/** 
 * @file llsky.cpp
 * @brief IndraWorld sky class 
 *
 * $LicenseInfo:firstyear=2000&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 * 
 * This library 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;
 * version 2.1 of the License only.
 * 
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * 
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

//	Ideas:
//		-haze should be controlled by global query from sims
//		-need secondary optical effects on sun (flare)
//		-stars should be brought down from sims
//		-star intensity should be driven by global ambient level from sims,
//		 so that eclipses, etc can be easily done.
//

#include "llviewerprecompiledheaders.h"

#include "llsky.h"

// linden library includes
#include "llerror.h"
#include "llmath.h"
#include "math.h"
#include "v4color.h"

#include "llviewerobjectlist.h"
#include "llviewerobject.h"
#include "llviewercamera.h"
#include "pipeline.h"
#include "lldrawpool.h"

#include "llvosky.h"
#include "llcubemap.h"
#include "llviewercontrol.h"

#include "llvowlsky.h"

F32 azimuth_from_vector(const LLVector3 &v);
F32 elevation_from_vector(const LLVector3 &v);

LLSky				gSky;
// ---------------- LLSky ----------------

const F32 LLSky::NIGHTTIME_ELEVATION = -8.0f; // degrees
const F32 LLSky::NIGHTTIME_ELEVATION_COS = (F32)sin(NIGHTTIME_ELEVATION*DEG_TO_RAD);

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

LLSky::LLSky()
{
	// Set initial clear color to black
	// Set fog color 
	mFogColor.mV[VRED] = mFogColor.mV[VGREEN] = mFogColor.mV[VBLUE] = 0.5f;
	mFogColor.mV[VALPHA] = 0.0f;

	mLightingGeneration = 0;
	mUpdatedThisFrame = TRUE;
	mSunPhase = 0.f;
}


LLSky::~LLSky()
{
}

void LLSky::cleanup()
{
	mVOSkyp = NULL;
	mVOWLSkyp = NULL;
	mVOGroundp = NULL;
}

void LLSky::destroyGL()
{
	if (!mVOSkyp.isNull() && mVOSkyp->getCubeMap())
	{
		mVOSkyp->cleanupGL();
	}
	if (mVOWLSkyp.notNull())
	{
		mVOWLSkyp->cleanupGL();
	}
}

void LLSky::restoreGL()
{
	if (mVOSkyp)
	{
		mVOSkyp->restoreGL();
	}
	if (mVOWLSkyp)
	{
		mVOWLSkyp->restoreGL();
	}
}

void LLSky::resetVertexBuffers()
{
	if (gSky.mVOSkyp.notNull())
	{
		gPipeline.resetVertexBuffers(gSky.mVOSkyp->mDrawable);
		gPipeline.resetVertexBuffers(gSky.mVOGroundp->mDrawable);
		gPipeline.markRebuild(gSky.mVOSkyp->mDrawable, LLDrawable::REBUILD_ALL, TRUE);
		gPipeline.markRebuild(gSky.mVOGroundp->mDrawable, LLDrawable::REBUILD_ALL, TRUE);
	}
	if (gSky.mVOWLSkyp.notNull())
	{
		gSky.mVOWLSkyp->resetVertexBuffers();
		gPipeline.resetVertexBuffers(gSky.mVOWLSkyp->mDrawable);
		gPipeline.markRebuild(gSky.mVOWLSkyp->mDrawable, LLDrawable::REBUILD_ALL, TRUE);
	}
}

void LLSky::setSunDirection(const LLVector3 &sun_direction, const LLVector3 &moon_direction)
{
	if(mVOSkyp.notNull()) {
        mVOSkyp->setSunDirection(sun_direction, moon_direction);
	}
}

LLVector3 LLSky::getSunDirection() const
{
	if (mVOSkyp)
	{
		return mVOSkyp->getToSun();
	}
	else
	{
		return LLVector3::z_axis;
	}
}


LLVector3 LLSky::getMoonDirection() const
{
	if (mVOSkyp)
	{
		return mVOSkyp->getToMoon();
	}
	else
	{
		return LLVector3::z_axis;
	}
}


LLColor4 LLSky::getSunDiffuseColor() const
{
	if (mVOSkyp)
	{
		return LLColor4(mVOSkyp->getSunDiffuseColor());
	}
	else
	{
		return LLColor4(1.f, 1.f, 1.f, 1.f);
	}
}

LLColor4 LLSky::getSunAmbientColor() const
{
	if (mVOSkyp)
	{
		return LLColor4(mVOSkyp->getSunAmbientColor());
	}
	else
	{
		return LLColor4(0.f, 0.f, 0.f, 1.f);
	}
}


LLColor4 LLSky::getMoonDiffuseColor() const
{
	if (mVOSkyp)
	{
		return LLColor4(mVOSkyp->getMoonDiffuseColor());
	}
	else
	{
		return LLColor4(1.f, 1.f, 1.f, 1.f);
	}
}

LLColor4 LLSky::getMoonAmbientColor() const
{
	if (mVOSkyp)
	{
		return LLColor4(mVOSkyp->getMoonAmbientColor());
	}
	else
	{
		return LLColor4(0.f, 0.f, 0.f, 0.f);
	}
}


LLColor4 LLSky::getTotalAmbientColor() const
{
	if (mVOSkyp)
	{
		return mVOSkyp->getTotalAmbientColor();
	}
	else
	{
		return LLColor4(1.f, 1.f, 1.f, 1.f);
	}
}


BOOL LLSky::sunUp() const
{
	if (mVOSkyp)
	{
		return mVOSkyp->isSunUp();
	}
	else
	{
		return TRUE;
	}
}


