engine/src/test/jme3test/texture/tex3DThumb.frag

uniform sampler3D m_Texture;
uniform int m_Rows;
uniform float m_InvDepth;

varying vec2 texCoord;

void main(){
float depthx=floor(texCoord.x);
    float depthy=(m_Rows-1.0) - floor(texCoord.y);    
    //vec3 texC=vec3(texCoord.x,texCoord.y ,0.7);//
  
        vec3 texC=vec3(fract(texCoord.x),fract(texCoord.y),(depthy*m_Rows+depthx)*m_InvDepth);//
    gl_FragColor= texture3D(m_Texture,texC);
}