source/graphics/ShaderManager.h

   1 /* Copyright (C) 2023 Wildfire Games.
   2  * This file is part of 0 A.D.
   3  *
   4  * 0 A.D. is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * 0 A.D. is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #ifndef INCLUDED_SHADERMANAGER
  19 #define INCLUDED_SHADERMANAGER
  20
  21 #include "graphics/ShaderDefines.h"
  22 #include "graphics/ShaderProgram.h"
  23 #include "graphics/ShaderTechnique.h"
  24 #include "renderer/backend/PipelineState.h"
  25
  26 #include <functional>
  27 #include <memory>
  28 #include <set>
  29 #include <unordered_map>
  30
  31 /**
  32  * Shader manager: loads and caches shader programs.
  33  *
  34  * For a high-level overview of shaders and materials, see
  35  * http://trac.wildfiregames.com/wiki/MaterialSystem
  36  */
  37 class CShaderManager
  38 {
  39 public:
  40         CShaderManager(Renderer::Backend::IDevice* device);
  41         ~CShaderManager();
  42
  43         /**
  44          * Load a shader effect.
  45          * Effects can be implemented via many techniques; this returns the best usable technique.
  46          * @param name name of effect XML specification (file is loaded from shaders/effects/${name}.xml)
  47          * @param defines key/value set of preprocessor definitions
  48          * @return loaded technique, or empty technique on error
  49          */
  50         CShaderTechniquePtr LoadEffect(CStrIntern name, const CShaderDefines& defines);
  51
  52         /**
  53          * Load a shader effect, with empty defines.
  54          */
  55         CShaderTechniquePtr LoadEffect(CStrIntern name);
  56
  57         /**
  58          * Load a shader effect with the pipeline state description overwriting.
  59          * TODO: we should set all needed states in XML.
  60          */
  61         using PipelineStateDescCallback = CShaderTechnique::PipelineStateDescCallback;
  62         CShaderTechniquePtr LoadEffect(
  63                 CStrIntern name, const CShaderDefines& defines, const PipelineStateDescCallback& callback);
  64
  65         /**
  66          * Returns the number of shader effects that are currently loaded.
  67          */
  68         size_t GetNumEffectsLoaded() const;
  69
  70 private:
  71         struct CacheKey
  72         {
  73                 std::string name;
  74                 CShaderDefines defines;
  75
  76                 bool operator<(const CacheKey& k) const
  77                 {
  78                         if (name < k.name) return true;
  79                         if (k.name < name) return false;
  80                         return defines < k.defines;
  81                 }
  82         };
  83
  84         Renderer::Backend::IDevice* m_Device = nullptr;
  85
  86         // A CShaderProgram contains expensive backend state, so we ought to cache it.
  87         // The compiled state depends solely on the filename and list of defines,
  88         // so we store that in CacheKey.
  89         // TODO: is this cache useful when we already have an effect cache?
  90         std::map<CacheKey, CShaderProgramPtr> m_ProgramCache;
  91
  92         /**
  93          * Key for effect cache lookups.
  94          * This stores two separate CShaderDefines because the renderer typically
  95          * has one set from the rendering context and one set from the material;
  96          * by handling both separately here, we avoid the cost of having to merge
  97          * the two sets into a single one before doing the cache lookup.
  98          */
  99         struct EffectCacheKey
 100         {
 101                 CStrIntern name;
 102                 CShaderDefines defines;
 103
 104                 bool operator==(const EffectCacheKey& b) const;
 105         };
 106
 107         struct EffectCacheKeyHash
 108         {
 109                 size_t operator()(const EffectCacheKey& key) const;
 110         };
 111
 112         using EffectCacheMap = std::unordered_map<EffectCacheKey, CShaderTechniquePtr, EffectCacheKeyHash>;
 113         EffectCacheMap m_EffectCache;
 114
 115         // Store the set of shaders that need to be reloaded when the given file is modified
 116         template<typename T>
 117         using HotloadFilesMap = std::unordered_map<
 118                 VfsPath,
 119                 std::set<std::weak_ptr<T>, std::owner_less<std::weak_ptr<T>>>>;
 120         HotloadFilesMap<CShaderTechnique> m_HotloadTechniques;
 121         HotloadFilesMap<CShaderProgram> m_HotloadPrograms;
 122
 123         /**
 124          * Load a shader program.
 125          * @param name name of shader XML specification (file is loaded from shaders/${name}.xml)
 126          * @param defines key/value set of preprocessor definitions
 127          * @return loaded program, or null pointer on error
 128          */
 129         CShaderProgramPtr LoadProgram(const CStr& name, const CShaderDefines& defines);
 130
 131         bool LoadTechnique(CShaderTechniquePtr& tech);
 132
 133         static Status ReloadChangedFileCB(void* param, const VfsPath& path);
 134         Status ReloadChangedFile(const VfsPath& path);
 135
 136         /**
 137          * Associates the file with the technique to be reloaded if the file has changed.
 138          */
 139         void AddTechniqueFileDependency(const CShaderTechniquePtr& technique, const VfsPath& path);
 140
 141         /**
 142          * Associates the file with the program to be reloaded if the file has changed.
 143          */
 144         void AddProgramFileDependency(const CShaderProgramPtr& program, const VfsPath& path);
 145 };
 146
 147 #endif // INCLUDED_SHADERMANAGER