lib/gamnit/camera_control_linux.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 # Mouse wheel and middle mouse button to control camera
  16 module camera_control_linux
  17
  18 import linux
  19 import camera_control
  20
  21 redef class EulerCamera
  22
  23         # Zoom factor, default at 1.2, higher means more reactive zoom effect
  24         var camera_zoom_mod = 1.2 is writable
  25
  26         # Scroll trigger button mask from SDL2 (1: left, 2: middle, 4: right)
  27         #
  28         # Set to 0 to deactivate the scrolling feature.
  29         var camera_pan_mask = 2 is writable
  30
  31         redef fun accept_scroll_and_zoom(event)
  32         do
  33                 # Zoom
  34                 if event isa GamnitMouseWheelEvent then
  35                         var dy = event.y
  36                         var mod = camera_zoom_mod
  37                         if dy > 0.0 then
  38                                 # Zoom in when moving the wheel up
  39                                 mod = 1.0/mod
  40                         else dy = -dy
  41
  42                         position.z *= dy * mod
  43                         return true
  44                 end
  45
  46                 # Scroll
  47                 var but_mask = camera_pan_mask
  48                 if but_mask != 0 and event isa GamnitPointerEvent then
  49                         var native = event.native
  50                         if native isa SDLMouseMotionEvent and native.state & but_mask == but_mask then
  51                                 var dx = native.xrel.to_f
  52                                 var dy = native.yrel.to_f
  53
  54                                 var world_height = field_of_view_y.sin * position.z
  55                                 var mod = app.display.as(not null).height.to_f / world_height
  56                                 position.x -= dx / mod
  57                                 position.y += dy / mod # Y is inverted between the input and output
  58                                 return true
  59                         end
  60                 end
  61
  62                 return false
  63         end
  64 end