3-components vector parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a 3x1 vector (vec3 GLSL type).

Example:

uniform vec3 myparam; // this is the variable in the shader

shader.setParameter("myparam", cpp3ds::Vector3f(5.2f, 6.0f, -8.1f));

Parameters

name	Name of the parameter in the shader
vector	Vector to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		const Color &	color
	)

Change a color parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a 4x1 vector (vec4 GLSL type).

It is important to note that the components of the color are normalized before being passed to the shader. Therefore, they are converted from range [0 .. 255] to range [0 .. 1]. For example, a cpp3ds::Color(255, 125, 0, 255) will be transformed to a vec4(1.0, 0.5, 0.0, 1.0) in the shader.

Example:

uniform vec4 color; // this is the variable in the shader

shader.setParameter("color", cpp3ds::Color(255, 128, 0, 255));

Parameters

name	Name of the parameter in the shader
color	Color to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		const cpp3ds::Transform &	transform
	)

Change a matrix parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a 4x4 matrix (mat4 GLSL type).

Example:

uniform mat4 matrix; // this is the variable in the shader

cpp3ds::Transform transform;
transform.translate(5, 10);
shader.setParameter("matrix", transform);

Parameters

name	Name of the parameter in the shader
transform	Transform to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		const Texture &	texture
	)

Change a texture parameter of the shader.

name is the name of the variable to change in the shader. The corresponding parameter in the shader must be a 2D texture (sampler2D GLSL type).

Example:

uniform sampler2D the_texture; // this is the variable in the shader

cpp3ds::Texture texture;
...
shader.setParameter("the_texture", texture);

It is important to note that texture must remain alive as long as the shader uses it, no copy is made internally.

To use the texture of the object being draw, which cannot be known in advance, you can pass the special value cpp3ds::Shader::CurrentTexture:

shader.setParameter("the_texture", cpp3ds::Shader::CurrentTexture).

Parameters

name	Name of the texture in the shader
texture	Texture to assign

void cpp3ds::Shader::setParameter	(	const std::string &	name,
		CurrentTextureType
	)

Change a texture parameter of the shader.

This overload maps a shader texture variable to the texture of the object being drawn, which cannot be known in advance. The second argument must be cpp3ds::Shader::CurrentTexture. The corresponding parameter in the shader must be a 2D texture (sampler2D GLSL type).

Example:

uniform sampler2D current; // this is the variable in the shader

shader.setParameter("current", cpp3ds::Shader::CurrentTexture);

Parameters

name	Name of the texture in the shader

Member Data Documentation

CurrentTextureType cpp3ds::Shader::CurrentTexture

static

Represents the texture of the object being drawn.

See also: setParameter(const std::string&, CurrentTextureType)

Definition at line 84 of file Shader.hpp.

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

Shader.hpp

Classes

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation