// 
//---------------------------------------------------------------------------
//
// Copyright(C) 2004-2016 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_scene.cpp
** manages the rendering of the player's view
**
*/

#include "gl_system.h"
#include "gi.h"
#include "m_png.h"
#include "doomstat.h"
#include "r_data/r_interpolate.h"
#include "r_utility.h"
#include "d_player.h"
#include "hwrenderer/dynlights/hw_dynlightdata.h"
#include "hwrenderer/utility/hw_clock.h"
#include "hwrenderer/data/flatvertices.h"

#include "hwrenderer/dynlights/hw_lightbuffer.h"
#include "hwrenderer/utility/hw_cvars.h"
#include "hwrenderer/data/hw_viewpointbuffer.h"
#include "hwrenderer/scene/hw_clipper.h"
#include "hwrenderer/scene/hw_portal.h"
#include "hwrenderer/utility/hw_vrmodes.h"


//-----------------------------------------------------------------------------
//
// Renders one viewpoint in a scene
//
//-----------------------------------------------------------------------------

sector_t* RenderViewpoint(FRenderViewpoint& mainvp, AActor* camera, IntRect* bounds, float fov, float ratio, float fovratio, bool mainview, bool toscreen)
{
	auto& RenderState = *screen->RenderState();

	R_SetupFrame(mainvp, r_viewwindow, camera);

	if (mainview && toscreen)
		screen->UpdateShadowMap();

	// Update the attenuation flag of all light defaults for each viewpoint.
	// This function will only do something if the setting differs.
	FLightDefaults::SetAttenuationForLevel(!!(camera->Level->flags3 & LEVEL3_ATTENUATE));

	// Render (potentially) multiple views for stereo 3d
	// Fixme. The view offsetting should be done with a static table and not require setup of the entire render state for the mode.
	auto vrmode = VRMode::GetVRMode(mainview && toscreen);
	const int eyeCount = vrmode->mEyeCount;
	screen->FirstEye();
	for (int eye_ix = 0; eye_ix < eyeCount; ++eye_ix)
	{
		const auto& eye = vrmode->mEyes[eye_ix];
		screen->SetViewportRects(bounds);

		if (mainview) // Bind the scene frame buffer and turn on draw buffers used by ssao
		{
			bool useSSAO = (gl_ssao != 0);
			screen->SetSceneRenderTarget(useSSAO);
			RenderState.SetPassType(useSSAO ? GBUFFER_PASS : NORMAL_PASS);
			RenderState.EnableDrawBuffers(RenderState.GetPassDrawBufferCount(), true);
		}

		auto di = HWDrawInfo::StartDrawInfo(mainvp.ViewLevel, nullptr, mainvp, nullptr);
		auto& vp = di->Viewpoint;

		di->Set3DViewport(RenderState);
		di->SetViewArea();
		auto cm = di->SetFullbrightFlags(mainview ? vp.camera->player : nullptr);
		di->Viewpoint.FieldOfView = fov;	// Set the real FOV for the current scene (it's not necessarily the same as the global setting in r_viewpoint)

		// Stereo mode specific perspective projection
		di->VPUniforms.mProjectionMatrix = eye.GetProjection(fov, ratio, fovratio);
		// Stereo mode specific viewpoint adjustment
		vp.Pos += eye.GetViewShift(vp.HWAngles.Yaw.Degrees);
		di->SetupView(RenderState, vp.Pos.X, vp.Pos.Y, vp.Pos.Z, false, false);

		di->ProcessScene(toscreen);

		if (mainview)
		{
			PostProcess.Clock();
			if (toscreen) di->EndDrawScene(mainvp.sector, RenderState); // do not call this for camera textures.

			if (RenderState.GetPassType() == GBUFFER_PASS) // Turn off ssao draw buffers
			{
				RenderState.SetPassType(NORMAL_PASS);
				RenderState.EnableDrawBuffers(1);
			}

			screen->PostProcessScene(false, cm, [&]() { di->DrawEndScene2D(mainvp.sector, RenderState); });
			PostProcess.Unclock();
		}
		di->EndDrawInfo();
		if (eyeCount - eye_ix > 1)
			screen->NextEye(eyeCount);
	}

	return mainvp.sector;
}