source/renderer/ShadowMap.h

   1 /* Copyright (C) 2012 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 /*
  19  * Shadow mapping related texture and matrix management
  20  */
  21
  22 #ifndef INCLUDED_SHADOWMAP
  23 #define INCLUDED_SHADOWMAP
  24
  25 #include "lib/ogl.h"
  26
  27 class CBoundingBoxAligned;
  28 class CMatrix3D;
  29
  30 struct ShadowMapInternals;
  31
  32 /**
  33  * Class ShadowMap: Maintain the shadow map texture and perform necessary OpenGL setup,
  34  * including matrix calculations.
  35  *
  36  * The class will automatically generate a texture the first time the shadow map is rendered into.
  37  * The texture will not be resized afterwards.
  38  */
  39 class ShadowMap
  40 {
  41 public:
  42         ShadowMap();
  43         ~ShadowMap();
  44
  45         /**
  46          * RecreateTexture: Destroy the current shadow texture and force creation of
  47          * a new one. Useful when the renderer's size has changed and the texture
  48          * should be resized too.
  49          */
  50         void RecreateTexture();
  51
  52         /**
  53          * GetDepthTextureBits: Return the number of bits to use for depth textures when
  54          * enabled.
  55          *
  56          * @return depth texture bit depth
  57          */
  58         int GetDepthTextureBits() const;
  59
  60         /**
  61          * SetDepthTextureBits: Sets the number of bits to use for depth textures when enabled.
  62          * Possible values are 16, 24, 32 and 0 (= use default)
  63          *
  64          * @param bits number of bits
  65          */
  66         void SetDepthTextureBits(int bits);
  67
  68         /**
  69          * GetWidth: Return the width of the depth texture.
  70          *
  71          * @return depth texture width
  72          */
  73         int GetWidth() const;
  74
  75         /**
  76          * GetHeight: Return the height of the depth texture
  77          *
  78          * @return depth texture height
  79          */
  80         int GetHeight() const;
  81
  82         /**
  83          * SetupFrame: Configure light space for the given camera and light direction,
  84          * create the shadow texture if necessary, etc.
  85          *
  86          * @param camera the camera that will be used for world rendering
  87          * @param lightdir the direction of the (directional) sunlight
  88          */
  89         void SetupFrame(const CCamera& camera, const CVector3D& lightdir);
  90
  91         /**
  92          * Add the bounding box of an object that will cast a shadow.
  93          * This is used to calculate the bounds for the shadow map.
  94          *
  95          * @param bounds world space bounding box
  96          */
  97         void AddShadowCasterBound(const CBoundingBoxAligned& bounds);
  98
  99         /**
 100          * Add the bounding box of an object that will receive a shadow.
 101          * This is used to calculate the bounds for the shadow map.
 102          *
 103          * @param bounds world space bounding box
 104          */
 105         void AddShadowReceiverBound(const CBoundingBoxAligned& bounds);
 106
 107         /**
 108          * Compute the frustum originating at the light source, that encompasses
 109          * all the objects passed into AddShadowReceiverBound so far.
 110          *
 111          * This frustum can be used to determine which objects might cast a visible
 112          * shadow. Those objects should be passed to AddShadowCasterBound and
 113          * then should be rendered into the shadow map.
 114          */
 115         CFrustum GetShadowCasterCullFrustum();
 116
 117         /**
 118          * BeginRender: Set OpenGL state for rendering into the shadow map texture.
 119          *
 120          * @todo this depends in non-obvious ways on the behaviour of the call-site
 121          */
 122         void BeginRender();
 123
 124         /**
 125          * EndRender: Finish rendering into the shadow map.
 126          *
 127          * @todo this depends in non-obvious ways on the behaviour of the call-site
 128          */
 129         void EndRender();
 130
 131         /**
 132          * GetTexture: Retrieve the OpenGL texture object name that contains the shadow map.
 133          *
 134          * @return the texture name of the shadow map texture
 135          */
 136         GLuint GetTexture() const;
 137
 138         /**
 139          * GetTextureMatrix: Retrieve the world-space to shadow map texture coordinates
 140          * transformation matrix.
 141          *
 142          * @return the matrix that transforms world-space coordinates into homogenous
 143          * shadow map texture coordinates
 144          */
 145         const CMatrix3D& GetTextureMatrix() const;
 146
 147         /**
 148          * Visualize shadow mapping calculations to help in
 149          * debugging and optimal shadow map usage.
 150          */
 151         void RenderDebugBounds();
 152
 153         /**
 154          * Visualize shadow map texture to help in debugging.
 155          */
 156         void RenderDebugTexture();
 157
 158 private:
 159         ShadowMapInternals* m;
 160 };
 161
 162 #endif // INCLUDED_SHADOWMAP