[Solved]Scaling

[Dr.Tyler O.]

First of all, I apologize if there are already topics that answer this question. I have looked but I didn't see anything that I thought could help provide a solution to my problem. Anyway, the issue is that, when using love.graphics.scale(), I want to be able to scale the graphics without changing the position at which I view them. If you download the attached .love file you will understand what I mean. I only wish for the ball to appear as though it is getting bigger/smaller without changing the perspective at which it is seen. And, just a side note, I'm not looking for any sort of code edit that changes the scale of the actual image.

[micha]

The scaling is always applied with respect to the origin, which is in the upper left corner. If you want to scale from the center, then you can perform these three transformations in a row:
1) Translate (Move the screen center to the top left)
2) Scale
3) Translate (Move the top left back to the center)

Mathematically, these three transformations can be reduced to two.
1) Scale
2) Translate (correct for the offset)

To get the specific number for this second step you have to rearrange some terms. Translation means something is added to the coordinates. Scaling means they are multiplied. So the operations of the 3-transformation-solution are:

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x_out = ((x_in - tx) * s ) + tx
y_out = ((y_in - ty) * s ) + ty

(s is the scaling factor and (tx,ty) is the translation vector pointing from the origin to the center)
After the rearrangement you get

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x_out = x_in * s + (1-s) * tx
y_out = y_in * s  + (1-s) * ty

This is a scaling by factor s and a translation by (1-s)*(tx,ty)