Raycasting help

[killjoy1337]

I am trying to design a basic raycasting engine in turing, I am using the tutorial at http://www.permadi.com/tutorial/raycast/


My problem is that when I try to do the equation:

A.x = Px + (Py-A.y)/tan(ALPHA)

When I get the tangent of the angle of the ray it varies greatly and is obviously not the right answer, sometimes it gets into the thousands. I am not sure what the problem is, if it is turing (with it's x,y plane being down-up incresing instead of the other way around) or my math itself, any help would be appreciated

Note: I have tried tand(ALPHA) and tan(ALPHA) in turing

[SNIPERDUDE]

tan is messed up in Turing, make your own function that returns sin(a) / cos(a)
Hope that helps!

[The_Bean]

The tan function works perfectly fine for me in Turing.

Getting results in the thousands is reasonable

code:

tand(89.)=           57.289962 tand(89.9)=          572.957213 tand(89.99)=         5729.577893 tand(89.999)=        57295.779508 tand(89.9999)=       572957.795157 tand(89.99999)=      5.729578e6 tand(89.999999)=     5.729578e7 tand(89.9999999)=    5.729578e8 tand(89.99999999)=   5.729577e9 tand(89.999999999)=  5.729439e10 tand(89.9999999999)= 5.729368e11

Which is visible by the graph of tan and better explained here http://www.wolframalpha.com/input/?i=lim+n-%3E+(pi/2)+tan(n)

[CodeMonkey2000]

Are you sure your ALPHA is correct?

EDIT: Try drawing the grid and the basic ray to see what's going on. And if you are using arc tan to compute alpha, you could just not take the arc tan altogether and remember the ratio instead of the angle.

[killjoy1337]

Here is my code so far, I just have it printing the value of x_step which is 64/tan(a), at some values it looks correct but then it shoots way up into the thousands around 360/0 and 180 and 90 and 270, any help would be appreciated. Also if there is a better way of doing raycasting in turing please let me know, thanks for the suggestions so fars

[DemonWasp]

Well, tan ( 90 ) = 0, tan ( 180 ) = 0, ... you do remember what happens when you divide by zero, right?

[CodeMonkey2000]

From the looks of your cast ray procedure, I don't know if you are doing it correctly. Like I said before, draw the ray to make sure. And you missed the step of getting a.x and a.y. Just by looking at the numbers, it is basically impossible to tell if you are right or wrong. And for angles 360,90,270 and 180, like DemonWasp pointed out, these are special cases. You have to understand how raycasting works to resolve them properly.

Also search for other raycasting engines, like mine or asiansensation's. The one I did ages had 4 versions, a 2d version to make sure my rays were correct, a non textured version, a textured version and a high resolution version.