Smooth linear filtering on moving objects

[Sam_The_Man]

Hi guys

I noticed that despite this version of MMF using hardware acceleration, that it doesn't allow you to position an object at decimal point positions and therefore it isn't able to make an active move smoothly from one pixel to another.

However, I found a really simple way to get around this limitation by using a pixel shader! And its really easy to impliment!

All you have to do is go to http://complex.ovh.org/index.php?p=extensions&c=8#prod8 and download the shaders pack. Once installed, select your object that you want to have the smooth linear filtering and give it the 'zoom and offset' pixel shader.

Now, because MMF doesn't allow you to move an object around in decimal points, you have to use alterable values. Start off by initialising the alterable values like so:

Start of frame
- Set Value A to X("Active")
- Set Value B to Y("Active")

Then simply add in your events to move your object around, but rather than affecting the X and Y values (because they are limited to integer values), modify Value A and B
Key left is down
- Add -0.1 to Value A
... etc

Then the event:
Always
Set X to Value A
Set Y to Value B

Now, mmf will round X and Y to the lowest integer, so we caculate the offset like this:
0-(Alterable Value A( "Active" )-X( "Active" ))/(X Right( "Active" )-X Left( "Active" )+0.0)
...because the offset value isn't in pixels, its in a range between 0 and 1, 1 being the total width of the object, so we need to divide it by the width of the active. As there is no expression to get the width of an object, we use Right - Left.

I have attached a mfa file demonstrating the effect. The shape at the top moves around with the linear filtering, while the shape below doesn't.

[SEELE]

It would be great if this was built in to mmf (as in float point positions)

[Nifflas]

I agree! It's probably a big thing to change though (changing a data type from integer to float for all position things related to MMF2, and getting everything to work with that instead), but let's hope it will work in MMF3.

[MechatheSlag]

Already been mentioned and acknowledged several times. The reason I don't use it is because it is hardly noticable in most games, unless you have a mouse cursor or something.

[Werbad]

One reason would be that the pixel precise collision detection mmf uses won't really work if the object can be placed at sub-pixel positions.

[Nifflas]

The collision mask could be placed on the nearest integer position, and the sub-pixel stuff could be used for displaying things only.

[LazyCoder]

I had already created one of these a long time ago. I kept trying to add more cool stuff to it too, like directional blur and stuff like that. I gave up pretty quickly...

[uprize]

i think this is pretty cool!

[Sebaceous]

I'm using arrays to get around this, having my run movement go (+1, +2, +1, +1, +2, +1, +2, +2, +1, +2) for example.

[LazyCoder]

...what?