Lemma Soft Forums

orz wrote:Why not make the image a composite (using LiveComposite) and just moving that around?

AlphaMask(LiveComposite( (1920,1080), (0,0), "sprite.png") , "mask.png")

Onishion wrote:I'd like to know an easy way to do this as well, but there might be a cheap workaround to it, if this would work for your project.

1. Take the background you're using.

2. Duplicate that background, and display the second copy of it on a layer above the object you want to move around.

3. Alpha that second "background" to have holes wherever you want to see your object, and be opaque where you want the object invisible.

That way, it should provide the effect you're describing.

That's an interesting workaround. However, in my case, there's a number of different backgrounds and animated sprites all preexisting behind this masked animated element, so it's not as simple as duplicating and masking a single background...

image sprite:
    "sprite.png"
    #Animation data here

image maskedsprite:
    AlphaMask("sprite", "mask.png")

Onishion wrote:

1. Take the background, and make a composite image that is the background AND all images that you want to be behind the moving object.

2. Duplicate that image, use it as the foreground with the alpha thing going on, with the moving object sandwiched between.

Which works as expected. However, whilst transforms such as zoom and rotate can be applied and even animated with linear in that preliminary image definition, positional transforms (namely, pos and offset) used in exactly same way have no effect. I'm not entirely sure as to why this is - perhaps someone with a deeper understanding of the AlphaMask function could offer an explanation for this behaviour?

I can imagine that working; the only problem is that this masked animation occurs quite regularly at various points, with no particular way of knowing what else may or may not be present behind it on the screen in any given instance...

nyaatrap wrote:It looks you want to mask a layer, not an image. It can be done when you show an image on a higher layer then apply an alpha transition on the layer.

init python:
    config.layers = ["master", "transient", "screens", "overlay", "sprites"]

define spriteMask = AlphaDissolve("mask.png", delay=1.1, alpha=True)

image sprite:
    #blah blah animation goes here

label start:
    show layer sprites at spriteMask
    show sprite onlayer sprites

TypeError: __init__() got multiple values for keyword argument 'delay'

TARDISam24 wrote:

nyaatrap wrote:It looks you want to mask a layer, not an image. It can be done when you show an image on a higher layer then apply an alpha transition on the layer.

That sounds like it could work!

I've gotten this so far:

Code: Select all

init python:
    config.layers = ["master", "transient", "screens", "overlay", "sprites"]

define spriteMask = AlphaDissolve("mask.png", delay=1.1, alpha=True)

image sprite:
    #blah blah animation goes here

label start:
    show layer sprites at spriteMask
    show sprite onlayer sprites

The actual masking effect works correctly in tandem with the animations when tested separately. However, upon the show statements, I get the following critical error:

Code: Select all

TypeError: __init__() got multiple values for keyword argument 'delay'

The fact the masking transformation is actually a transition strikes me as odd; I've just thrown in a suitable value of 1.1 for 'delay'. But, it doesn't seem to like this.

PyTom wrote:So, the problem is that you're trying to use AlphaDissolve, but it's a Transition, not a Transform - and so won't work. I think want you probably want is an AlphaMask transform. That doesn't exist in the form you want, but we can easily create one.

Code: Select all

init python:
     def SpriteMask(d):
         return AlphaMask(d, "mask.png")

show layer sprites at SpriteMask