// 
//---------------------------------------------------------------------------
//
// 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 "gi.h"
#include "build.h"
#include "v_draw.h"
//#include "a_dynlight.h"
#include "v_video.h"
#include "m_png.h"
//#include "doomstat.h"
//#include "r_data/r_interpolate.h"
//#include "r_utility.h"
//#include "d_player.h"
#include "i_time.h"
#include "hw_dynlightdata.h"
#include "hw_clock.h"
#include "flatvertices.h"
//#include "v_palette.h"
//#include "d_main.h"

#include "hw_renderstate.h"
#include "hw_lightbuffer.h"
#include "hw_cvars.h"
#include "hw_viewpointbuffer.h"
#include "hw_clipper.h"
//#include "hwrenderer/scene/hw_portal.h"
#include "hw_vrmodes.h"
//#include "g_levellocals.h"

#include "hw_drawstructs.h"
#include "hw_drawlist.h"
#include "hw_drawinfo.h"
#include "gamecvars.h"

EXTERN_CVAR(Bool, cl_capfps)
bool NoInterpolateView;


PalEntry GlobalMapFog;
float GlobalFogDensity;


#if 0
void CollectLights(FLevelLocals* Level)
{
	IShadowMap* sm = &screen->mShadowMap;
	int lightindex = 0;

	// Todo: this should go through the blockmap in a spiral pattern around the player so that closer lights are preferred.
	for (auto light = Level->lights; light; light = light->next)
	{
		IShadowMap::LightsProcessed++;
		if (light->shadowmapped && light->IsActive() && lightindex < 1024)
		{
			IShadowMap::LightsShadowmapped++;

			light->mShadowmapIndex = lightindex;
			sm->SetLight(lightindex, (float)light->X(), (float)light->Y(), (float)light->Z(), light->GetRadius());
			lightindex++;
		}
		else
		{
			light->mShadowmapIndex = 1024;
		}

	}

	for (; lightindex < 1024; lightindex++)
	{
		sm->SetLight(lightindex, 0, 0, 0, 0);
	}
}
#endif


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

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

	/*
	if (mainview && toscreen)
	{
		screen->SetAABBTree(camera->Level->aabbTree);
		screen->mShadowMap.SetCollectLights([=] {
			CollectLights(camera->Level);
		});
		screen->UpdateShadowMap();
	}
	*/

	// 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(nullptr, mainvp, nullptr);
		auto& vp = di->Viewpoint;
		vp = mainvp;

		di->Set3DViewport(RenderState);
		float flash = 1.f;
		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(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_DEFAULT, flash, [&]() { });
			PostProcess.Unclock();
		}
		di->EndDrawInfo();
		if (eyeCount - eye_ix > 1)
			screen->NextEye(eyeCount);
	}
}

//===========================================================================
//
// Set up the view point.
//
//===========================================================================

FRenderViewpoint SetupView(vec3_t& position, int sectnum, fixed_t q16angle, fixed_t q16horizon, float rollang)
{
	FRenderViewpoint r_viewpoint{};
	r_viewpoint.SectNum = sectnum;
	r_viewpoint.Pos = { position.x / 16.f, position.y / -16.f, position.z / -256.f };
	r_viewpoint.HWAngles.Yaw = -90.f + q16ang(q16angle).asdeg();
	r_viewpoint.HWAngles.Pitch = -HorizToPitch(q16horizon);
	r_viewpoint.HWAngles.Roll = -rollang;
	r_viewpoint.FieldOfView = (float)r_fov;
	r_viewpoint.RotAngle = q16ang(q16angle).asbam();
	return r_viewpoint;
}


void DoWriteSavePic(FileWriter* file, uint8_t* scr, int width, int height, bool upsidedown)
{
	int pixelsize = 1;

	int pitch = width * pixelsize;
	if (upsidedown)
	{
		scr += ((height - 1) * width * pixelsize);
		pitch *= -1;
	}

	M_CreatePNG(file, scr, nullptr, SS_RGB, width, height, pitch, vid_gamma);
}

//===========================================================================
//
// Render the view to a savegame picture
//
//===========================================================================

#if 0
void WriteSavePic(player_t* player, FileWriter* file, int width, int height)
{
	IntRect bounds;
	bounds.left = 0;
	bounds.top = 0;
	bounds.width = width;
	bounds.height = height;
	auto& RenderState = *screen->RenderState();

