// 
//---------------------------------------------------------------------------
//
// Copyright(C) 2009-2016 Christoph Oelckers
// All rights reserved.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program.  If not, see http://www.gnu.org/licenses/
//
//--------------------------------------------------------------------------
//
/*
** gl_renderstate.cpp
** Render state maintenance
**
*/

#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_renderstate.h"
#include "gl/renderer/gl_colormap.h"
#include "gl/dynlights//gl_lightbuffer.h"
#include "gl/renderer/gl_renderbuffers.h"

void gl_SetTextureMode(int type);

FRenderState gl_RenderState;

CVAR(Bool, gl_direct_state_change, true, 0)


static VSMatrix identityMatrix(1);
TArray<VSMatrix> gl_MatrixStack;

//==========================================================================
//
//
//
//==========================================================================

void FRenderState::Reset()
{
	mTextureEnabled = true;
	mClipLineEnabled = mSplitEnabled = mBrightmapEnabled = mFogEnabled = mGlowEnabled = false;
	mColorMask[0] = mColorMask[1] = mColorMask[2] = mColorMask[3] = true;
	currentColorMask[0] = currentColorMask[1] = currentColorMask[2] = currentColorMask[3] = true;
	mFogColor.d = -1;
	mTextureMode = -1;
	mLightIndex = -1;
	mDesaturation = 0;
	mSrcBlend = GL_SRC_ALPHA;
	mDstBlend = GL_ONE_MINUS_SRC_ALPHA;
	mAlphaThreshold = 0.5f;
	mBlendEquation = GL_FUNC_ADD;
	mModelMatrixEnabled = false;
	mTextureMatrixEnabled = false;
	mObjectColor = 0xffffffff;
	mVertexBuffer = mCurrentVertexBuffer = NULL;
	mColormapState = CM_DEFAULT;
	mSoftLight = 0;
	mLightParms[0] = mLightParms[1] = mLightParms[2] = 0.0f;
	mLightParms[3] = -1.f;
	mSpecialEffect = EFF_NONE;
	mClipHeight = 0.f;
	mClipHeightDirection = 0.f;
	mShaderTimer = 0.0f;
	ClearClipSplit();

	stSrcBlend = stDstBlend = -1;
	stBlendEquation = -1;
	stAlphaThreshold = -1.f;
	stAlphaTest = 0;
	mLastDepthClamp = true;
	mInterpolationFactor = 0.0f;

	mColor.Set(1.0f, 1.0f, 1.0f, 1.0f);
	mCameraPos.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mGlowTop.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mGlowBottom.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mGlowTopPlane.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mGlowBottomPlane.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mSplitTopPlane.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mSplitBottomPlane.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mClipLine.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mDynColor.Set(0.0f, 0.0f, 0.0f, 0.0f);
	mEffectState = 0;
	activeShader = nullptr;
	mProjectionMatrix.loadIdentity();
	mViewMatrix.loadIdentity();
	mModelMatrix.loadIdentity();
	mTextureMatrix.loadIdentity();
	mPassType = NORMAL_PASS;
}

//==========================================================================
//
// Apply shader settings
//
//==========================================================================

bool FRenderState::ApplyShader()
{
	static const float nulvec[] = { 0.f, 0.f, 0.f, 0.f };
	if (mSpecialEffect > EFF_NONE)
	{
		activeShader = GLRenderer->mShaderManager->BindEffect(mSpecialEffect, mPassType);
	}
	else
	{
		activeShader = GLRenderer->mShaderManager->Get(mTextureEnabled ? mEffectState : 4, mAlphaThreshold >= 0.f, mPassType);
		activeShader->Bind();
	}

	int fogset = 0;

	if (mFogEnabled)
	{
		if ((mFogColor & 0xffffff) == 0)
		{
			fogset = gl_fogmode;
		}
		else
		{
			fogset = -gl_fogmode;
		}
	}

	glVertexAttrib4fv(VATTR_COLOR, mColor.vec);
	glVertexAttrib4fv(VATTR_NORMAL, mNormal.vec);

