GlsStateManager Class Reference

#include <gls_state_manager.h>

Public Member Functions
void	ResetOpenGLState (void)
void	Begin (const GLenum mode)
void	End (void)
void	BindTexture2D (const GLuint textureIndex)
void	LineWidth (const GLfloat lineWidth)
void	AlphaFunc (const GLenum func, const GLclampf ref)
void	Color (const GlsColor &color)
void	BlendFunc (const GLenum sfactor, const GLenum dfactor)
void	ShadeModel (const GLenum mode)
void	DepthFunc (const GLenum func)
void	EnableAlphaTest (const GlsBool enable)
void	EnableBlend (const GlsBool enable)
void	EnableCullFace (const GlsBool enable)
void	EnableDepthTest (const GlsBool enable)
void	EnableLineSmooth (const GlsBool enable)
void	EnableTexture2D (const GlsBool enable)
void	TexParameteri2D (const GLenum pname, const GLint param)
void	TexEnvi (const GLint param)

Static Public Member Functions
static GlsStateManager &	GetStateManager (void)

Static Public Attributes
static const GLuint	INVALID_GL_TEXTURE_INDEX = 0u

Protected Member Functions
	GlsStateManager (void)
virtual	~GlsStateManager ()

Protected Attributes
GLenum	_alphaFunc
GLclampf	_alphaRef
GlsBool	_alphaTest
GlsBool	_alphaBlend
GLenum	_alphaBlendSFactor
GLenum	_alphaBlendDFactor
GlsBool	_depthTest
GLenum	_depthFunc
GlsBool	_lineSmooth
GlsBool	_cullFace
GLenum	_shadeModel
GlsColor	_color
GlsBool	_texture2D
GLuint	_textureIndex2D
GLfloat	_lineWidth
GLenum	_polygonMode

Detailed Description

This class manages OpenGL context state and allows for minimizing calls to OpenGL.

Invariant

GlsGLAlphaFuncIsValid( _alphaFunc ), ( 0.0f <= _alphaRef ) && ( _alphaRef <= 1.0f ), GlsGLBlendFuncSFactorIsValid( _alphaBlendSFactor ), GlsGLBlendFuncDFactorIsValid( _alphaBlendDFactor ), GlsGLDepthFuncIsValid( _depthFunc ), GlsGLShadeModelIsValid( _shadeModel ), _color.IsValid(), ( ( GlsStateManager::LINE_WIDTH_MIN <= _lineWidth ) && ( _lineWidth <= GlsStateManager::LINE_WIDTH_MAX ) ), GlsGLPolygonModeIsValid( _polygonMode ) ), ( ( 0 == _glBeginCount ) || ( 1 == _glBeginCount ) ), ( 1 == _numInstCreated ), OpenGL state is synchronized with the state manager

Constructor & Destructor Documentation

GlsStateManager::GlsStateManager ( void  )

protected

Constructor - create an instance

Precondition

not within a begin/end pair, glGetError() == GL_NO_ERROR, no other state manager has been created

Postcondition

instance created, OpenGL state is synchronized with state manager

virtual GlsStateManager::~GlsStateManager ( )

protectedvirtual

Destructor - shall never be called

Precondition

none

Postcondition

none

Member Function Documentation

void GlsStateManager::AlphaFunc	(	const GLenum	func,
		const GLclampf	ref
	)

equivalent to glAlphaFunc() call

Parameters

func	GL alpha comparison mode
ref	GL alpha reference value

Precondition

GlsGLAlphaFuncIsValid( func ), 0.0f <= ref <= 1.0f, not within a begin/end pair

Postcondition

new GL alpha mode and reference are set

void GlsStateManager::Begin

(

const GLenum

mode

)

equivalent to glBegin() call

Parameters

mode	primitive mode to begin

Precondition

must not be within a begin/end pair, mode is a valid GL primitive mode

Postcondition

a new primitive is started

void GlsStateManager::BindTexture2D

(

const GLuint

textureIndex

)

equivalent to glBindTexture( GL_TEXTURE_2D, .. ) call

Parameters

textureIndex

GL texture index of texture to bind ( >0 )

