lux@llumen.be

I'm lloking into the gl aspects of jitter at the moment,, since I understand that it renders a whole lot faster on GPU then on CPU

I was trying to get two shapes on top of each other (just planes out of jit.sketch) and stupid me kind of touht that when there is an rgba colormode the alpha would control overall transparency NOT

Is there a way to get a plane semi transparent and can someone please enlighten me on why th ere is a alpha in the color attribute?

I'm lloking into the gl aspects of jitter at the moment,, since  I understand that it renders a whole lot faster on GPU then on CPU

I was trying to get two shapes on top of each other (just planes out of jit.sketch) and stupid me kind of touht that when there is an rgba colormode the alpha would control overall transparency NOT
Is there a way to get a plane semi transparent and can someone please enlighten me on why th ere is a alpha in the color attribute?

gl-color-attribute-and-transparency

> I'm lloking into the gl aspects of jitter at the moment,, since I understand that it renders a whole lot faster on GPU then on CPU

> I was trying to get two shapes on top of each other (just planes out of jit.sketch) and stupid me kind of touht that when there is an rgba colormode the alpha would control overall transparency NOT

> Is there a way to get a plane semi transparent and can someone please enlighten me on why th ere is a alpha in the color attribute?

On 11/29/06, pieter coussement  wrote:
>
> Hi all,
>
> I'm lloking into the gl aspects of jitter at the moment,, since  I understand that it renders a whole lot faster on GPU then on CPU
>
> I was trying to get two shapes on top of each other (just planes out of jit.sketch) and stupid me kind of touht that when there is an rgba colormode the alpha would control overall transparency NOT
> Is there a way to get a plane semi transparent and can someone please enlighten me on why th ere is a alpha in the color attribute?
>
> Best regards
>
> pieter
>


ok that should have been obvious even to me

On 29 Nov 2006, at 18:39, Wesley Smith wrote:

>> I'm lloking into the gl aspects of jitter at the moment,, since I 

>> understand that it renders a whole lot faster on GPU then on CPU

>> I was trying to get two shapes on top of each other (just planes 

>> out of jit.sketch) and stupid me kind of touht that when there is 

>> an rgba colormode the alpha would control overall transparency NOT

>> Is there a way to get a plane semi transparent and can someone 

>> please enlighten me on why th ere is a alpha in the color attribute?

> Do you have @blend_enable 1 set?
>
> wes
>
> On 11/29/06, pieter coussement  wrote:
>>
>> Hi all,
>>
>> I'm lloking into the gl aspects of jitter at the moment,, since  I  
>> understand that it renders a whole lot faster on GPU then on CPU
>>
>> I was trying to get two shapes on top of each other (just planes  
>> out of jit.sketch) and stupid me kind of touht that when there is  
>> an rgba colormode the alpha would control overall transparency NOT
>> Is there a way to get a plane semi transparent and can someone  
>> please enlighten me on why th ere is a alpha in the color attribute?
>>
>> Best regards
>>
>> pieter
>>
>


Another stupid question I'm sure but looked into it and can't figure out what to do.

I have two movies one comes from a jit.qt and is rendered on a jit.gl.videoplane the other comes from a jit.matrix and I am using a submatrix to 'fly over the image' It's a picture of random vertical lines in some freaky fluo colours.

I want' to make that all that is black becomes transparent, I've read the forum, finding some examples with using alpha layers (which isn't an option I think) and am pretty shure I understand out of reading things about blendingmodes on the gl website it can be done to make everything that is black or has less luminance transparent (or in an advanced way more transparent)

It's just that I guess I am just to stupid to figure this out.

I have depth_enable turned off, because I read somewhere this shoud be off

ok the blending is what it is.
Another stupid question I'm sure but looked into it and can't figure out what to do.

Have you tried fiddling with the @blend_mode attribute? For instance,

I often use @blend_mode 6 1 for additive blending meaning things that

are black on top are transparent to non-black things below.

> Another stupid question I'm sure but looked into it and can't figure out what to do.

> I have two movies one comes from a jit.qt and is rendered on a jit.gl.videoplane the other comes from a jit.matrix and I am using a submatrix to 'fly over the image' It's a picture of random vertical lines in some freaky fluo colours.

> I want' to make that all that is black becomes transparent, I've read the forum, finding some examples with using alpha layers (which isn't an option I think) and am pretty shure I understand out of reading things about blendingmodes on the gl website it can be done to make everything that is black or has less luminance transparent (or in an advanced way more transparent)

> It's just that I guess I am just to stupid to figure this out.

