Fastest vertex rotation method?

Blitz3D Forums/Blitz3D Programming/Fastest vertex rotation method?

Gabriel

(Posted 2003) [#1]

You may have noticed from some of my previous questions that 3d maths isn't really my thing, and I do usually try to write games that don't require a ton of it ( honest ) but it's unavoidable sometimes.

I'm about to start work on it now, and I figure I'm going to create a pivot, rotate it and use TFormPoint and TFormNormal to rotate the vertices and their normals. At least that's what I hope I'm going to do.

But before I strain my brain getting the coordinates the right way around and trying to remember which is pitch and which is yaw.. is this the fastest way?

If it isn't, what's the fastest way of rotating vertices?

Rottbott

(Posted 2003) [#2]

I don't quite understand how you can rotate a point..

HNPhan

(Posted 2003) [#3]

i think he meant to rotate vertices along a rotation center.

Wayne

(Posted 2003) [#4]

RotateEntity entity,pitch#,yaw#,roll#,[,global]

Parameters:

entity - name of the entity to be rotated
pitch# - angle in degrees of pitch rotation
yaw# - angle in degrees of yaw rotation
roll# - angle in degrees of roll rotation
global (optional) - true if the angle rotated should be relative to 0,0,0 rather than a parent entity's orientation. False by default.

HNPhan

(Posted 2003) [#5]

.. thats not quite it i think, that would be for an entity, hes talking about an individual vertex

Sveinung

(Posted 2003) [#6]

Maybi this it will work


for i=1 to nrpoint

;or what ever :)
x#=x_ponit(i)
y#=y_ponit(i)
z#=z_ponit(i)

; rotate x-axis
x1#=x#
y1#=(cos(ang)*y#)+(sin(ang)*z#)
z1#=(sin(ang)*z#)-(cos(ang)*y#)

;roate y-axis
x2#=(cos(ang)*x1#)+(sin(ang)*z1#)
y2#=y1#
z2#=(sin(ang)*z1#)-(cos(ang)*x1#)

;rotate z-axis
x1#=(cos(ang)*x2#)+(sin(ang)*y2#)
y1#=(cos(ang)*y2#)+(sin(ang)*x2#)
z1#=z2#

x_ponit(i)=x1#
y_ponit(i)=y1#
z_ponit(i)=z1#

next

Note the most optimized code...but I think you get
the general idea :)

Sveinung

Sveinung

(Posted 2003) [#7]

Well...my spelling sux!!!

Hehe damn I sux

Sorry

Sveinung

DareDevil

(Posted 2003) [#8]

for fast calculate, precalculate table Sin Cos 4096 elements

and optimize the code this:

;precalculate Sin - Cos
cx# = cos(angx) : sx# = sin(angx)
cy# = cos(angy) : sy# = sin(angy)
cz# = cos(angz) : sz# = sin(angz)

for i=1 to nrpoint

;or what ever :)
x# = x_ponit(i)
y# = y_ponit(i)
z# = z_ponit(i)

; rotate x-axis
x1#=x#
y1#=(cx#*y#)+(sx#*z#)
z1#=(sx#*z#)-(cx#*y#)

;rotate y-axis
x2#=(cy#*x1#)+(sy#*z1#)
y2#=y1#
z2#=(sy#*z1#)-(cy#*x1#)

;rotate z-axis
x1#=(cz#*x2#)+(sz#*y2#)
y1#=(cz#*y2#)+(sz#*x2#)
z1#=z2#

x_ponit(i)=x1#
y_ponit(i)=y1#
z_ponit(i)=z1#

next

for very speed use value interger, moltiplicate all value point and sin cos for 10000 and after moltiplicate 0.0001

Bye

Anthony Flack

(Posted 2003) [#9]

Someone recently posted (I can't remember who) saying they'd been using a "dummy" quad; rotating that using the native entity commands, and then copying out the vertex co-ords to the target vertices. Something like that, anyway. The intersting thing was that he reckoned it was actually quite a bit faster than using the vertex rotation commands in the code archives.

I can't confirm any of this though, it's just what I read. I expect my own rotation commands could do with some optimising too...