Detailed Description

Guard to easily save and restore critical (modern) OpenGL state.

On instantiation StateGuard will store selected parts of the current OpenGL state. On destruction StateGuard will restore those settings, no matter of what has been happened in the meantime.

Usage example:

// open a scope block
{
    // store the current OpenGL state
    StateGuard guard;
 
    // perform a reduction on a custom FBO.
    m_fbo->bind();
    auto depthRange = m_reduction->reduce(inputDepthTex, m_fbo.get());
 
    // Since the reduction has changed the viewport, we want to restore the original one
    stateGuard.restoreState(StateGuard::Viewport);
 
    // do some more rendering
    // ...
}
// when the scope ends, guard will be destroyed and restore the previous OpenGL state
// (including the viewport, which has been restored before).

Public Types
enum	SaveFlags { None = 0 , Viewport = 1 << 0 , FBO = 1 << 1 , Program = 1 << 2 , Blending = 1 << 3 , DepthTest = 1 << 4 , ScissorTest = 1 << 5 , Smoothing = 1 << 6 , Stencil = 1 << 7 , Everything = Viewport \| FBO \| Program \| Blending \| DepthTest \| ScissorTest \| Smoothing \| Stencil }

Public Member Functions
	StateGuard (Flags< SaveFlags > saveFlags=Everything)
	Constructor, initializes the guard and saves the current state.

	StateGuard (StateGuard &&rhs)
	Move constructor needed to avoid double deletion when returning by value.

	~StateGuard ()
	Destructor, restores the state of all save flags given originally, if not done before.

void	restoreState (Flags< SaveFlags > saveFlagsToClear)
	Restores the state of the given save flags.

void	release (Flags< SaveFlags > saveFlagsToRelease)
	Marks the given save flags as restored without actually restoring them.

Member Enumeration Documentation

◆ SaveFlags

enum SaveFlags

Enumerator
Viewport	Save the viewport state (origin and extent)
FBO	Save the currently bound FBO.
Program	Save the currently bound shader/program.
Blending	Save the GL_BLEND enable and glBlendFunc states.
DepthTest	Save the GL_DEPTH_TEST, glDepthMask and glDepthFunc states.
ScissorTest	Save the GL_SCISSOR_TEST state.
Smoothing	Save the GL_LINE_SMOOTH and GL_POLYGON_SMOOTH states.
Stencil	Save GL_STENCIL_TEST+glStencilMask states; glStencilFunc+glStencilOp are not saved.
Everything	convenience value to include all save flags

Member Function Documentation

◆ restoreState()

void restoreState ( Flags< SaveFlags > saveFlagsToClear )

Restores the state of the given save flags.

Note: Calling this method is optional, the state will always be restored on destruction of the StateGuard object. Multiple subsequent calls to restoreState will always restore the original state during construction.

◆ release()

void release ( Flags< SaveFlags > saveFlagsToRelease )

Marks the given save flags as restored without actually restoring them.

In rare occasions you may want to delete a StateGuard without actually restoring the original state.

Note: This will completely dismiss the corresponding state, even an explicit restoreState() will no longer restore it after calling this function.

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

ImFusion/Core/GL/StateGuard.h