lib/gamnit: intro `EulerCamera::reset_to_fit`

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/gamnit/cameras.nit b/lib/gamnit/cameras.nit
index 43aae77..2dfc706 100644 (file)
--- a/lib/gamnit/cameras.nit
+++ b/lib/gamnit/cameras.nit
@@ -38,7 +38,7 @@ abstract class Camera
        fun mvp_matrix: Matrix is abstract
 end
 
-# Simple camera with perspective oriented with Euler angles (`pitch`, `yaw`, `roll`)
+# Simple camera with perspective oriented with Euler angles (`pitch, yaw, roll`)
 class EulerCamera
        super Camera
 
@@ -63,8 +63,8 @@ class EulerCamera
 
        # Clipping wall the farthest of the camera, in world dimensions
        #
-       # Default at `100.0` but this one should be adapted to each context.
-       var far = 100.0 is writable
+       # Default at `10000.0` but this one should be adapted to each context.
+       var far = 10000.0 is writable
 
        # Look around sensitivity, used by `turn`
        var sensitivity = 0.005 is writable
@@ -127,6 +127,30 @@ class EulerCamera
 
                return view * projection
        end
+
+       # Reset the camera position so that `height` world units are visible on the y axis at z=0
+       #
+       # By default, `height` is set to `display.height`.
+       #
+       # After the reset, the camera sits on the Z axis and rotation values are reset to 0.
+       # The X axis is horizontal on the screen and the Y axis is vertical.
+       # Higher values on the Z axis are closer to the camera.
+       fun reset_height(height: nullable Float)
+       do
+               if height == null then height = display.height.to_f
+
+               var opp = height / 2.0
+               var angle = field_of_view_y / 2.0
+               var adj = opp / angle.tan
+
+               position.x = 0.0
+               position.y = 0.0
+               position.z = adj
+
+               pitch = 0.0
+               yaw = 0.0
+               roll = 0.0
+       end
 end
 
 # Orthogonal camera to draw UI objects with services to work with screens of different sizes