GLSL texture returns zero after OpenInventor upgrade from 9.8 to 10.4.2

Question

While upgrading our source code from OpenInventor 9.8 to 10.4.2 I encountered that some color computed in the fragment-shader is always black in 10.4.2 while in 9.8 everything works fine. Normally we use our own computed texture, but for debugging purposes I used an example texture from the OpenInventor examples:

SoSwitch* root = new SoSwitch;
// Fill root with geometry
root->addChild(...)

SoSeparator* localRoot = new SoSeparator;
SoFragmentShader* fragShader = new SoFragmentShader;
SoShaderProgram* shaderProgram = new SoShaderProgram;

SoTexture2 texture = new SoTexture2;
texture->filename = "pathToImage\image.png"

SoTextureUnit textureUnit = new SoTextureUnit;
texture Unit->unit = 1;

localRoot->addChild(textureUnit);
localRoot->addChild(texture);

fragShader->addShaderParameter1i("myTexture", 1);
shaderProgram->shaderObject.set1Value(1, fragShader);

root->addChild(localRoot);
root->addChild(shaderProgram);

This is the fragment-shader which works fine with 9.8:

#version 120
uniform sampler2D myTexture;
in vec3 coord; // Computed in vertex-shader
int main() {
    gl_FragColor = texture2D(myTexture, coord.xy);
    // For Debugging:
    // gl_FragColor = vec4(coord.xy, 0, 1);
}

This is the fragment-shader which does not work with 10.4.2:

#version 410 compatibility
//!oiv_include <Inventor/oivShaderState.h>
//!oiv_include <Inventor/oivShapeAttribute.h>
//!oiv_include <Inventor/oivShaderVariables.h>
uniform sampler2D myTexture;
in vec3 coord;
int main() {
    OivFragmentOutput(texture(myTexture, coord.xy)); // Is the same as gl_FragColor = 
    // For Debugging:
    // gl_FragColor = vec4(coord.xy, 0, 1);
}

The viewer stays completely black, so I assume the call to texture returns always zero. Uncommenting gl_FragColor = vec4(coord.xy, 0, 1); gives the same result. Therefor I assume that coordis computed correctly.

As we are jumping from version #120 to #410, I could imagine that I need to do something else to get texture work in our fragment-shader. Were there any relevant changes in GLSL. What do I need to do to get the shader working?

If relevant, here are some system information:

Operating System: Windows 10
Graphics board: NVIDIA Quadro K2200

score 3 · Accepted Answer · answered Feb 26 '20 at 19:46

The issue here is in your scene graph as both texture and textureUnit nodes are under a SoSeparator and are not visible to the shaderProgam, which is outside the SoSeparator localRoot. Please move these nodes out of localRoot and add them as a child to the root node to render correctly.

It was working for you with Open Inventor 9.8 because of a bug which is fixed since Open Inventor 10. Hope this helps and let us know if the issue is resolved for you.

In future, please feel free to contact Open Inventor support ( FRBOR.3d_hotline@thermofisher.com) with your questions.

score 2 · Answer 2 · answered Feb 27 '20 at 15:38

2

Via mail the Open Inventor Support suggested another solution which is also working:

Replace

SoSeparator* localRoot = new SoSeparator;

with

SoGroup* localRoot = new SoGroup;

answered Feb 27 '20 at 15:38

Dragoner

123
1
12

1

That would work as well because SoGroup unlike SoSeparator does not save and restore traversal state, which means your texture nodes are visible to rest of the scene graph after *localRoot*. – Bidur Feb 28 '20 at 14:59

GLSL texture returns zero after OpenInventor upgrade from 9.8 to 10.4.2

2 Answers2