[osg-users] Text colors in shaders

[Werner Modenbach]

Hi Sebastian,

that's great. It works with the shader you suggested.
Strange is, that just using vertex color doesn't work. It seems alpha is 
set to transparent (0).
Also a texture is set but only alpha has a meaning. Texture color is black.
That looks odd to me.

But anyway, I'm happy now.

- Werner -

Am 24.02.2017 um 13:16 schrieb Sebastian Messerschmidt:
>
>
> Am 2/24/2017 um 12:57 PM schrieb Werner Modenbach:
>> Dear all,
>>
>> my project needs gl3 features and so I use the following methods:
>>
>>
>> camera->getGraphicsContext()->getState()->setUseModelViewAndProjectionUniforms(useGL3); 
>>
>>
>> camera->getGraphicsContext()->getState()->setUseVertexAttributeAliasing(useGL3); 
>>
>>
>> Of course I need my own shaders then.
>> But I also like having built-in functionality like StatsHandler.
>> To set a simple shader for the StatsHandlers camera I do like that:
>>
>> osgViewer::StatsHandler*sthd=newosgViewer::StatsHandler;
>>
>> view->addEventHandler(sthd);
>>
>> if(useGL3){
>> stateSet=sthd->getCamera()->getOrCreateStateSet();
>>
>> stateSet->getOrCreateUniform(BASE_TEXTURE_UNIFORM,osg::Uniform::INT_SAMPLER_2D)->set(BASE_TEXTURE_UNIT); 
>>
>>
>> stateSet->setTextureAttributeAndModes(BASE_TEXTURE_UNIT,textur_weiss.get(),osg::StateAttribute::ON); 
>>
>>
>> installDefaultShader(stateSet);
>>
>> }
>>
>> The shaders are really simple:
>> VERTEX
>>
>> uniformmat4osg_ModelViewProjectionMatrix;
>> uniformmat4osg_ModelViewMatrix;
>>
>> uniformmat3osg_NormalMatrix;
>>
>> uniformvec3lightPosition0=vec3(0.0f,0.0f,1.0f);
>>
>> invec4osg_Vertex;
>>
>> invec4osg_Normal;
>>
>> invec4osg_Color;
>>
>> invec4osg_MultiTexCoord0;
>>
>> outvec3normal;
>>
>> outvec3lightDir;
>>
>> outvec4vertexColor;
>>
>> outvec2textureCoord;
>>
>> voidmain(){
>>
>> normal=normalize(osg_NormalMatrix*osg_Normal.xyz);
>>
>> vec3vertexPos=vec3(osg_ModelViewMatrix*osg_Vertex);
>>
>> lightDir=normalize(lightPosition0-vertexPos);
>>
>> vertexColor=osg_Color;
>>
>> textureCoord=osg_MultiTexCoord0.xy;
>>
>> gl_Position=osg_ModelViewProjectionMatrix*osg_Vertex;
>>
>> }
>>
>>
>> FRAGMENT
>>
>> uniformsampler2DbaseTexture;
>>
>> invec3normal;
>> invec3lightDir;
>>
>> invec4vertexColor;
>>
>> invec2textureCoord;
>>
>> outvec4fragData;
>>
>> voidmain(){
>>
>>     vec4textureColor=texture2D(baseTexture,textureCoord);
>> fragData=vertexColor*textureColor;
>>
>> }
>>
>>
>> That works fine for the graphics but all text is black. Obviously text
>> does not set osg_Color .
>
> osg_Color is an alias for the color-vertex attribute. Colors are set in
> void Text::drawForegroundText ~line 1628. So there should be colors.
>
> My fragment shader looks like this:
>
> #version 440
> #extension GL_ARB_enhanced_layouts : enable
> #extension GL_ARB_separate_shader_objects : enable
>
> layout (location=0) out vec4 FragmentData;
>
> layout(location=1) in block
> {
>     mediump vec2 tex_coord;
>     mediump vec4 color;
> } In;
>
>
> uniform sampler2D osg_Texture;
>
> void main()
> {
>
>     vec4 diffuse_color = In.color;
>
>     diffuse_color *=  texture2D(osg_Texture, In.tex_coord).a;
>
>     FragmentData = diffuse_color;
> }
>
> which seems to work. As you can see I'm using the alpha channel only.
>
> Cheers
> Sebastian
>
>
>> Unfortunately I failed discovering the reason in the sources of osg.
>>
>> Can anyone give me a hint on how to solve this?
>>
>> Many thanks in advance
>>
>> - Werner -
>>
>>
>>
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>>
>>
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