1 | /* Copyright (C) 2021 Wildfire Games.
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2 | * This file is part of 0 A.D.
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3 | *
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4 | * 0 A.D. is free software: you can redistribute it and/or modify
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5 | * it under the terms of the GNU General Public License as published by
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6 | * the Free Software Foundation, either version 2 of the License, or
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7 | * (at your option) any later version.
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8 | *
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9 | * 0 A.D. is distributed in the hope that it will be useful,
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10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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12 | * GNU General Public License for more details.
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13 | *
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14 | * You should have received a copy of the GNU General Public License
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15 | * along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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16 | */
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17 |
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18 | /*
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19 | * CCamera holds a view and a projection matrix. It also has a frustum
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20 | * which can be used to cull objects for rendering.
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21 | */
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22 |
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23 | #ifndef INCLUDED_CAMERA
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24 | #define INCLUDED_CAMERA
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25 |
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26 | #include "maths/BoundingBoxAligned.h"
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27 | #include "maths/Frustum.h"
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28 | #include "maths/Matrix3D.h"
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29 |
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30 | #include <array>
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31 |
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32 | // view port
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33 | struct SViewPort
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34 | {
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35 | int m_X;
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36 | int m_Y;
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37 | int m_Width;
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38 | int m_Height;
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39 | };
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40 |
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41 | class CCamera
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42 | {
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43 | public:
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44 | // Represents camera viewport or frustum side in 3D space.
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45 | using Quad = std::array<CVector3D, 4>;
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46 |
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47 | enum class ProjectionType
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48 | {
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49 | CUSTOM,
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50 | ORTHO,
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51 | PERSPECTIVE,
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52 | };
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53 |
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54 | CCamera();
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55 | ~CCamera();
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56 |
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57 | CMatrix3D& GetProjection() { return m_ProjMat; }
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58 | const CMatrix3D& GetProjection() const { return m_ProjMat; }
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59 | CMatrix3D GetViewProjection() const { return m_ProjMat * m_Orientation.GetInverse(); }
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60 | void SetProjection(const CMatrix3D& matrix);
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61 | void SetProjectionFromCamera(const CCamera& camera);
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62 | void SetOrthoProjection(float nearp, float farp, float scale);
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63 | void SetPerspectiveProjection(float nearp, float farp, float fov);
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64 | ProjectionType GetProjectionType() const { return m_ProjType; }
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65 |
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66 | CMatrix3D& GetOrientation() { return m_Orientation; }
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67 | const CMatrix3D& GetOrientation() const { return m_Orientation; }
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68 |
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69 | // Updates the frustum planes. Should be called
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70 | // everytime the view or projection matrices are
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71 | // altered.
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72 | void UpdateFrustum(const CBoundingBoxAligned& scissor = CBoundingBoxAligned(CVector3D(-1.0f, -1.0f, -1.0f), CVector3D(1.0f, 1.0f, 1.0f)));
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73 | void ClipFrustum(const CPlane& clipPlane);
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74 | const CFrustum& GetFrustum() const { return m_ViewFrustum; }
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75 |
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76 | void SetViewPort(const SViewPort& viewport);
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77 | const SViewPort& GetViewPort() const { return m_ViewPort; }
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78 | float GetAspectRatio() const;
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79 |
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80 | float GetNearPlane() const { return m_NearPlane; }
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81 | float GetFarPlane() const { return m_FarPlane; }
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82 | float GetFOV() const { return m_FOV; }
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83 | float GetOrthoScale() const { return m_OrthoScale; }
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84 |
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85 | // Returns a quad of view in camera space at given distance from camera.
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86 | void GetViewQuad(float dist, Quad& quad) const;
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87 |
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88 | // Builds a ray passing through the screen coordinate (px, py), calculates
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89 | // origin and direction of the ray.
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90 | void BuildCameraRay(int px, int py, CVector3D& origin, CVector3D& dir) const;
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91 |
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92 | // General helpers that seem to fit here
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93 |
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94 | // Get the screen-space coordinates corresponding to a given world-space position
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95 | void GetScreenCoordinates(const CVector3D& world, float& x, float& y) const;
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96 |
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97 | // Get the point on the terrain corresponding to pixel (px,py) (or the mouse coordinates)
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98 | // The aboveWater parameter determines whether we want to stop at the water plane or also get underwater points
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99 | CVector3D GetWorldCoordinates(int px, int py, bool aboveWater=false) const;
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100 | // Get the point on the plane at height h corresponding to pixel (px,py)
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101 | CVector3D GetWorldCoordinates(int px, int py, float h) const;
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102 | // Get the point on the terrain (or water plane) the camera is pointing towards
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103 | CVector3D GetFocus() const;
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104 |
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105 | // Build an orientation matrix from camera position, camera focus point, and up-vector
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106 | void LookAt(const CVector3D& camera, const CVector3D& focus, const CVector3D& up);
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107 |
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108 | // Build an orientation matrix from camera position, camera orientation, and up-vector
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109 | void LookAlong(const CVector3D& camera, CVector3D orientation, CVector3D up);
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110 |
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111 | /**
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112 | * Render: Renders the camera's frustum in world space.
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113 | * The caller should set the color using glColorXy before calling Render.
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114 | *
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115 | * @param intermediates determines how many intermediate distance planes should
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116 | * be hinted at between the near and far planes
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117 | */
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118 | void Render(int intermediates = 0) const;
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119 |
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120 | public:
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121 | // This is the orientation matrix. The inverse of this
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122 | // is the view matrix
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123 | CMatrix3D m_Orientation;
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124 |
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125 | private:
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126 | CMatrix3D m_ProjMat;
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127 | ProjectionType m_ProjType = ProjectionType::CUSTOM;
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128 |
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129 | float m_NearPlane = 0.0f;
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130 | float m_FarPlane = 0.0f;
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131 | union
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132 | {
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133 | float m_FOV;
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134 | float m_OrthoScale;
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135 | };
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136 | SViewPort m_ViewPort;
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137 |
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138 | CFrustum m_ViewFrustum;
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139 | };
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140 |
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141 | #endif // INCLUDED_CAMERA
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