i had game maker 7 pro, but for some reason my computer isn't letting me use it anymore which means i can't finish this project anymore because i need pro to finish, but the funny thing is that it would load game maker 7 lite instead, and when i try getting pro it just does it all ver again.

any help?

Is it showing you what word is causing the problem?

Keeping things as variables also makes it a lot easier to change said magic numbers when you need to, then you only have to change the variable rather than go through the code and change each instance of the number.

Magic numbers are numbers used in your code. All numbers in your code should always be defined as constants, both for re-usability and readability.

I know this… but I can't seem to follow the practice. :)

—hartnell

NEVER use 'magic numbers' in your source such as the statement […] you may remember as you are working on the project, but what about in a year's time when you come back to re-use some of this source?

P.s. Magic numbers are numbers used in your code. All numbers in your code should always be defined as constants, both for re-usability and readability.

They discussed Collision Detection in part 6 using the 'Bit-Mask method', mentioned by u9.

I've taken all 7 parts of the tutorial and uploaded them here. (5.72 MB)

Basically you first make a bit-mask of the two sprites, so that each bit represents 1 pixel. Then when the two bounding boxes intersect (a quick test) i guess you calculate the common area of the two colliding bit-masks and using the shift operator for aligning the two bit-masks you can test the area of intersection very quickly. It's maybe a little complicated.

Here's a little quote:

The idea is to identify the common area of the two masks, and then perform a bitwise AND to check if they share a common ’1’- bits. This way we can check 32 bits at a time which speeds up the test enormously

Personally i would rather creating a polygon around each of my objects and then test if these collide mathematically. Doing so allows me to rotate my sprites easily without it effection collision detection.

I have a great book about real time collision detection, so if you want to try this, let me know :)

Engineer pixel perfect collision without the use of any special game programming functions or libraries.

—hartnell