JVERSION
Engine: j803/2014-10-19-11:11:11
Library: 8.03.13
Qt IDE: 1.3.1/4.8.2
Platform: Linux 32
Installer: J803 install
InstallPath: /home/juhl/j803
api/gles version 1.0.21
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The current header of gl_Ortho:
gl_Ortho=: 3 : 0
looks like it should be:
gl_Ortho=: (gl_I'')&$: : (4 : 0)
The suggested change makes it match gl_Frustum
and allows it to be used both dyadically and monadically.
The original verb fails because it refers to x.
After much puzzling, I think glu_LookAt may be broken
- the following version matches my understanding
of how this verb should behave, based on the
gluLookAt function in OpenGL:
glu_LookAt=: 3 : 0
'eye center up'=. _3]\,>y
F=. center - eye
f=. (% +/&.:*:)F
UPP=. (% +/&.:*:)up
s=. f ((1&|.@:[ * _1&|.@:]) - _1&|.@:[ * 1&|.@:]) UPP
u=. s ((1&|.@:[ * _1&|.@:]) - _1&|.@:[ * 1&|.@:]) f
M=. |:_4]\ s, 0, u, 0, (-f), 0 0 0 0 1
M (+/ . *)~ gl_Translate -eye
)
In this revised version, eye and center are
points specified in world coordinates, and up
is a vector in world coordinates that will
be aligned to the positive y-axis in the viewing
coordinate system. My apologies if this is not
correct - I'm still trying to make sense of the
OpenGL ES viewing pipeline and J's binding to it.
The existing shader demo still works with this
version, and several small test scripts I've
written generate appropriate images as well.
Thanks,
Jim Uhl
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