source/graphics/Camera.h

   1 /* Copyright (C) 2021 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 "maths/BoundingBoxAligned.h"
  27 #include "maths/Frustum.h"
  28 #include "maths/Matrix3D.h"
  29
  30 #include <array>
  31
  32 // view port
  33 struct SViewPort
  34 {
  35         int m_X;
  36         int m_Y;
  37         int m_Width;
  38         int m_Height;
  39 };
  40
  41 class CCamera
  42 {
  43         public:
  44                 // Represents camera viewport or frustum side in 3D space.
  45                 using Quad = std::array<CVector3D, 4>;
  46
  47                 enum class ProjectionType
  48                 {
  49                         CUSTOM,
  50                         ORTHO,
  51                         PERSPECTIVE,
  52                 };
  53
  54                 CCamera();
  55                 ~CCamera();
  56
  57                 CMatrix3D& GetProjection() { return m_ProjMat; }
  58                 const CMatrix3D& GetProjection() const { return m_ProjMat; }
  59                 CMatrix3D GetViewProjection() const { return m_ProjMat * m_Orientation.GetInverse(); }
  60                 void SetProjection(const CMatrix3D& matrix);
  61                 void SetProjectionFromCamera(const CCamera& camera);
  62                 void SetOrthoProjection(float nearp, float farp, float scale);
  63                 void SetPerspectiveProjection(float nearp, float farp, float fov);
  64                 ProjectionType GetProjectionType() const { return m_ProjType; }
  65
  66                 CMatrix3D& GetOrientation() { return m_Orientation; }
  67                 const CMatrix3D& GetOrientation() const { return m_Orientation; }
  68
  69                 // Updates the frustum planes. Should be called
  70                 // everytime the view or projection matrices are
  71                 // altered.
  72                 void UpdateFrustum(const CBoundingBoxAligned& scissor = CBoundingBoxAligned(CVector3D(-1.0f, -1.0f, -1.0f), CVector3D(1.0f, 1.0f, 1.0f)));
  73                 void ClipFrustum(const CPlane& clipPlane);
  74                 const CFrustum& GetFrustum() const { return m_ViewFrustum; }
  75
  76                 void SetViewPort(const SViewPort& viewport);
  77                 const SViewPort& GetViewPort() const { return m_ViewPort; }
  78                 float GetAspectRatio() const;
  79
  80                 float GetNearPlane() const { return m_NearPlane; }
  81                 float GetFarPlane() const { return m_FarPlane; }
  82                 float GetFOV() const { return m_FOV; }
  83                 float GetOrthoScale() const { return m_OrthoScale; }
  84
  85                 // Returns a quad of view in camera space at given distance from camera.
  86                 void GetViewQuad(float dist, Quad& quad) const;
  87
  88                 // Builds a ray passing through the screen coordinate (px, py), calculates
  89                 // origin and direction of the ray.
  90                 void BuildCameraRay(int px, int py, CVector3D& origin, CVector3D& dir) const;
  91
  92                 // General helpers that seem to fit here
  93
  94                 // Get the screen-space coordinates corresponding to a given world-space position
  95                 void GetScreenCoordinates(const CVector3D& world, float& x, float& y) const;
  96
  97                 // Get the point on the terrain corresponding to pixel (px,py) (or the mouse coordinates)
  98                 // The aboveWater parameter determines whether we want to stop at the water plane or also get underwater points
  99                 CVector3D GetWorldCoordinates(int px, int py, bool aboveWater=false) const;
 100                 // Get the point on the plane at height h corresponding to pixel (px,py)
 101                 CVector3D GetWorldCoordinates(int px, int py, float h) const;
 102                 // Get the point on the terrain (or water plane) the camera is pointing towards
 103                 CVector3D GetFocus() const;
 104
 105                 CBoundingBoxAligned GetBoundsInViewPort(const CBoundingBoxAligned& boundigBox) const;
 106
 107                 // Build an orientation matrix from camera position, camera focus point, and up-vector
 108                 void LookAt(const CVector3D& camera, const CVector3D& focus, const CVector3D& up);
 109
 110                 // Build an orientation matrix from camera position, camera orientation, and up-vector
 111                 void LookAlong(const CVector3D& camera, CVector3D orientation, CVector3D up);
 112
 113         public:
 114                 // This is the orientation matrix. The inverse of this
 115                 // is the view matrix
 116                 CMatrix3D m_Orientation;
 117
 118         private:
 119                 CMatrix3D m_ProjMat;
 120                 ProjectionType m_ProjType = ProjectionType::CUSTOM;
 121
 122                 float m_NearPlane = 0.0f;
 123                 float m_FarPlane = 0.0f;
 124                 union
 125                 {
 126                         float m_FOV;
 127                         float m_OrthoScale;
 128                 };
 129                 SViewPort m_ViewPort;
 130
 131                 CFrustum m_ViewFrustum;
 132 };
 133
 134 #endif // INCLUDED_CAMERA