> I have depth_enable turned off, because I read somewhere this shoud be off

Have you tried fiddling with the @blend_mode attribute?  For instance,
I often use @blend_mode 6 1 for additive blending meaning things that
are black on top are transparent to non-black things below.

On 12/7/06, pieter coussement  wrote:
>
> ok the blending is what it is.
> Another stupid question I'm sure but looked into it and can't figure out what to do.
>
> I have two movies one comes from a jit.qt and is rendered on a jit.gl.videoplane the other comes from a jit.matrix and I am using a submatrix to 'fly over the image' It's a picture of random vertical lines in some freaky fluo colours.
>
> I want' to make that all that is black becomes transparent, I've read the forum, finding some examples with using alpha layers (which isn't an option I think) and am pretty shure I understand out of reading things about blendingmodes on the gl website it can be done to make everything that is black or has less luminance transparent (or in an advanced way more transparent)
>
> It's just that I guess I am just to stupid to figure this out.
>
> I have depth_enable turned off, because I read somewhere this shoud be off
>
> apart from that I'm kind of lost
>
> best regards and thx in advance
>
> pieter
>


I did but it doesn't seem to work, there is something I'm doing wrong but have no clue what it is, will be neeeding a point to poit drawing book for xmas.

here is the patch I'm working on, maybe I miss something obvious here, I have a lot of bpatchers and don't know if they get embeded or not.

Here's the technique. I'll let you figure out how to incorporate it

Here's the technique.  I'll let you figure out how to incorporate it
in your patch.

still not really seeing what is happening, but I'm sure I'll get the 

EUREKA, oh boy I'm stupid feeling really soon

On 07 Dec 2006, at 10:48, Wesley Smith wrote:

still not really seeing what is happening, but I'm sure I'll get the  
EUREKA, oh boy I'm stupid feeling really soon

is there a comprehensive reference for blend modes anywhere?

On Dec 7, 2006, at 3:50 AM, Wesley Smith wrote:

> Have you tried fiddling with the @blend_mode attribute? For instance,

> I often use @blend_mode 6 1 for additive blending meaning things that

> are black on top are transparent to non-black things below.

>> Another stupid question I'm sure but looked into it and can't 

>> I have two movies one comes from a jit.qt and is rendered on a 

>> jit.gl.videoplane the other comes from a jit.matrix and I am using 

>> a submatrix to 'fly over the image' It's a picture of random 

>> vertical lines in some freaky fluo colours.

>> I want' to make that all that is black becomes transparent, I've 

>> read the forum, finding some examples with using alpha layers 

>> (which isn't an option I think) and am pretty shure I understand 

>> out of reading things about blendingmodes on the gl website it can 

>> be done to make everything that is black or has less luminance 

>> transparent (or in an advanced way more transparent)

>> It's just that I guess I am just to stupid to figure this out.

>> I have depth_enable turned off, because I read somewhere this 

> Have you tried fiddling with the @blend_mode attribute?  For instance,
> I often use @blend_mode 6 1 for additive blending meaning things that
> are black on top are transparent to non-black things below.
>
> wes
>
> On 12/7/06, pieter coussement  wrote:
>>
>> ok the blending is what it is.
>> Another stupid question I'm sure but looked into it and can't  
>> figure out what to do.
>>
>> I have two movies one comes from a jit.qt and is rendered on a  
>> jit.gl.videoplane the other comes from a jit.matrix and I am using  
>> a submatrix to 'fly over the image' It's a picture of random  
>> vertical lines in some freaky fluo colours.
>>
>> I want' to make that all that is black becomes transparent, I've  
>> read the forum, finding some examples with using alpha layers  
>> (which isn't an option I think) and am pretty shure I understand  
>> out of reading things about blendingmodes on the gl website it can  
>> be done to make everything that is black or has less luminance  
>> transparent (or in an advanced way more transparent)
>>
>> It's just that I guess I am just to stupid to figure this out.
>>
>> I have depth_enable turned off, because I read somewhere this  
>> shoud be off
>>
>> apart from that I'm kind of lost
>>
>> best regards and thx in advance
>>
>> pieter
>>
>


> is there a comprehensive reference for blend modes anywhere?

josh, thank you for asking this question. i've been wondering how this works

for years and the digging you just caused me to do has caused a happy little

eureka moment. i shall now attempt to explain it all in my own words.

hopefully someone will benefit from this...

the GL Group page of the html jitter reference manual say that blend_mode

accepts a list of two integers in the range 0-10.

