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Multiple textures with Mali-GPUs don't work properly

Dominik Bar
Note: This was originally posted on 6th February 2013 at http://forums.arm.com

Hi,

I have a problem with Mali-GPUs and multiple textures with OpenGL ES 2 (at least, I think it could be a problem with the Mali-GPU).

So, here my problem:
I just want to use multiple textures in my Android-App with OpenGL-ES 2.0, but the necessary code in the fragment shader doesn't work with most Samsung devices (tested Galaxy Nexus, galaxy S3, Galaxy Note 2, Galaxy S2). The texture wich is new calculated in the fragment shader (see code below), doesn't show up on this devices, but on the Nexus 4, it works fine. So, I conclude, that this problem could be caused by the Mali-GPU in the Samsung devices.

Here the fragment shader code I am using:
precision mediump float;            
uniform sampler2D uTexture;
uniform sampler2D refractTexture;   
varying vec2 vTexCoordinate;
varying vec2 vRefTexCoordinate;

void main() {  
   vec2 scaleVec = vec2(0.05, 0.05); 
      vec4 bumpTex = 2.0 * texture2D(refractTexture, vRefTexCoordinate) - 1.0; 
   vec2 refCoords = vTexCoordinate.xy + bumpTex.xy * scaleVec; 

    gl_FragColor = texture2D(uTexture, refCoords);

}

The error seems to be in following line:
vec4 bumpTex = 2.0 * texture2D(refractTexture, vRefTexCoordinate) - 1.0;
If I delete this line (and the follwing line vec2 refCoords =...), the texture appears (it's just not calculated, but at least, it is visible). I have no idea, why this works on a Nexus 4, but not on a Mali-device.

Are there any known problems wiht the texture2d()-function on the Mali-GPUs or is it just my fault (but, how I said, on other non-mali devices it works properly)?

I would be glad about any tips and support relating to my problem.
Parents
  • Note: This was originally posted on 8th February 2013 at http://forums.arm.com

    Hi,

    thanks for your answer.
    I have tested some devices. Here a list with the OS/rom:
    - Samsung galaxy S3, 4.1.2, samsung firmware (root)
    - Samsung galaxy Note 2, 4.1.2, samsung firmware (root)
    - Samsung Galaxy S2, 2.3, samsung firmware (no root)
    - Samsung Galaxy Nexus, 4.2, stock android (no root)

    on all this devices the texture, that was recalculated in the fragment shader with this two lines:
      vec4 bumpTex = 2.0 * texture2D(refractTexture, vRefTexCoordinate) - 1.0; 
            vec2 refCoords = vTexCoordinate.xy + bumpTex.xy * scaleVec; 


    was not visible. But on the LG Nexus 4 (Adreno 320 GPU), it works. If i delete the two lines from above in my shader code, the normal texture is visible on all devices....

    I will have a look, whether I could make a project where the error is repoducible (actual project is quite large)
Reply
  • Note: This was originally posted on 8th February 2013 at http://forums.arm.com

    Hi,

    thanks for your answer.
    I have tested some devices. Here a list with the OS/rom:
    - Samsung galaxy S3, 4.1.2, samsung firmware (root)
    - Samsung galaxy Note 2, 4.1.2, samsung firmware (root)
    - Samsung Galaxy S2, 2.3, samsung firmware (no root)
    - Samsung Galaxy Nexus, 4.2, stock android (no root)

    on all this devices the texture, that was recalculated in the fragment shader with this two lines:
      vec4 bumpTex = 2.0 * texture2D(refractTexture, vRefTexCoordinate) - 1.0; 
            vec2 refCoords = vTexCoordinate.xy + bumpTex.xy * scaleVec; 


    was not visible. But on the LG Nexus 4 (Adreno 320 GPU), it works. If i delete the two lines from above in my shader code, the normal texture is visible on all devices....

    I will have a look, whether I could make a project where the error is repoducible (actual project is quite large)
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