source/camera.cpp

   1 #include <cmath>
   2 #include "camera.h"
   3 #include "matrix.h"
   4
   5 namespace Msp {
   6 namespace GL {
   7
   8 Camera::Camera():
   9         fov(Geometry::Angle<float>::from_turns(0.125)),
  10         aspect(4.0/3.0),
  11         clip_near(0.1),
  12         clip_far(10),
  13         frustum_x(0),
  14         frustum_y(0),
  15         position(0, 0, 0),
  16         look_dir(0, 0, -1),
  17         up_dir(0, 1, 0)
  18 { }
  19
  20 void Camera::set_field_of_view(const Geometry::Angle<float> &f)
  21 {
  22         fov = f;
  23 }
  24
  25 void Camera::set_aspect(float a)
  26 {
  27         aspect = a;
  28 }
  29
  30 void Camera::set_depth_clip(float n, float f)
  31 {
  32         clip_near = n;
  33         clip_far = f;
  34 }
  35
  36 void Camera::set_frustum_axis(float x, float y)
  37 {
  38         frustum_x = x;
  39         frustum_y = y;
  40 }
  41
  42 void Camera::set_position(const Vector3 &p)
  43 {
  44         position = p;
  45         compute_matrix();
  46 }
  47
  48 void Camera::set_up_direction(const Vector3 &u)
  49 {
  50         up_dir = normalize(u);
  51
  52         compute_matrix();
  53 }
  54
  55 void Camera::set_look_direction(const Vector3 &l)
  56 {
  57         look_dir = normalize(l);
  58
  59         compute_matrix();
  60 }
  61
  62 void Camera::look_at(const Vector3 &p)
  63 {
  64         set_look_direction(p-position);
  65 }
  66
  67 Vector3 Camera::project(const Vector4 &p) const
  68 {
  69         float frustum_h = tan(fov/2.0f);
  70         float frustum_w = frustum_h*aspect;
  71         float z_range = clip_far-clip_near;
  72
  73         Vector4 eye = matrix*p;
  74
  75         return Vector3(eye.x/frustum_w/-eye.z, eye.y/frustum_h/-eye.z,
  76                 (clip_far+clip_near)/z_range+2*clip_far*clip_near/(eye.z*z_range));
  77 }
  78
  79 Vector3 Camera::project(const Vector3 &p) const
  80 {
  81         return project(Vector4(p.x, p.y, p.z, 1.0));
  82 }
  83
  84 Vector4 Camera::unproject(const Vector4 &p) const
  85 {
  86         float frustum_h = tan(fov/2.0f);
  87         float frustum_w = frustum_h*aspect;
  88         float z_range = clip_far-clip_near;
  89
  90         float z = (2*clip_far*clip_near)/(p.z*z_range-(clip_far+clip_near))-matrix[14]*p.w;
  91         float x = p.x*-z*frustum_w-matrix[12]*p.w;
  92         float y = p.y*-z*frustum_h-matrix[13]*p.w;
  93
  94         return Vector4(matrix[0]*x+matrix[1]*y+matrix[2]*z,
  95                 matrix[4]*x+matrix[5]*y+matrix[6]*z,
  96                 matrix[8]*x+matrix[9]*y+matrix[10]*z,
  97                 p.w);
  98 }
  99
 100 void Camera::apply() const
 101 {
 102         float frustum_h = tan(fov/2.0f)*clip_near;
 103         float frustum_w = frustum_h*aspect;
 104         float left = frustum_w*(frustum_x-1.0f);
 105         float right = frustum_w*(frustum_x+1.0f);
 106         float bottom = frustum_h*(frustum_y-1.0f);
 107         float top = frustum_h*(frustum_y+1.0f);
 108         MatrixStack::projection() = Matrix::frustum(left, right, bottom, top, clip_near, clip_far);
 109         MatrixStack::modelview() = matrix;
 110 }
 111
 112 void Camera::compute_matrix()
 113 {
 114         Vector3 right_dir = normalize(cross(look_dir, up_dir));
 115         double mdata[16];
 116
 117         mdata[0] = right_dir.x;
 118         mdata[4] = right_dir.y;
 119         mdata[8] = right_dir.z;
 120
 121         mdata[1] = right_dir.y*look_dir.z-right_dir.z*look_dir.y;
 122         mdata[5] = right_dir.z*look_dir.x-right_dir.x*look_dir.z;
 123         mdata[9] = right_dir.x*look_dir.y-right_dir.y*look_dir.x;
 124
 125         mdata[2] = -look_dir.x;
 126         mdata[6] = -look_dir.y;
 127         mdata[10] = -look_dir.z;
 128
 129         mdata[12] = -position.x*mdata[0]-position.y*mdata[4]-position.z*mdata[8];
 130         mdata[13] = -position.x*mdata[1]-position.y*mdata[5]-position.z*mdata[9];
 131         mdata[14] = -position.x*mdata[2]-position.y*mdata[6]-position.z*mdata[10];
 132
 133         mdata[3] = 0;
 134         mdata[7] = 0;
 135         mdata[11] = 0;
 136         mdata[15] = 1;
 137
 138         matrix = mdata;
 139 }
 140
 141 } // namespace GL
 142 } // namespace Msp