"The source and destination planes associated with the blend mode (default =

6 7) Blend modes are specified in the form src_blend_mode dst_blend_mode.

the 'src_blend_mode' and 'dst_blend_mode' are coefficients in the formula

used to add pixels to the frame buffer. the frame buffer is what gets sent

to your screen what you bang jit.gl.render. the source is the incoming set

of pixels to be composited and the destination is the existing set of pixels

in the frame buffer. this allows us to layer and composite many things into

the frame buffer before drawing to the screen.

(src_pixel_color*src_blend_mode) + (dst_pixel_color*dst_blend_mode) =

(incoming-pixel * scaling-factor-for-incoming-pixel) + (existing-pixel *

scaling-factor-for-existing-pixel) = new existing pixel in the frame buffer

so with our default @blend_mode 6 7, the formula would look like this:

(incoming-pixel * incoming-pixel-alphachannel) + (existing-pixel * (1 -

incoming-pixel-alphachannel)) = new existing pixel in the frame buffer

the scaling factor for our incoming pixels is our incoming alpha channel,

and the scaling factor for our existing pixels is an inverted version of the

incoming alpha channel. this is same formula that's used in jitter tutorial

9 (More Mixing), except that the alpha channel defines a separate mix factor

(scaling factor, fade amount, etc..) for each pixel.

for wes's @blend_mode 6 1, the formula would look like this:

(incoming-pixel * incoming-pixel-alphachannel) + (existing-pixel * 1) = new

for further reading, check out these tutorials and the pages links from

http://jerome.jouvie.free.fr/OpenGl/Lessons/Lesson3.php

http://jerome.jouvie.free.fr/OpenGl/Tutorials/Tutorial9.php

and here's a patch that uses @blend_mode 2 0 and @blend_mode 6 7 to make one

thanks for reading if you made it this far :)

On 12/8/06, joshua goldberg  wrote:
>
> is there a comprehensive reference for blend modes anywhere?
>

josh, thank you for asking this question. i've been wondering how this works
for years and the digging you just caused me to do has caused a happy little
eureka moment. i shall now attempt to explain it all in my own words.
hopefully someone will benefit from this...

the GL Group page of the html jitter reference manual say that blend_mode
accepts a list of two integers in the range 0-10.

quote:
"The source and destination planes associated with the blend mode (default =
6 7) Blend modes are specified in the form src_blend_mode dst_blend_mode.
The supported modes are:
0 = zero
1 = one
2 = destination color
3 = source color
4 = one minus destination color
5 = one minus source color
6 = source alpha
7 = one minus source alpha
8 = destination alpha
9 = one minus destination alpha
10 = source alpha saturate"

the 'src_blend_mode' and 'dst_blend_mode' are coefficients in the formula
used to add pixels to the frame buffer. the frame buffer is what gets sent
to your screen what you bang jit.gl.render. the source is the incoming set
of pixels to be composited and the destination is the existing set of pixels
in the frame buffer. this allows us to layer and composite many things into
the frame buffer before drawing to the screen.

the pixel blending formula is:
    (src_pixel_color*src_blend_mode) + (dst_pixel_color*dst_blend_mode) =
frame_buffer a.k.a. new dst_pixel_color

or in natural language:
(incoming-pixel * scaling-factor-for-incoming-pixel) + (existing-pixel *
scaling-factor-for-existing-pixel) = new existing pixel in the frame buffer

so with our default @blend_mode 6 7, the formula would look like this:
(incoming-pixel * incoming-pixel-alphachannel) + (existing-pixel * (1 -
incoming-pixel-alphachannel)) = new existing pixel in the frame buffer

the scaling factor for our incoming pixels is our incoming alpha channel,
and the scaling factor for our existing pixels is an inverted version of the
incoming alpha channel. this is same formula that's used in jitter tutorial
9 (More Mixing), except that the alpha channel defines a separate mix factor
(scaling factor, fade amount, etc..) for each pixel.

for wes's @blend_mode 6 1, the formula would look like this:
(incoming-pixel * incoming-pixel-alphachannel) + (existing-pixel * 1) = new
existing pixel in the frame buffer

for further reading, check out these tutorials and the pages links from
them:
http://jerome.jouvie.free.fr/OpenGl/Lessons/Lesson3.php
http://jerome.jouvie.free.fr/OpenGl/Tutorials/Tutorial9.php

and here's a patch that uses @blend_mode 2 0 and @blend_mode 6 7 to make one
movie mask the other:

thanks for reading if you made it this far :)
-jonathan

gl color attribute and transparency