OpenGLGraphicsContextCustomShader Struct Reference

Used to create custom shaders for use with an openGL 2D rendering context. More...

Public Member Functions

 OpenGLGraphicsContextCustomShader (const String &fragmentShaderCode)
 Creates a custom shader. More...
 
 ~OpenGLGraphicsContextCustomShader ()
 Destructor. More...
 
OpenGLShaderProgramgetProgram (LowLevelGraphicsContext &) const
 Returns the program, if it has been linked and is active. More...
 
void fillRect (LowLevelGraphicsContext &, const Rectangle< int > &area) const
 Applies the shader to a rectangle within the graphics context. More...
 
Result checkCompilation (LowLevelGraphicsContext &)
 Attempts to compile the program if necessary, and returns an error message if it fails. More...
 
const StringgetFragmentShaderCode () const noexcept
 Returns the code that was used to create this object. More...
 

Detailed Description

Used to create custom shaders for use with an openGL 2D rendering context.

Given a GL-based rendering context, you can write a fragment shader that applies some kind of per-pixel effect.

Constructor & Destructor Documentation

◆ OpenGLGraphicsContextCustomShader()

OpenGLGraphicsContextCustomShader::OpenGLGraphicsContextCustomShader ( const String fragmentShaderCode)

Creates a custom shader.

The shader code will not be compiled until actually needed, so it's OK to call this constructor when no GL context is active.

The code should be a normal fragment shader. As well as the usual GLSL variables, there is also an automatically declared varying vec2 called "pixelPos", which indicates the pixel position within the graphics context of the pixel being drawn. There is also a varying value "pixelAlpha", which indicates the alpha by which the pixel should be multiplied, so that the edges of any clip-region masks are anti-aliased correctly.

◆ ~OpenGLGraphicsContextCustomShader()

OpenGLGraphicsContextCustomShader::~OpenGLGraphicsContextCustomShader ( )

Destructor.

Member Function Documentation

◆ getProgram()

OpenGLShaderProgram* OpenGLGraphicsContextCustomShader::getProgram ( LowLevelGraphicsContext ) const

Returns the program, if it has been linked and is active.

This can be called when you're about to use fillRect, to set up any uniforms/textures that the program may require.

◆ fillRect()

void OpenGLGraphicsContextCustomShader::fillRect ( LowLevelGraphicsContext ,
const Rectangle< int > &  area 
) const

Applies the shader to a rectangle within the graphics context.

◆ checkCompilation()

Result OpenGLGraphicsContextCustomShader::checkCompilation ( LowLevelGraphicsContext )

Attempts to compile the program if necessary, and returns an error message if it fails.

◆ getFragmentShaderCode()

const String& OpenGLGraphicsContextCustomShader::getFragmentShaderCode ( ) const
noexcept

Returns the code that was used to create this object.


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