Precondition

textureIndex > 0, textureIndex is a valid GL texture index, not within a begin/end pair

Postcondition

desired 2D texture is bound to GL

void GlsStateManager::BlendFunc	(	const GLenum	sfactor,
		const GLenum	dfactor
	)

equivalent to glBlendFunc() call

Parameters

sfactor	alpha source mode
dfactor	alpha destination mode

Precondition

GlsGLBlendFuncSFactorIsValid( sfactor ), GlsGLBlendFuncDFactorIsValid( dfactor ), not within a begin/end pair

Postcondition

new GL alpha blend mode is set

void GlsStateManager::Color

(

const GlsColor &

color

)

equivalent to glColor() call

Parameters

color

new color

Precondition

color.IsValid()

Postcondition

new GL color is set

void GlsStateManager::DepthFunc

(

const GLenum

func

)

equivalent to glDepthFunc() call

Parameters

func	new GL depth function

Precondition

GlsGLDepthFuncIsValid( func ), not within a begin/end pair

Postcondition

new GL depth function is set

void GlsStateManager::EnableAlphaTest

(

const GlsBool

enable

)

equivalent to glEnable(GL_ALPHA_TEST)/glDisable(GL_ALPHA_TEST) call

Parameters

enable

GLS_TRUE to enable else GLS_FALSE

Precondition

not within a begin/end pair

Postcondition

GL_ALPHA_TEST is enabled if enable == GLS_TRUE else, GL_ALPHA_TEST is disabled

void GlsStateManager::EnableBlend

(

const GlsBool

enable

)

equivalent to glEnable(GL_BLEND)/glDisable(GL_BLEND) call

Parameters

enable

GLS_TRUE to enable else GLS_FALSE

Precondition

not within a begin/end pair

Postcondition

GL_BLEND is enabled if enable == GLS_TRUE else, GL_BLEND is disabled

void GlsStateManager::EnableCullFace

(

const GlsBool

enable

)

equivalent to glEnable(GL_CULL_FACE)/glDisable(GL_CULL_FACE) call

Parameters

enable

GLS_TRUE to enable else GLS_FALSE

Precondition

not within a begin/end pair

Postcondition

GL_CULL_FACE is enabled if enable == GLS_TRUE else, GL_CULL_FACE is disabled

void GlsStateManager::EnableDepthTest

(

const GlsBool

enable

)

equivalent to glEnable(GL_DEPTH_TEST)/glDisable(GL_DEPTH_TEST) call

Parameters

enable

GLS_TRUE to enable else GLS_FALSE

Precondition

not within a begin/end pair

Postcondition

GL_DEPTH_TEST is enabled if enable == GLS_TRUE else, GL_DEPTH_TEST is disabled

void GlsStateManager::EnableLineSmooth

(

const GlsBool

enable

)

equivalent to glEnable(GL_LINE_SMOOTH)/glDisable(GL_LINE_SMOOTH) call

Parameters

enable

GLS_TRUE to enable else GLS_FALSE

Precondition

not within a begin/end pair

Postcondition

GL_LINE_SMOOTH is enabled if enable == GLS_TRUE else, GL_LINE_SMOOTH is disabled

void GlsStateManager::EnableTexture2D

(

const GlsBool

enable

)

equivalent to glEnable(GL_TEXTURE_2D)/glDisable(GL_TEXTURE_2D) call

Parameters

enable

GLS_TRUE to enable else GLS_FALSE

Precondition

not within a begin/end pair

Postcondition

GL_TEXTURE_2D is enabled if enable == GLS_TRUE else, GL_TEXTURE_2D is disabled

void GlsStateManager::End

(

void

)

equivalent to glEnd() call

Precondition

must be called within a begin/end pair

Postcondition

primitive is ended

static GlsStateManager& GlsStateManager::GetStateManager ( void  )

static

Get the singleton GlsStateManager instance

Precondition

precondition for constructor must hold first time this method is called

Postcondition

postcondition for constructor holds after the first time this method is called

Returns

the singleton GlsStateManager instance

void GlsStateManager::LineWidth

(

const GLfloat

lineWidth

)

equivalent to glLineWidth() call

Parameters

lineWidth

new line width ( GlsStateManager::LINE_WIDTH_MIN <= width <= GlsStateManager::LINE_WIDTH_MAX )

