lib/matrix/projection.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #     http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15 # Services on `Matrix` to transform and project 3D coordinates
  16 module projection
  17
  18 intrude import matrix
  19
  20 redef class Matrix
  21
  22         # Create an orthogonal projection matrix
  23         #
  24         # `left, right, bottom, top, near, far` defines the world clip planes.
  25         new orthogonal(left, right, bottom, top, near, far: Float)
  26         do
  27                 var dx = right - left
  28                 var dy = top - bottom
  29                 var dz = far - near
  30
  31                 assert dx != 0.0 and dy != 0.0 and dz != 0.0
  32
  33                 var mat = new Matrix.identity(4)
  34                 mat[0, 0] = 2.0 / dx
  35                 mat[3, 0] = -(right + left) / dx
  36                 mat[1, 1] = 2.0 / dy
  37                 mat[3, 1] = -(top + bottom) / dy
  38                 mat[2, 2] = 2.0 / dz
  39                 mat[3, 2] = -(near + far) / dz
  40                 return mat
  41         end
  42
  43         # Create a perspective transformation matrix
  44         #
  45         # Using the given vertical `field_of_view_y` in radians, the `aspect_ratio`
  46         # and the `near`/`far` world distances.
  47         new perspective(field_of_view_y, aspect_ratio, near, far: Float)
  48         do
  49                 var frustum_height = (field_of_view_y/2.0).tan * near
  50                 var frustum_width = frustum_height * aspect_ratio
  51
  52                 return new Matrix.frustum(-frustum_width, frustum_width,
  53                                           -frustum_height, frustum_height,
  54                                           near, far)
  55         end
  56
  57         # Create a frustum transformation matrix
  58         #
  59         # `left, right, bottom, top, near, far` defines the world clip planes.
  60         new frustum(left, right, bottom, top, near, far: Float)
  61         do
  62                 var dx = right - left
  63                 var dy = top - bottom
  64                 var dz = far - near
  65
  66                 assert near > 0.0
  67                 assert far > 0.0
  68                 assert dx > 0.0
  69                 assert dy > 0.0
  70                 assert dz > 0.0
  71
  72                 var mat = new Matrix(4, 4)
  73
  74                 mat[0, 0] = 2.0 * near / dx
  75                 mat[0, 1] = 0.0
  76                 mat[0, 2] = 0.0
  77                 mat[0, 3] = 0.0
  78
  79                 mat[1, 0] = 0.0
  80                 mat[1, 1] = 2.0 * near / dy
  81                 mat[1, 2] = 0.0
  82                 mat[1, 3] = 0.0
  83
  84                 mat[2, 0] = (right + left) / dx
  85                 mat[2, 1] = (top + bottom) / dy
  86                 mat[2, 2] = -(near + far) / dz
  87                 mat[2, 3] = -1.0
  88
  89                 mat[3, 0] = 0.0
  90                 mat[3, 1] = 0.0
  91                 mat[3, 2] = -2.0 * near * far / dz
  92                 mat[3, 3] = 0.0
  93
  94                 return mat
  95         end
  96
  97         # Apply a translation by `x, y, z` to this matrix
  98         fun translate(x, y, z: Float)
  99         do
 100                 for i in [0..3] do
 101                         self[3, i] = self[3,i] + self[0, i] * x + self[1, i] * y + self[2, i] * z
 102                 end
 103         end
 104
 105         # Apply scaling on `x, y, z` to this matrix
 106         fun scale(x, y, z: Float)
 107         do
 108                 for i in [0..3] do
 109                         self[0, i] = self[0, i] * x
 110                         self[1, i] = self[1, i] * y
 111                         self[2, i] = self[2, i] * z
 112                 end
 113         end
 114
 115         # Create a rotation matrix by `angle` around the vector defined by `x, y, z`
 116         new rotation(angle, x, y, z: Float)
 117         do
 118                 var mat = new Matrix.identity(4)
 119
 120                 var mag = (x*x + y*y + z*z).sqrt
 121                 var sin = angle.sin
 122                 var cos = angle.cos
 123
 124                 if mag > 0.0 then
 125                         x = x / mag
 126                         y = y / mag
 127                         z = z / mag
 128
 129                         var inv_cos = 1.0 - cos
 130
 131                         mat[0, 0] = inv_cos*x*x + cos
 132                         mat[0, 1] = inv_cos*x*y - z*sin
 133                         mat[0, 2] = inv_cos*z*x + y*sin
 134
 135                         mat[1, 0] = inv_cos*x*y + z*sin
 136                         mat[1, 1] = inv_cos*y*y + cos
 137                         mat[1, 2] = inv_cos*y*z - x*sin
 138
 139                         mat[2, 0] = inv_cos*z*x - y*sin
 140                         mat[2, 1] = inv_cos*y*z + x*sin
 141                         mat[2, 2] = inv_cos*z*z + cos
 142                 end
 143                 return mat
 144         end
 145
 146         # Apply a rotation of `angle` radians around the vector `x, y, z`
 147         fun rotate(angle, x, y, z: Float)
 148         do
 149                 var rotation = new Matrix.rotation(angle, x, y, z)
 150                 var rotated = self * rotation
 151                 self.items = rotated.items
 152         end
 153 end