Single Pointer LUT problem....

[relsoft]

Hi I am having problems with lookup tables in my game. Basically , I would want to use precalculated values instead of calculating it on the fly.

This would be tbe init code:

Code:

dim pm_sin as single ptr
dim pm_cos as single ptr
pm_sin = callocate(len(single) * 360)
pm_cos = callocate(len(single) * 360)
for i = 0 to 359
    pm_sin[i] = sin(i * 3.141593 / 180)
    pm_cos[i] = cos(i * 3.141593 / 180)
next i

Why would this fail:

Code:

dim angle as integer
angle = ( m_angle + i * (STEPSEGMENT - 2) )
if angle > 359 then angle = angle - 360
.ps_followers[i].m_x = MainEnemy.m_x + 24 + (pm_cos[ angle ] * 70)
.ps_followers[i].m_y = MainEnemy.m_y + 28 + (pm_sin[ angle ] * 60)

And this not:

Code:

dim angle as single
angle = ( m_angle + i * (STEPSEGMENT - 2) ) * 3.141593 /180
if angle > 359 then angle = angle - 360
.ps_followers[i].m_x = MainEnemy.m_x + 24 + cos(angle) * 70
.ps_followers[i].m_y = MainEnemy.m_y + 28 + sin(angle) * 60

Actually, it does not give me an error, but the effect of the two codes is a lot different. With Luts, some of the sprites "jump" off the desired position. :*(

Thanks in advance!

[Mitthrawnuruodo]

this is just a guess, but what happends when you make the pm_sin + pm_cos double ptrs?

I looked and the only difference between the two that I saw was that the sin() + cos() were giving a double and the pm_sin[] and the pm_cos[] were giving a single.....try it, see what happends.

EDIT:
It could also be that your losing data when you dim the angle as an integer in the first one. Try dimming that as a single as well :wink: .

[Antoni Gual]

Make angle a single and use cint(angle) as the index to the LUT. With angle as integer the increases below 0.5 do not build up as they are rounded...

[relsoft]

Lillo help me. Stupid mistake actually:

Code:

while angle > 359 : angle = angle - 360: wend

Thanks anyways. :*)