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155 lines
4.9 KiB
C++
155 lines
4.9 KiB
C++
//
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//---------------------------------------------------------------------------
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// 1D dynamic shadow maps (API independent part)
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// Copyright(C) 2017 Magnus Norddahl
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// All rights reserved.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with this program. If not, see http://www.gnu.org/licenses/
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//
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//--------------------------------------------------------------------------
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//
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#include "hw_shadowmap.h"
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#include "hw_cvars.h"
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#include "hw_dynlightdata.h"
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#include "buffers.h"
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#include "shaderuniforms.h"
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#include "hwrenderer/postprocessing/hw_postprocess.h"
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/*
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The 1D shadow maps are stored in a 1024x1024 texture as float depth values (R32F).
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Each line in the texture is assigned to a single light. For example, to grab depth values for light 20
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the fragment shader (main.fp) needs to sample from row 20. That is, the V texture coordinate needs
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to be 20.5/1024.
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The texel row for each light is split into four parts. One for each direction, like a cube texture,
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but then only in 2D where this reduces itself to a square. When main.fp samples from the shadow map
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it first decides in which direction the fragment is (relative to the light), like cubemap sampling does
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for 3D, but once again just for the 2D case.
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Texels 0-255 is Y positive, 256-511 is X positive, 512-767 is Y negative and 768-1023 is X negative.
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Generating the shadow map itself is done by FShadowMap::Update(). The shadow map texture's FBO is
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bound and then a screen quad is drawn to make a fragment shader cover all texels. For each fragment
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it shoots a ray and collects the distance to what it hit.
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The shadowmap.fp shader knows which light and texel it is processing by mapping gl_FragCoord.y back
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to the light index, and it knows which direction to ray trace by looking at gl_FragCoord.x. For
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example, if gl_FragCoord.y is 20.5, then it knows its processing light 20, and if gl_FragCoord.x is
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127.5, then it knows we are shooting straight ahead for the Y positive direction.
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Ray testing is done by uploading two GPU storage buffers - one holding AABB tree nodes, and one with
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the line segments at the leaf nodes of the tree. The fragment shader then performs a test same way
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as on the CPU, except everything uses indexes as pointers are not allowed in GLSL.
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*/
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cycle_t IShadowMap::UpdateCycles;
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int IShadowMap::LightsProcessed;
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int IShadowMap::LightsShadowmapped;
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CVAR(Bool, gl_light_shadowmap, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
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ADD_STAT(shadowmap)
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{
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FString out;
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out.Format("upload=%04.2f ms lights=%d shadowmapped=%d", IShadowMap::UpdateCycles.TimeMS(), IShadowMap::LightsProcessed, IShadowMap::LightsShadowmapped);
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return out;
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}
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CUSTOM_CVAR(Int, gl_shadowmap_quality, 512, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
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{
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switch (self)
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{
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case 128:
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case 256:
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case 512:
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case 1024:
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break;
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default:
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self = 128;
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break;
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}
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}
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bool IShadowMap::ShadowTest(const DVector3 &lpos, const DVector3 &pos)
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{
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if (mAABBTree && gl_light_shadowmap)
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return mAABBTree->RayTest(lpos, pos) >= 1.0f;
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else
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return true;
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}
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bool IShadowMap::PerformUpdate()
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{
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UpdateCycles.Reset();
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LightsProcessed = 0;
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LightsShadowmapped = 0;
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if (gl_light_shadowmap && (screen->hwcaps & RFL_SHADER_STORAGE_BUFFER) && CollectLights != nullptr)
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{
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UpdateCycles.Clock();
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UploadAABBTree();
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UploadLights();
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return true;
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}
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return false;
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}
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void IShadowMap::UploadLights()
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{
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mLights.Resize(1024 * 4);
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CollectLights();
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if (mLightList == nullptr)
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mLightList = screen->CreateDataBuffer(LIGHTLIST_BINDINGPOINT, true, false);
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mLightList->SetData(sizeof(float) * mLights.Size(), &mLights[0]);
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}
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void IShadowMap::UploadAABBTree()
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{
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if (mNewTree)
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{
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mNewTree = false;
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if (!mNodesBuffer)
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mNodesBuffer = screen->CreateDataBuffer(LIGHTNODES_BINDINGPOINT, true, false);
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mNodesBuffer->SetData(mAABBTree->NodesSize(), mAABBTree->Nodes());
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if (!mLinesBuffer)
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mLinesBuffer = screen->CreateDataBuffer(LIGHTLINES_BINDINGPOINT, true, false);
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mLinesBuffer->SetData(mAABBTree->LinesSize(), mAABBTree->Lines());
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}
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else if (mAABBTree->Update())
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{
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mNodesBuffer->SetSubData(mAABBTree->DynamicNodesOffset(), mAABBTree->DynamicNodesSize(), mAABBTree->DynamicNodes());
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mLinesBuffer->SetSubData(mAABBTree->DynamicLinesOffset(), mAABBTree->DynamicLinesSize(), mAABBTree->DynamicLines());
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}
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}
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void IShadowMap::Reset()
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{
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delete mLightList; mLightList = nullptr;
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delete mNodesBuffer; mNodesBuffer = nullptr;
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delete mLinesBuffer; mLinesBuffer = nullptr;
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}
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IShadowMap::~IShadowMap()
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{
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Reset();
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}
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