	activeShader->muDesaturation.Set(mDesaturation / 255.f);
	activeShader->muFogEnabled.Set(fogset);
	activeShader->muTextureMode.Set(mTextureMode);
	activeShader->muCameraPos.Set(mCameraPos.vec);
	activeShader->muLightParms.Set(mLightParms);
	activeShader->muFogColor.Set(mFogColor);
	activeShader->muObjectColor.Set(mObjectColor);
	activeShader->muDynLightColor.Set(mDynColor.vec);
	activeShader->muInterpolationFactor.Set(mInterpolationFactor);
	activeShader->muClipHeight.Set(mClipHeight);
	activeShader->muClipHeightDirection.Set(mClipHeightDirection);
	activeShader->muTimer.Set(gl_frameMS * mShaderTimer / 1000.f);
	activeShader->muAlphaThreshold.Set(mAlphaThreshold);
	activeShader->muLightIndex.Set(mLightIndex);	// will always be -1 for now
	activeShader->muClipSplit.Set(mClipSplit);

	if (mGlowEnabled)
	{
		activeShader->muGlowTopColor.Set(mGlowTop.vec);
		activeShader->muGlowBottomColor.Set(mGlowBottom.vec);
		activeShader->muGlowTopPlane.Set(mGlowTopPlane.vec);
		activeShader->muGlowBottomPlane.Set(mGlowBottomPlane.vec);
		activeShader->currentglowstate = 1;
	}
	else if (activeShader->currentglowstate)
	{
		// if glowing is on, disable it.
		activeShader->muGlowTopColor.Set(nulvec);
		activeShader->muGlowBottomColor.Set(nulvec);
		activeShader->muGlowTopPlane.Set(nulvec);
		activeShader->muGlowBottomPlane.Set(nulvec);
		activeShader->currentglowstate = 0;
	}

	if (mSplitEnabled)
	{
		activeShader->muSplitTopPlane.Set(mSplitTopPlane.vec);
		activeShader->muSplitBottomPlane.Set(mSplitBottomPlane.vec);
		activeShader->currentsplitstate = 1;
	}
	else if (activeShader->currentsplitstate)
	{
		activeShader->muSplitTopPlane.Set(nulvec);
		activeShader->muSplitBottomPlane.Set(nulvec);
		activeShader->currentsplitstate = 0;
	}

	if (mClipLineEnabled)
	{
		activeShader->muClipLine.Set(mClipLine.vec);
		activeShader->currentcliplinestate = 1;
	}
	else if (activeShader->currentcliplinestate)
	{
		activeShader->muClipLine.Set(-10000000.0, 0, 0, 0);
		activeShader->currentcliplinestate = 0;
	}

	if (mColormapState != activeShader->currentfixedcolormap)
	{
		float r, g, b;
		activeShader->currentfixedcolormap = mColormapState;
		if (mColormapState == CM_DEFAULT)
		{
			activeShader->muFixedColormap.Set(0);
		}
		else if (mColormapState > CM_DEFAULT && mColormapState < CM_MAXCOLORMAP)
		{
			if (FGLRenderBuffers::IsEnabled())
			{
				// When using postprocessing to apply the colormap, we must render the image fullbright here.
				activeShader->muFixedColormap.Set(2);
				activeShader->muColormapStart.Set(1, 1, 1, 1.f);
			}
			else
			{
				FSpecialColormap *scm = &SpecialColormaps[gl_fixedcolormap - CM_FIRSTSPECIALCOLORMAP];
				float m[] = { scm->ColorizeEnd[0] - scm->ColorizeStart[0],
					scm->ColorizeEnd[1] - scm->ColorizeStart[1], scm->ColorizeEnd[2] - scm->ColorizeStart[2], 0.f };

				activeShader->muFixedColormap.Set(1);
				activeShader->muColormapStart.Set(scm->ColorizeStart[0], scm->ColorizeStart[1], scm->ColorizeStart[2], 0.f);
				activeShader->muColormapRange.Set(m);
			}
		}
		else if (mColormapState == CM_FOGLAYER)
		{
			activeShader->muFixedColormap.Set(3);
		}
		else if (mColormapState == CM_LITE)
		{
			if (gl_enhanced_nightvision)
			{
				r = 0.375f, g = 1.0f, b = 0.375f;
			}
			else
			{
				r = g = b = 1.f;
			}
			activeShader->muFixedColormap.Set(2);
			activeShader->muColormapStart.Set(r, g, b, 1.f);
		}
		else if (mColormapState >= CM_TORCH)
		{
			int flicker = mColormapState - CM_TORCH;
			r = (0.8f + (7 - flicker) / 70.0f);
			if (r > 1.0f) r = 1.0f;
			b = g = r;
			if (gl_enhanced_nightvision) b = g * 0.75f;
			activeShader->muFixedColormap.Set(2);
			activeShader->muColormapStart.Set(r, g, b, 1.f);
		}
	}
	if (mTextureMatrixEnabled)
	{
		mTextureMatrix.matrixToGL(activeShader->texturematrix_index);
		activeShader->currentTextureMatrixState = true;
	}
	else if (activeShader->currentTextureMatrixState)
	{
		activeShader->currentTextureMatrixState = false;
		identityMatrix.matrixToGL(activeShader->texturematrix_index);
	}

