From: Alexis Laferrière <alexis.laf@xymus.net>
Date: Wed, 5 Apr 2017 19:10:22 +0000 (-0400)
Subject: gamnit: implement `camera_control` for linux
X-Git-Url: http://nitlanguage.org

gamnit: implement `camera_control` for linux

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

diff --git a/lib/gamnit/camera_control_linux.nit b/lib/gamnit/camera_control_linux.nit
new file mode 100644
index 0000000..8c92e91
--- /dev/null
+++ b/lib/gamnit/camera_control_linux.nit
@@ -0,0 +1,64 @@
+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Mouse wheel and middle mouse button to control camera
+module camera_control_linux
+
+import linux
+import camera_control
+
+redef class EulerCamera
+
+	# Zoom factor, default at 1.2, higher means more reactive zoom effect
+	var camera_zoom_mod = 1.2 is writable
+
+	# Scoll trigger button mask from SDL2 (1: left, 2: middle, 4: right)
+	#
+	# Set to 0 to deactivate the scrolling feature.
+	var camera_pan_mask = 2 is writable
+
+	redef fun accept_scroll_and_zoom(event)
+	do
+		# Zoom
+		if event isa GamnitMouseWheelEvent then
+			var dy = event.y
+			var mod = camera_zoom_mod
+			if dy > 0.0 then
+				# Zoom in when moving the wheel up
+				mod = 1.0/mod
+			else dy = -dy
+
+			position.z *= dy * mod
+			return true
+		end
+
+		# Scroll
+		var but_mask = camera_pan_mask
+		if but_mask != 0 and event isa GamnitPointerEvent then
+			var native = event.native
+			if native isa SDLMouseMotionEvent and native.state & but_mask == but_mask then
+				var dx = native.xrel.to_f
+				var dy = native.yrel.to_f
+
+				var world_height = field_of_view_y.sin * position.z
+				var mod = app.display.as(not null).height.to_f / world_height
+				position.x -= dx / mod
+				position.y += dy / mod # Y is inverted between the input and output
+				return true
+			end
+		end
+
+		return false
+	end
+end