Collision detection and opacity

[Webmaster4o]

I need to know how to use collision detection and how to give an object opacity. Could someone please post some code???
Thx
—Webmaster4o

[ccc]

Look at the gists in this thread for code that does collision detection:<br />
http://omz-forums.appspot.com/pythonista/post/4695137988902912

---

Changing a scene.Layer.alpha value will change that Layer's transparency / opacity.<br />
alpha = 0.0 means the Layer is fully transparent<br />
alpha = 1.0 means the Layer is fully opaque

import scene

class MyScene(scene.Scene):
    def __init__(self):
        scene.run(self)

    def setup(self):
        center = self.bounds.center()
        self.layer = scene.Layer(scene.Rect(center.x - 64, center.y - 64, 128, 128))
        self.layer.alpha = 0  # 0.0 = fully transparent, 1.0 = fully opaque
        self.layer.background = scene.Color(1, 0, 0)
        self.layer.image = 'Snake'
        self.add_layer(self.layer)

    def draw(self):
        scene.background(0, 0, 0)
        self.root_layer.update(self.dt)
        self.root_layer.draw()
        self.layer.alpha += .01  # cycle the layer's alpha value
        if self.layer.alpha > 1:
            self.layer.alpha = 0

MyScene()

scene.Color objects also have an alpha value that you can mess with: scene.Color(red, green, blue, alpha)

[Gerzer]

If you want collision detection for Rect objects, use the Rect.intersects(other_rect) method. It returns a bool value. An example:

from scene import *
class MyScene(Scene):
   def draw(self):
        fill(1, 0, 0)
        rect(0, 0, 50, 75)
        r1 = Rect(0, 0, 50, 75)
        rect(0, 0, 50, 25)
        r2 = Rect(0, 0, 50, 25)
        if r1.intersects(r2):
            print "R1 intersects R2"
run(MyScene()) # Please note that this script will continuously produce output in the console, so stop the script quickly.

This only works for Rect objects.
I hope that helps!

[Sebastian]

This works with circles:

from scene import *

def centered_ellipse(x, y, w, h):
	ellipse(x-w/2, y-h/2, w, h)

class MyScene (Scene):
	def setup(self):
		self.pos = Point(self.size.w/2, self.size.h/2)
		self.pos2 = Point(0, 0)
		
	def draw(self):
		background(0, 0, 0)
		centered_ellipse(self.pos.x, self.pos.y, 100, 100)
		centered_ellipse(self.pos2.x, self.pos2.y, 100, 100)
		for touch in self.touches.values():
			self.pos2 = touch.location
			if self.pos.distance(self.pos2) < 100:
				fill(1, 0, 0)
			else: 
				fill(1, 1, 1)
				
run(MyScene())