Precondition

GlsStateManager::LINE_WIDTH_MIN <= width <= GlsStateManager::LINE_WIDTH_MAX, not within a begin/end pair

Postcondition

GL has new line width

void GlsStateManager::ResetOpenGLState

(

void

)

Reset the cached GL state variables and set them into the GL state

Precondition

none

Postcondition

cached GL state variables are set to default values and GL is synchronized with state manager

void GlsStateManager::ShadeModel

(

const GLenum

mode

)

equivalent to glShadeModel() call

Parameters

mode	new GL shade mode

Precondition

GlsGLShadeModelIsValid( mode ), not within a begin/end pair

Postcondition

new GL shade model is set

void GlsStateManager::TexEnvi

(

const GLint

param

)

equivalent to glTexEnvi(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,...) call

Parameters

param

new value for texture environment mode

Precondition

GlsGLTetxureEnvModeIsValid( param ), not within a begin/end pair

Postcondition

GL texture environment mode is set to new value

void GlsStateManager::TexParameteri2D	(	const GLenum	pname,
		const GLint	param
	)

equivalent to glTexParameteri(GL_TEXTURE_2D,...) call

Parameters

pname	GL texture parameter name
param	new value for indicated parameter

Precondition

GlsGLTextureParameterIsValid( pname ), pname == GL_TEXTURE_MIN_FILTER -> GlsGLTextureMinFilterIsValid( param ), pname == GL_TEXTURE_MAG_FITLER -> GlsGLTextureMagFilterIsValid( param ), pname == GL_TEXTURE_WRAP_S -> GlsGLTextureWrapIsValid( param ), pname == GL_TEXTURE_WRAP_T -> GlsGLTextureWrapIsValid( param ), not within a begin/end pair

Postcondition

given GL texture parameter is set to new value

Member Data Documentation

GlsBool GlsStateManager::_alphaBlend

protected

current GL Alpha Blending state

GLenum GlsStateManager::_alphaBlendDFactor

protected

current GL Alpha Blending destination factor

GLenum GlsStateManager::_alphaBlendSFactor

protected

current GL Alpha Blending source factor

GLenum GlsStateManager::_alphaFunc

protected

current GL alpha function

GLclampf GlsStateManager::_alphaRef

protected

current GL alpha reference value

GlsBool GlsStateManager::_alphaTest

protected

current GL Alpha Testing state (Screen door transparency)

GlsColor GlsStateManager::_color

protected

current GL Drawing color

GlsBool GlsStateManager::_cullFace

protected

current GL Backface culling state

GLenum GlsStateManager::_depthFunc

protected

current GL Depth Testing function

GlsBool GlsStateManager::_depthTest

protected

current GL Depth Testing state

GlsBool GlsStateManager::_lineSmooth

protected

current GL Line anti-aliasing

GLfloat GlsStateManager::_lineWidth

protected

current GL Line width

GLenum GlsStateManager::_polygonMode

protected

current GL Polygon Draw Mode

GLenum GlsStateManager::_shadeModel

protected

current GL shading model

GlsBool GlsStateManager::_texture2D

protected

current GL 2D texture state

GLuint GlsStateManager::_textureIndex2D

protected

current index of GL 2D bound texture else GlsStateManager::INVALID_GL_TEXTURE_INDEX if no texture is bound

const GLuint GlsStateManager::INVALID_GL_TEXTURE_INDEX = 0u

static

invalid GL texture index