[jitter] first shader

make sure your output geometry has blend_enable 1 ;

sosomething like jit.gl.videoplane context @blend_enable 1

:)

On Nov 8, 2007, at 2:19 PM, marius schebella wrote:

> thank you for the quick reply.
> I think I have a problem in my max patch, because
> even
> void main()
> {
>    vec4 A = texture2DRect(image, texcoord);
>    A.a = 0.4;
>    gl_FragColor = A;
> }
> does not look transparent. (A.r, A.g, A.b all work.)
> do I need a special object or argument to turn alphachannel  
> computation on? sorry if that is a basic question. right now I am  
> only using jit.qt.movie,  jit.gl.slab and jit.gl.videoplane.
> thanks,
> marius.
>
> Wesley Smith wrote:
>>  vec4 A = texture2DRect(image, texcoord);
>>    A.a = pass_other[0];
>> this should be :
>>  vec4 A = texture2DRect(image, texcoord);
>>    A.a = pass_other.x;
>> wes
>> On 11/8/07, marius schebella <marius.schebella at gmail.com> wrote:
>>> hey,
>>> I just subscribed to the jitter list, trying to test a shader but
>>> something is wrong. I hope it is ok, if I just paste it.
>>> I have to say that this is my first shader, so it could be some very
>>> basic problem with bindings or jitter communication.
>>> anyway, when I try to load the shader I get:
>>> setting GLSL param: GL Error: Invalid operation
>>> thanks for help,
>>> marius.
>>>
>>> ---------
>>> <jittershader name="set-alpha">
>>>        <description>Shader to set alpha related to color  
>>> thresholds</description>
>>>        <param name="image" type="float" default="0" />
>>>        <param name="hithresh" type="vec4" default="0.0 0.0 0.0  
>>> 0.0" />
>>>        <param name="lothresh" type="vec4" default="0.0 0.0 0.0  
>>> 0.0" />
>>>        <param name="pass_other" type="vec2" default="0.0 1.0" />
>>>        <language name="glsl" version="1.0">
>>>                <bind param="image" program="fp" />
>>>                <bind param="hithresh" program="fp" />
>>>                <bind param="lothresh" program="fp" />
>>>                <bind param="pass_other" program="fp" />
>>>
>>>        <program name="vp" type="vertex">
>>> <![CDATA[
>>> // VERTEX SHAADER
>>>
>>> varying vec2 texcoord;
>>>
>>> void main (void)
>>> {
>>>     gl_Position = ftransform();
>>>     texcoord    = vec2(gl_TextureMatrix[0] * gl_MultiTexCoord0);
>>> }
>>> ]]>
>>>        </program>
>>>
>>>        <program name="fp" type="fragment">
>>> <![CDATA[
>>> // FRAGMENT SHADER
>>>
>>> varying vec2 texcoord;
>>> uniform sampler2DRect image;
>>>
>>> uniform vec4 hithresh;    // hi and lo threshold
>>> uniform vec4 lothresh;
>>> uniform vec2 pass_other;
>>>
>>> void main()
>>> {
>>>     vec4 A = texture2DRect(image, texcoord);
>>>     A.a = pass_other[0];
>>>     if ((A.r >= hithresh.r) || (A.r <= lothresh.r) || (A.g >=  
>>> hithresh.g)
>>>                || (A.g <= lothresh.g) || (A.b >= hithresh.b) ||  
>>> (A.r <= lothresh.b))
>>>        {
>>>                A.a = pass_other[1];
>>>        }
>>>     gl_FragColor = A;
>>>
>>> }
>>> ]]>
>>>        </program>
>>>        </language>
>>> </jittershader>
>>> _______________________________________________
>>> jitter mailing list
>>> jitter at cycling74.com
>>> http://www.cycling74.com/mailman/listinfo/jitter
>>>
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