I am trying to make a simple arcade shooter like Galaga in TIBasic. I have successfully created some code that lets you move your character (an "X") horizontally across the screen while shooting a bullet that clears everything along the vertical path it takes. However, I'm having a problem with the "rocks" that are supposed to fall from the screen and disappear when hit. When I shoot the rock, it is cleared by the bullet, but then continues going down the screen until it hits the bottom of the screen. Here's the code for the rocks:
//outside the game loop:
1->R
//inside game loop:
If not(R=8)
Then
R+1->R
If R>1
Then
Output(E-1, 1, " " //removes last rock
End
Output(R, 1, "R" //replaces last rock with one below it (traveling towards the ground)
End
This code obviously doesn't stop the "R" from continuing to go down the screen when it is cleared (by the way, I just use Output(...," ") on wherever the bullet was to clear away anything the bullet hits). So, how would I check if the rock was cleared away on the last iteration of the game loop? Is there a way to check if something (the "R") is at a certain place on the screen in order to check if it was cleared away by a bullet on the last iteration? Or is there a better way? Thanks for the help!
It appears that the code you have doesn't test if the bullet is in the same place as the rock. To have this collision, you'd need to compare the "R" y-value of the rock with the y-value of your bullet you displayed, and compare the x-value of the rock (however you store that) with the x-value of the bullet. If both are equal to each other, then they have collided, and you can "delete" the rock by setting it to whatever value signifies it doesn't exist anymore. Assuming R is the y-value of the rock, S is the x-value of the rock, Y is the y-value of the bullet, and X is the x-value of the bullet, In the code to move the rock, I'd put this somewhere:
:If R=Y and S=X
:DelVar R
//You could also delete the bullet here because it's "stopped" by the rock
This code will test if the two are collided and set R to 0 (meaning it doesn't exist). If you wanted, you could also add a text-version of an explosion to give it some more flair. Good luck with your project, and I hoped this helped!