LLColor4U LLSky::getFadeColor() const
{
	if (mVOSkyp)
	{
		return mVOSkyp->getFadeColor();
	}
	else
	{
		return LLColor4(1.f, 1.f, 1.f, 1.f);
	}
}


//////////////////////////////////////////////////////////////////////
// Public Methods
//////////////////////////////////////////////////////////////////////

void LLSky::init(const LLVector3 &sun_direction)
{
	LLGLState::checkStates();
	LLGLState::checkTextureChannels();

	mVOWLSkyp = static_cast<LLVOWLSky*>(gObjectList.createObjectViewer(LLViewerObject::LL_VO_WL_SKY, NULL));
	mVOWLSkyp->initSunDirection(sun_direction, LLVector3::zero);
	gPipeline.createObject(mVOWLSkyp.get());

	LLGLState::checkStates();
	LLGLState::checkTextureChannels();

	mVOSkyp = (LLVOSky *)gObjectList.createObjectViewer(LLViewerObject::LL_VO_SKY, NULL);

	LLGLState::checkStates();
	LLGLState::checkTextureChannels();

	mVOSkyp->initSunDirection(sun_direction, LLVector3());

	LLGLState::checkStates();
	LLGLState::checkTextureChannels();

	gPipeline.createObject((LLViewerObject *)mVOSkyp);

	LLGLState::checkStates();
	LLGLState::checkTextureChannels();

	mVOGroundp = (LLVOGround*)gObjectList.createObjectViewer(LLViewerObject::LL_VO_GROUND, NULL);
	LLVOGround *groundp = mVOGroundp;
	gPipeline.createObject((LLViewerObject *)groundp);

	LLGLState::checkStates();
	LLGLState::checkTextureChannels();

	gSky.setFogRatio(gSavedSettings.getF32("RenderFogRatio"));	

	////////////////////////////
	//
	// Legacy code, ignore
	//
	//

	// Get the parameters.
	mSunDefaultPosition = gSavedSettings.getVector3("SkySunDefaultPosition");

	LLGLState::checkStates();
	LLGLState::checkTextureChannels();

	if (gSavedSettings.getBOOL("SkyOverrideSimSunPosition"))
	{
		setSunDirection(mSunDefaultPosition, -mSunDefaultPosition);
	}
	else
	{
		setSunDirection(sun_direction, -sun_direction);
	}

	LLGLState::checkStates();
	LLGLState::checkTextureChannels();

	mUpdatedThisFrame = TRUE;
}


void LLSky::setCloudDensityAtAgent(F32 cloud_density)
{
	if (mVOSkyp)
	{
		mVOSkyp->setCloudDensity(cloud_density);
	}
}


void LLSky::setWind(const LLVector3& average_wind)
{
	if (mVOSkyp)
	{
		mVOSkyp->setWind(average_wind);
	}
}


void LLSky::propagateHeavenlyBodies(F32 dt)
{
// 	if (!mOverrideSimSunPosition)
// 	{
// 		LLVector3 curr_dir = getSunDirection();
// 		LLVector3 diff = mSunTargDir - curr_dir;
// 		const F32 dist = diff.normVec();
// 		if (dist > 0)
// 		{
// 			const F32 step = llmin (dist, 0.00005f);
// 			//const F32 step = min (dist, 0.0001);
// 			diff *= step;
// 			curr_dir += diff;
// 			curr_dir.normVec();
// 			if (mVOSkyp)
// 			{
// 				mVOSkyp->setSunDirection(curr_dir);
// 			}
// 		}
// 	}
}

F32 LLSky::getSunPhase() const
{
	return mSunPhase;
}

void LLSky::setSunPhase(const F32 phase)
{
	mSunPhase = phase;
}

//////////////////////////////////////////////////////////////////////
// Private Methods
//////////////////////////////////////////////////////////////////////


LLColor4 LLSky::getSkyFogColor() const
{
	if (mVOSkyp)
	{
		return mVOSkyp->getSkyFogColor();
	}

	return LLColor4(1.f, 1.f, 1.f, 1.f);
}

void LLSky::updateFog(const F32 distance)
{
	if (mVOSkyp)
	{
		mVOSkyp->updateFog(distance);
	}
}

void LLSky::updateCull()
{
	// *TODO: do culling for wl sky properly -Brad
}

void LLSky::updateSky()
{
	if (!gPipeline.hasRenderType(LLPipeline::RENDER_TYPE_SKY))
	{
		return;
	}
	if (mVOSkyp)
	{
		mVOSkyp->updateSky();
	}
}


void LLSky::setFogRatio(const F32 fog_ratio)
{
	if (mVOSkyp)
	{
		mVOSkyp->setFogRatio(fog_ratio);
	}
}


F32 LLSky::getFogRatio() const
{
	if (mVOSkyp)
	{
		return mVOSkyp->getFogRatio();
	}
	else
	{
		return 0.f;
	}
}


// Returns angle (DEGREES) between the horizontal plane and "v", 
// where the angle is negative when v.mV[VZ] < 0.0f
F32 elevation_from_vector(const LLVector3 &v)
{
	F32 elevation = 0.0f;
	F32 xy_component = (F32) sqrt(v.mV[VX] * v.mV[VX] + v.mV[VY] * v.mV[VY]);
	if (xy_component != 0.0f)
	{
		elevation = RAD_TO_DEG * (F32) atan(v.mV[VZ]/xy_component);
	}
	else
	{
		if (v.mV[VZ] > 0.f)
		{
			elevation = 90.f;
		}
		else
		{
			elevation = -90.f;
		}
	}
	return elevation;
}