	// we must be sure the GPU finished reading from the buffer before we fill it with new data.
	screen->WaitForCommands(false);

	// Switch to render buffers dimensioned for the savepic
	screen->SetSaveBuffers(true);
	screen->ImageTransitionScene(true);

	hw_ClearFakeFlat();
	RenderState.SetVertexBuffer(screen->mVertexData);
	screen->mVertexData->Reset();
	screen->mLights->Clear();
	screen->mViewpoints->Clear();

	// This shouldn't overwrite the global viewpoint even for a short time.
	FRenderViewpoint savevp;
	sector_t* viewsector = RenderViewpoint(savevp, players[consoleplayer].camera, &bounds, r_viewpoint.FieldOfView.Degrees, 1.6f, 1.6f, true, false);
	RenderState.EnableStencil(false);
	RenderState.SetNoSoftLightLevel();

	int numpixels = width * height;
	uint8_t* scr = (uint8_t*)M_Malloc(numpixels * 3);
	screen->CopyScreenToBuffer(width, height, scr);

	DoWriteSavePic(file, SS_RGB, scr, width, height, viewsector, screen->FlipSavePic());
	M_Free(scr);

	// Switch back the screen render buffers
	screen->SetViewportRects(nullptr);
	screen->SetSaveBuffers(false);
}
#endif

//===========================================================================
//
// Renders the main view
//
//===========================================================================

static void CheckTimer(FRenderState &state, uint64_t ShaderStartTime)
{
	// if firstFrame is not yet initialized, initialize it to current time
	// if we're going to overflow a float (after ~4.6 hours, or 24 bits), re-init to regain precision
	if ((state.firstFrame == 0) || (screen->FrameTime - state.firstFrame >= 1 << 24) || ShaderStartTime >= state.firstFrame)
		state.firstFrame = screen->FrameTime;
}


void render_drawrooms(vec3_t& position, int sectnum, fixed_t q16angle, fixed_t q16horizon, float rollang, bool mirror, bool planemirror)
{
	auto RenderState = screen->RenderState();
	RenderState->SetVertexBuffer(screen->mVertexData);
	screen->mVertexData->Reset();

	FRenderViewpoint r_viewpoint = SetupView(position, sectnum, q16angle, q16horizon, rollang);
	iter_dlightf = iter_dlight = draw_dlight = draw_dlightf = 0;

	checkBenchActive();

	// reset statistics counters
	ResetProfilingData();

	// Get this before everything else
	if (cl_capfps) r_viewpoint.TicFrac = 1.;
	else r_viewpoint.TicFrac = I_GetTimeFrac();

	screen->mLights->Clear();
	screen->mViewpoints->Clear();

	// NoInterpolateView should have no bearing on camera textures, but needs to be preserved for the main view below.
	bool saved_niv = NoInterpolateView;
	NoInterpolateView = false;

	// Shader start time does not need to be handled per level. Just use the one from the camera to render from.
	CheckTimer(*RenderState, 0/*ShaderStartTime*/);
	// prepare all camera textures that have been used in the last frame.
	// This must be done for all levels, not just the primary one!
	/*
	Level->canvasTextureInfo.UpdateAll([&](AActor* camera, FCanvasTexture* camtex, double fov)
		{
			screen->RenderTextureView(camtex, [=](IntRect& bounds)
				{
					FRenderViewpoint texvp;
					float ratio = camtex->aspectRatio;
					RenderViewpoint(texvp, camera, &bounds, fov, ratio, ratio, false, false);
				});
		});
	}
	*/
	NoInterpolateView = saved_niv;

	// now render the main view
	float fovratio;
	float ratio = ActiveRatio(windowxy2.x - windowxy1.x + 1, windowxy2.y - windowxy1.y + 1);
	if (ratio >= 1.33f)
	{
		fovratio = 1.33f;
	}
	else
	{
		fovratio = ratio;
	}

	screen->ImageTransitionScene(true); // Only relevant for Vulkan.

	RenderViewpoint(r_viewpoint, NULL, r_viewpoint.FieldOfView.Degrees, ratio, fovratio, true, true);
	All.Unclock();
}