/*
===========================================================================
Copyright (C) 2024 Gian 'myT' Schellenbaum

This file is part of Challenge Quake 3 (CNQ3).

Challenge Quake 3 is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.

Challenge Quake 3 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with Challenge Quake 3. If not, see <https://www.gnu.org/licenses/>.
===========================================================================
*/
// Cinematic Rendering Pipeline - sunlight on opaque surfaces


#include "crp_local.h"
#include "compshaders/crp/fullscreen.h"
#include "compshaders/crp/sun_visibility.h"
#include "compshaders/crp/sun_blur.h"


#pragma pack(push, 4)
struct SunBlurRC
{
	uint32_t visibilityTextureIndex;
	uint32_t penumbraTextureIndex;
};
#pragma pack(pop)


void Sunlight::Init()
{
	if(!rhiInfo.hasInlineRaytracing)
	{
		return;
	}

	{
		GraphicsPipelineDesc desc("Sunlight Visibility");
		MakeFullScreenPipeline(desc, ShaderByteCode(g_sun_visibility_ps));
		desc.AddRenderTarget(0, TextureFormat::R8_UNorm);
		desc.AddRenderTarget(0, TextureFormat::R8_UNorm);
		visibilityPipeline = CreateGraphicsPipeline(desc);
	}

	{
		GraphicsPipelineDesc desc("Sunlight Blur");
		MakeFullScreenPipeline(desc, ShaderByteCode(g_sun_blur_ps));
		desc.AddRenderTarget(0, crp.renderTargetFormat);
		blurPipeline = CreateGraphicsPipeline(desc);
	}

	{
		TextureDesc desc("sunlight visibility", glConfig.vidWidth, glConfig.vidHeight);
		desc.shortLifeTime = true;
		desc.format = TextureFormat::R8_UNorm;
		desc.initialState = ResourceStates::RenderTargetBit;
		desc.allowedState = ResourceStates::RenderTargetBit | ResourceStates::PixelShaderAccessBit | ResourceStates::ComputeShaderAccessBit;		
		visibilityTexture = CreateTexture(desc);
		desc.name = "sunlight penumbra";
		penumbraTexture = CreateTexture(desc);
	}
}

void Sunlight::Draw()
{
	if(crp_sunlight->integer == 0 ||
		(backEnd.refdef.rdflags & RDF_NOWORLDMODEL) != 0 ||
		!crp.raytracing.CanRaytrace() ||
		!IsViewportFullscreen(backEnd.viewParms))
	{
		CmdBeginBarrier();
		CmdTextureBarrier(crp.sunlightTexture, ResourceStates::RenderTargetBit);
		CmdEndBarrier();
		CmdClearColorTarget(crp.sunlightTexture, colorBlack);
		return;
	}

	srp.renderMode = RenderMode::None;

	{
		SCOPED_RENDER_PASS("Sunlight Visibility", 1.0f, 1.0f, 1.0f);

		CmdSetViewportAndScissor(0, 0, glConfig.vidWidth, glConfig.vidHeight);

		CmdBeginBarrier();
		CmdTextureBarrier(crp.shadingPositionTexture, ResourceStates::PixelShaderAccessBit);
		CmdTextureBarrier(visibilityTexture, ResourceStates::RenderTargetBit);
		CmdTextureBarrier(penumbraTexture, ResourceStates::RenderTargetBit);
		CmdEndBarrier();

		const HTexture renderTargets[] = { visibilityTexture, penumbraTexture };
		CmdBindRenderTargets(ARRAY_LEN(renderTargets), renderTargets, NULL);
		CmdBindPipeline(visibilityPipeline);
		CmdDraw(3, 0);
	}

	{
		SCOPED_RENDER_PASS("Sunlight Blur", 1.0f, 1.0f, 1.0f);

		CmdSetViewportAndScissor(0, 0, glConfig.vidWidth, glConfig.vidHeight);

		CmdBeginBarrier();
		for(int c = 0; c < 4; c++)
		{
			CmdTextureBarrier(crp.volumetricLight.sunShadowTextures[c], ResourceStates::PixelShaderAccessBit);
		}
		CmdTextureBarrier(visibilityTexture, ResourceStates::PixelShaderAccessBit);
		CmdTextureBarrier(penumbraTexture, ResourceStates::PixelShaderAccessBit);
		CmdTextureBarrier(crp.shadingPositionTexture, ResourceStates::PixelShaderAccessBit);
		CmdTextureBarrier(crp.normalTexture, ResourceStates::PixelShaderAccessBit);
		CmdTextureBarrier(crp.sunlightTexture, ResourceStates::RenderTargetBit);
		CmdEndBarrier();

		SunBlurRC rc = {};
		rc.penumbraTextureIndex = GetTextureIndexSRV(penumbraTexture);
		rc.visibilityTextureIndex = GetTextureIndexSRV(visibilityTexture);

		CmdBindRenderTargets(1, &crp.sunlightTexture, NULL);
		CmdBindPipeline(blurPipeline);
		CmdSetGraphicsRootConstants(0, sizeof(rc), &rc);
		CmdDraw(3, 0);
	}
}

bool Sunlight::WantRTASUpdate(const trRefdef_t& scene)
{
	return crp_sunlight->integer != 0;
}