Dynamic sprite difficulty

[FortressCaulfield]

Trying to use dynamic sprites to create a space window with stars and such whizzing by and none of it is working. I copied the code from the 2nd reply here:

https://www.adventuregamestudio.co.uk/forums/beginners-technical-questions/round-gui-for-a-minimap/msg636663807/

Code: ags

DynamicSprite* space;
int spacex = 0;

void repeatedly_execute_always()
{
  space = DynamicSprite.CreateFromExistingSprite(946);
  space.Crop(spacex, 0, Game.SpriteWidth[948] + spacex, Game.SpriteHeight[948]);
  space.CopyTransparencyMask(948);
  oSpace.Graphic = space.Graphic;
  spacex += 1;
}

946 is a long image of stars. 948 is the mask for the window.

When the room loads, it immediately crashes, complaining the transparency mask is not the same size. That's sprite 948. I tried putting in the height and width values directly, referincing them from 948's dimensions, modifying by -1, +1, nothing made it happy.

If I comment out that line, then the image loads but never updates even once. The repeatedly execute and spacex increment is working, it just never ever recrops the image.

EDIT: Turns out the redraw was working, but 1 pixel per cycle was too slow to notice. So that problem is solved. Still having the crop problem, and now a new one:

How do I make the image loop?

[Khris]

The Crop command's 3rd and 4th parameters are width and height, not x2 and y2.
I.e. you need to remove " + spacex" when you pass the width.

As for looping, replace "spacex += 1;" with:

Code: ags

  spacex = (spacex + 1) % (Game.SpriteWidth[946] - Game.SpriteWidth[948]);

The mod operator calculates the reminder, meaning it's the shorter way of doing:

Code: ags

  spacex++;
  if (spacex == SMALLEST_INVALID_VALUE) spacex = 0;

Btw: you can do this without cropping / copying the transparency mask: put the room background including holes for the windows in a sprite, then simply draw the stars followed by the room sprite to the room background's DrawingSurface.

[FortressCaulfield]

Thank you, that was driving me bananas.

> spacex = (spacex + 1) % (Game.SpriteWidth[946] - Game.SpriteWidth[948]);

This works also, thanks, just had to add a repeated section to the end of the graphic so that restarts are seamless. I'm familiar with mod but I rarely think to use it like this where you're making use of the return of the first operator if the 2nd one is bigger.