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https://github.com/ZDoom/qzdoom.git
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163 lines
5.3 KiB
C++
163 lines
5.3 KiB
C++
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//
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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 "hwrenderer/dynlights/hw_shadowmap.h"
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#include "hwrenderer/utility/hw_cvars.h"
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#include "hwrenderer/dynlights/hw_dynlightdata.h"
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#include "stats.h"
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#include "g_levellocals.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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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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CUSTOM_CVAR (Bool, gl_light_shadowmap, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)
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{
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if (!self)
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{
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// Unset any residual shadow map indices in the light actors.
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TThinkerIterator<ADynamicLight> it(STAT_DLIGHT);
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while (auto light = it.Next())
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{
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light->mShadowmapIndex = 1024;
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}
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}
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}
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bool IShadowMap::ShadowTest(ADynamicLight *light, const DVector3 &pos)
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{
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if (light->shadowmapped && light->radius > 0.0 && IsEnabled() && mAABBTree)
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return mAABBTree->RayTest(light->Pos(), pos) >= 1.0f;
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else
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return true;
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}
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bool IShadowMap::IsEnabled() const
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{
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return gl_light_shadowmap && (screen->hwcaps & RFL_SHADER_STORAGE_BUFFER);
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}
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void IShadowMap::CollectLights()
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{
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if (mLights.Size() != 1024 * 4) mLights.Resize(1024 * 4);
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int lightindex = 0;
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// Todo: this should go through the blockmap in a spiral pattern around the player so that closer lights are preferred.
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TThinkerIterator<ADynamicLight> it(STAT_DLIGHT);
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while (auto light = it.Next())
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{
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LightsProcessed++;
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if (light->shadowmapped && light->IsActive() && lightindex < 1024 * 4)
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{
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LightsShadowmapped++;
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light->mShadowmapIndex = lightindex >> 2;
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mLights[lightindex] = (float)light->X();
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mLights[lightindex+1] = (float)light->Y();
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mLights[lightindex+2] = (float)light->Z();
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mLights[lightindex+3] = light->GetRadius();
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lightindex += 4;
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}
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else
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{
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light->mShadowmapIndex = 1024;
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}
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}
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for (; lightindex < 1024 * 4; lightindex++)
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{
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mLights[lightindex] = 0;
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}
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}
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bool IShadowMap::ValidateAABBTree()
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{
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// Just comparing the level info is not enough. If two MAPINFO-less levels get played after each other,
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// they can both refer to the same default level info.
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if (level.info != mLastLevel && (level.nodes.Size() != mLastNumNodes || level.segs.Size() != mLastNumSegs))
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{
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mAABBTree.reset();
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mLastLevel = level.info;
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mLastNumNodes = level.nodes.Size();
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mLastNumSegs = level.segs.Size();
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}
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if (mAABBTree)
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return true;
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mAABBTree.reset(new hwrenderer::LevelAABBTree());
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return false;
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}
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