	if (mModelMatrixEnabled)
	{
		mModelMatrix.matrixToGL(activeShader->modelmatrix_index);
		VSMatrix norm;
		norm.computeNormalMatrix(mModelMatrix);
		mNormalModelMatrix.matrixToGL(activeShader->normalmodelmatrix_index);
		activeShader->currentModelMatrixState = true;
	}
	else if (activeShader->currentModelMatrixState)
	{
		activeShader->currentModelMatrixState = false;
		identityMatrix.matrixToGL(activeShader->modelmatrix_index);
		identityMatrix.matrixToGL(activeShader->normalmodelmatrix_index);
	}
	return true;
}


//==========================================================================
//
// Apply State
//
//==========================================================================

void FRenderState::Apply()
{
	if (!gl_direct_state_change)
	{
		if (mSrcBlend != stSrcBlend || mDstBlend != stDstBlend)
		{
			stSrcBlend = mSrcBlend;
			stDstBlend = mDstBlend;
			glBlendFunc(mSrcBlend, mDstBlend);
		}
		if (mBlendEquation != stBlendEquation)
		{
			stBlendEquation = mBlendEquation;
			glBlendEquation(mBlendEquation);
		}
	}

	//ApplyColorMask(); I don't think this is needed.

	if (mVertexBuffer != mCurrentVertexBuffer)
	{
		if (mVertexBuffer == NULL) glBindBuffer(GL_ARRAY_BUFFER, 0);
		else mVertexBuffer->BindVBO();
		mCurrentVertexBuffer = mVertexBuffer;
	}
	if (!gl.legacyMode) 
	{
		ApplyShader();
	}
	else
	{
		ApplyFixedFunction();
	}
}



void FRenderState::ApplyColorMask()
{
	if ((mColorMask[0] != currentColorMask[0]) ||
		(mColorMask[1] != currentColorMask[1]) ||
		(mColorMask[2] != currentColorMask[2]) ||
		(mColorMask[3] != currentColorMask[3]))
	{
		glColorMask(mColorMask[0], mColorMask[1], mColorMask[2], mColorMask[3]);
		currentColorMask[0] = mColorMask[0];
		currentColorMask[1] = mColorMask[1];
		currentColorMask[2] = mColorMask[2];
		currentColorMask[3] = mColorMask[3];
	}
}

void FRenderState::ApplyMatrices()
{
	if (GLRenderer->mShaderManager != NULL)
	{
		GLRenderer->mShaderManager->ApplyMatrices(&mProjectionMatrix, &mViewMatrix, mPassType);
	}
}

void FRenderState::ApplyLightIndex(int index)
{
	if (!gl.legacyMode)
	{
		if (index > -1 && GLRenderer->mLights->GetBufferType() == GL_UNIFORM_BUFFER)
		{
			index = GLRenderer->mLights->BindUBO(index);
		}
		activeShader->muLightIndex.Set(index);
	}
}

void FRenderState::SetClipHeight(float height, float direction)
{
	mClipHeight = height;
	mClipHeightDirection = direction;
#if 1
	// This still doesn't work... :(
	if (gl.flags & RFL_NO_CLIP_PLANES) return;
#endif
	if (direction != 0.f)
	{
		/*
		if (gl.flags & RFL_NO_CLIP_PLANES)
		{
			glMatrixMode(GL_MODELVIEW);
			glPushMatrix();
			glLoadMatrixf(mViewMatrix.get());
			// Plane mirrors never are slopes.
			double d[4] = { 0, direction, 0, -direction * height };
			glClipPlane(GL_CLIP_PLANE0, d);
			glPopMatrix();
		}
		*/
		glEnable(GL_CLIP_DISTANCE0);
	}
	else
	{
		glDisable(GL_CLIP_DISTANCE0);	// GL_CLIP_PLANE0 is the same value so no need to make a distinction
	}
}
