source/graphics/Camera.h

   1 /* Copyright (C) 2013 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  * CCamera holds a view and a projection matrix. It also has a frustum
  20  * which can be used to cull objects for rendering.
  21  */
  22
  23 #ifndef INCLUDED_CAMERA
  24 #define INCLUDED_CAMERA
  25
  26 #include "Frustum.h"
  27 #include "maths/BoundingBoxAligned.h"
  28 #include "maths/Matrix3D.h"
  29
  30 // view port
  31 struct SViewPort
  32 {
  33         int m_X;
  34         int m_Y;
  35         int m_Width;
  36         int m_Height;
  37 };
  38
  39 class CCamera
  40 {
  41         public:
  42                 CCamera();
  43                 ~CCamera();
  44
  45                 // Methods for projection
  46                 void SetProjection(float nearp, float farp, float fov);
  47                 void SetProjection(const CMatrix3D& matrix) { m_ProjMat = matrix; }
  48                 void SetProjectionTile(int tiles, int tile_x, int tile_y);
  49                 CMatrix3D& GetProjection() { return m_ProjMat; }
  50                 const CMatrix3D& GetProjection() const { return m_ProjMat; }
  51
  52                 CMatrix3D& GetOrientation() { return m_Orientation; }
  53                 const CMatrix3D& GetOrientation() const { return m_Orientation; }
  54
  55                 CMatrix3D GetViewProjection() const { return m_ProjMat * m_Orientation.GetInverse(); }
  56
  57                 // Updates the frustum planes. Should be called
  58                 // everytime the view or projection matrices are
  59                 // altered.
  60                 void UpdateFrustum(const CBoundingBoxAligned& scissor = CBoundingBoxAligned(CVector3D(-1.0f, -1.0f, -1.0f), CVector3D(1.0f, 1.0f, 1.0f)));
  61                 void ClipFrustum(const CPlane& clipPlane);
  62                 const CFrustum& GetFrustum() const { return m_ViewFrustum; }
  63
  64                 void SetViewPort(const SViewPort& viewport);
  65                 const SViewPort& GetViewPort() const { return m_ViewPort; }
  66
  67                 // getters
  68                 float GetNearPlane() const { return m_NearPlane; }
  69                 float GetFarPlane() const { return m_FarPlane; }
  70                 float GetFOV() const { return m_FOV; }
  71
  72                 // return four points in camera space at given distance from camera
  73                 void GetCameraPlanePoints(float dist,CVector3D pts[4]) const;
  74
  75                 // Build a ray passing through the screen coordinate (px, py) and the camera
  76                 /////////////////////////////////////////////////////////////////////////////////////////
  77                 // BuildCameraRay: calculate origin and ray direction of a ray through
  78                 // the pixel (px,py) on the screen
  79                 void BuildCameraRay(int px, int py, CVector3D& origin, CVector3D& dir) const;
  80
  81                 // General helpers that seem to fit here
  82
  83                 // Get the screen-space coordinates corresponding to a given world-space position
  84                 void GetScreenCoordinates(const CVector3D& world, float& x, float& y) const;
  85
  86                 // Get the point on the terrain corresponding to pixel (px,py) (or the mouse coordinates)
  87                 // The aboveWater parameter determines whether we want to stop at the water plane or also get underwater points
  88                 CVector3D GetWorldCoordinates(int px, int py, bool aboveWater=false) const;
  89                 // Get the point on the plane at height h corresponding to pixel (px,py)
  90                 CVector3D GetWorldCoordinates(int px, int py, float h) const;
  91                 // Get the point on the terrain (or water plane) the camera is pointing towards
  92                 CVector3D GetFocus() const;
  93
  94                 // Build an orientation matrix from camera position, camera focus point, and up-vector
  95                 void LookAt(const CVector3D& camera, const CVector3D& orientation, const CVector3D& up);
  96
  97                 // Build an orientation matrix from camera position, camera orientation, and up-vector
  98                 void LookAlong(CVector3D camera, CVector3D focus, CVector3D up);
  99
 100                 /**
 101                  * Render: Renders the camera's frustum in world space.
 102                  * The caller should set the color using glColorXy before calling Render.
 103                  *
 104                  * @param intermediates determines how many intermediate distance planes should
 105                  * be hinted at between the near and far planes
 106                  */
 107                 void Render(int intermediates = 0) const;
 108
 109         public:
 110                 // This is the orientation matrix. The inverse of this
 111                 // is the view matrix
 112                 CMatrix3D               m_Orientation;
 113
 114                 // Should not be tweaked externally if possible
 115                 CMatrix3D               m_ProjMat;
 116
 117         private:
 118                 float                   m_NearPlane;
 119                 float                   m_FarPlane;
 120                 float                   m_FOV;
 121                 SViewPort               m_ViewPort;
 122
 123                 CFrustum                m_ViewFrustum;
 124 };
 125
 126 #endif