[Ves] Modify uniform variables

[Jon Chmura]

Aashish,

That solution didn't work for me but t think I have found the source of the problem.  In the KiwiViewer app the "Texture" shader is used in vesKiwiImageWidgetRepresentation. The "Texture" shader is actually vesBackgroundTexture shader not GourandTexture shader.  I believe this decision was made so that there is no shadowing when rendering 3 plane Image Volumes.  In my application I followed the same design and used vesBackgroundTexture for my image shader and GourandTexture as my geometry shader.  The problem is that the vesBackgroundTexture shader does not have a uniform for vertexOpacity.  

I'm going to solve this problem in my application by making another shader for image volumes that is identical to vesBackgroundTexture shader excepts that is adds a uniform for opacity.

Jon Chmura
jon.chmura at me.com




On Oct 15, 2013, at 10:41 PM, Aashish Chaudhary <aashish.chaudhary at kitware.com> wrote:

> Hi Jon, 
> 
> I looked into the code, basically since this is a in-built uniform the value is set using the mapper color. So in your code, if you want to use this unifrom, you can do this instead: 
> 
> In some call:
> rep->actor()->mapper()->setColor(0.1, 0.5, 0.1, 0.5);
> 
> In next call: 
> rep->actor()->mapper()->setColor(0.1, 0.5, 0.1, 0.7);
> 
> Basically change the mapper alpha) as and when you need it.  
> 
> Now, as I said earlier, you can change the shader and use our own variable names if desired. 
> 
> Let me know if this helps. 
> 
> - Aashish
> 
> 
> - Aashish
> 
> 
> 
> 
> On Tue, Oct 15, 2013 at 4:15 PM, Jon Chmura <jon.chmura at me.com> wrote:
> Aashish,
> 
> I tried setting the value of the uniform but it isn't changing.  I have been using the class vesKiwiImageWidgetRepresentation from the KiwiViewer code in my app for displaying brain volume data.  I made a modification to it so that I can test setting this value on the uniform.
> This code isn't working.  The getter always returns 1.  I placed breakpoints in this code and I have confirmed that it is finding the vertexOpacity uniform.  Does it have to be a vesEngineUniform subclass in order to set its value?  I noticed that the vesUniform class does not have the method bindRenderData
> 
> //----------------------------------------------------------------------------
> void vesKiwiImageWidgetRepresentation::setPlaneOpacity(int planeIndex, double opacity)
> {
>   assert(planeIndex >= 0 && planeIndex <= 2);
> 
>   vesShaderProgram::Ptr shader = this->Internal->SliceReps[planeIndex]->actor()->material()->shaderProgram();
>   vesUniform::Ptr uniform = shader->uniform("vertexOpacity");
> 
>   uniform->set( (float) opacity);
>   shader->updateUniforms();
> }
> 
> //----------------------------------------------------------------------------
> double vesKiwiImageWidgetRepresentation::planeOpacity(int planeIndex)
> {
>   assert(planeIndex >= 0 && planeIndex <= 2);
> 
>   float value = 0;
> 
>   vesShaderProgram::Ptr shader = this->Internal->SliceReps[planeIndex]->actor()->material()->shaderProgram();
>   vesUniform::Ptr uniform = shader->uniform("vertexOpacity");
> 
>   uniform->get(value);
> 
>   return value;
> }
> 
> 
> Thanks -
> Jon Chmura
> jon.chmura at me.com
> 
> 
> 
> 
> On Oct 15, 2013, at 10:02 AM, Aashish Chaudhary <aashish.chaudhary at kitware.com> wrote:
> 
>> Hi Jon, 
>> 
>> Please have a look at the class below. You can create a new instance of it (give it a different name) and you should be able to change its value. 
>> Looking at the code, the opacity uniform is not an engine uniform (engine uniforms are special uniforms), so you can even get it and then change its value if needed. 
>> 
>> - Aashish
>> 
>> In vesShaderProgram.cpp
>> this->addUniform(vesVertexOpacityUniform::Ptr(new vesVertexOpacityUniform));
>> 
>> in vesEngineUniform.h
>> class vesVertexOpacityUniform : public vesUniform
>> {
>> public:
>>   vesTypeMacro(vesVertexOpacityUniform);
>> 
>>   vesVertexOpacityUniform(const std::string &name="vertexOpacity") :
>>     vesUniform(name, static_cast<float>(1.0))
>>   {
>>   }
>> 
>>   virtual void update(const vesRenderState &renderState,
>>                       const vesShaderProgram &program)
>>   {
>>     vesNotUsed(program);
>>     this->set(renderState.m_mapper->color()[3]);
>>   }
>> };
>> 
>> I have to remember (or find out) why we didn't derive from vesEngineUniform for opacity, but that shouldn't really affect you. 
>> 
>> - Aashish
>> 
>> 
>> 
>> 
>> On Mon, Oct 14, 2013 at 4:24 PM, Aashish Chaudhary <aashish.chaudhary at kitware.com> wrote:
>> Dear Jon, 
>> 
>> Let me have a look at the code and will reply back. But in short, you can make your own uniform and use that in the shader, IN other words, 
>> you are bounds of engine uniforms. 
>> 
>> I thought we have an API for the engine uniforms, let me make a check on it. 
>> 
>> Thanks,
>> 
>> 
>> 
>> On Mon, Oct 14, 2013 at 2:58 PM, Jon Chmura <jon.chmura at me.com> wrote:
>> I want to set the value of vertexOpacity in vesGourandTexture shader program.
>> 
>> /// \file vesGouraudTexture_frag.glsl
>> ///
>> /// \ingroup shaders
>> 
>> uniform lowp float vertexOpacity;
>> 
>> It is given a default value of 1 in vesEngineUniform. But I can't find any accessors for it as there are for point size, line width, etc.
>> 
>> Jon Chmura
>> jon.chmura at me.com
>> 
>> 
>> 
>> 
>> 
>> _______________________________________________
>> Ves mailing list
>> Ves at public.kitware.com
>> http://public.kitware.com/cgi-bin/mailman/listinfo/ves
>> 
>> 
>> 
>> 
>> -- 
>> | Aashish Chaudhary 
>> | R&D Engineer         
>> | Kitware Inc.            
>> | www.kitware.com   
>> 
>> 
>> 
>> -- 
>> | Aashish Chaudhary 
>> | R&D Engineer         
>> | Kitware Inc.            
>> | www.kitware.com   
> 
> 
> 
> 
> -- 
> | Aashish Chaudhary 
> | R&D Engineer         
> | Kitware Inc.            
> | www.kitware.com   

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/ves/attachments/20131016/e59a8da3/attachment-0002.html>