/*
** gl_postprocessstate.cpp
** Render state maintenance
**
**---------------------------------------------------------------------------
** Copyright 2016 Magnus Norddahl
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
**    notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
**    notice, this list of conditions and the following disclaimer in the
**    documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
**    derived from this software without specific prior written permission.
** 4. When not used as part of GZDoom or a GZDoom derivative, this code will be
**    covered by the terms of the GNU Lesser General Public License as published
**    by the Free Software Foundation; either version 2.1 of the License, or (at
**    your option) any later version.
** 5. Full disclosure of the entire project's source code, except for third
**    party libraries is mandatory. (NOTE: This clause is non-negotiable!)
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
*/

#include "templates.h"
#include "gl/system/gl_system.h"
#include "gl/system/gl_interface.h"
#include "gl/data/gl_data.h"
#include "gl/data/gl_vertexbuffer.h"
#include "gl/system/gl_cvars.h"
#include "gl/shaders/gl_shader.h"
#include "gl/renderer/gl_renderer.h"
#include "gl/renderer/gl_postprocessstate.h"

//-----------------------------------------------------------------------------
//
// Saves state modified by post processing shaders
//
//-----------------------------------------------------------------------------

FGLPostProcessState::FGLPostProcessState()
{
	glGetIntegerv(GL_ACTIVE_TEXTURE, &activeTex);
	glActiveTexture(GL_TEXTURE0);
	glGetIntegerv(GL_TEXTURE_BINDING_2D, &textureBinding);
	if (gl.flags & RFL_SAMPLER_OBJECTS)
	{
		glGetIntegerv(GL_SAMPLER_BINDING, &samplerBinding);
		glBindSampler(0, 0);
	}

	glGetBooleanv(GL_BLEND, &blendEnabled);
	glGetBooleanv(GL_SCISSOR_TEST, &scissorEnabled);
	glGetBooleanv(GL_DEPTH_TEST, &depthEnabled);
	glGetBooleanv(GL_MULTISAMPLE, &multisampleEnabled);
	glGetIntegerv(GL_CURRENT_PROGRAM, &currentProgram);
	glGetIntegerv(GL_BLEND_EQUATION_RGB, &blendEquationRgb);
	glGetIntegerv(GL_BLEND_EQUATION_ALPHA, &blendEquationAlpha);
	glGetIntegerv(GL_BLEND_SRC_RGB, &blendSrcRgb);
	glGetIntegerv(GL_BLEND_SRC_ALPHA, &blendSrcAlpha);
	glGetIntegerv(GL_BLEND_DST_RGB, &blendDestRgb);
	glGetIntegerv(GL_BLEND_DST_ALPHA, &blendDestAlpha);

	glDisable(GL_MULTISAMPLE);
	glDisable(GL_DEPTH_TEST);
	glDisable(GL_SCISSOR_TEST);
	glDisable(GL_BLEND);
}

//-----------------------------------------------------------------------------
//
// Restores state at the end of post processing
//
//-----------------------------------------------------------------------------

FGLPostProcessState::~FGLPostProcessState()
{
	if (blendEnabled)
		glEnable(GL_BLEND);
	else
		glDisable(GL_BLEND);

	if (scissorEnabled)
		glEnable(GL_SCISSOR_TEST);
	else
		glDisable(GL_SCISSOR_TEST);

	if (depthEnabled)
		glEnable(GL_DEPTH_TEST);
	else
		glDisable(GL_DEPTH_TEST);

	if (multisampleEnabled)
		glEnable(GL_MULTISAMPLE);
	else
		glDisable(GL_MULTISAMPLE);

	glBlendEquationSeparate(blendEquationRgb, blendEquationAlpha);
	glBlendFuncSeparate(blendSrcRgb, blendDestRgb, blendSrcAlpha, blendDestAlpha);

	glUseProgram(currentProgram);

	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_2D, textureBinding);
	if (gl.flags & RFL_SAMPLER_OBJECTS)
		glBindSampler(0, samplerBinding);
	glActiveTexture(activeTex);
}