Hi  Jpct Community,

     Recently I was fiddling with Jpct's renderToTexture... and I wanted to do some Sobel filter to a texture for edge detection for a nice toony effect.
So I did this->
                fb.setRenderTarget(targetTexture);
fb.setBlittingShader(shader);
fb.clear(RGBColor.BLUE);
world.renderScene(fb);
world.draw(fb);
fb.display();
fb.removeRenderTarget();


fb.blit(targetTexture, srcX, srcY, destX, destY, sourceWidth, sourceHeight, destWidth, destHeight, -1, false);

blitNumber(lfps, 5, 5);
fb.display();

and this is the fragment shader I intend to apply on the texture->
(copied from internet) ->
in vec2 TexCoords;
out vec4 color;

uniform sampler2D screenTexture;

mat3 sx = mat3(
    1.0, 2.0, 1.0,
    0.0, 0.0, 0.0,
   -1.0, -2.0, -1.0
);
mat3 sy = mat3(
    1.0, 0.0, -1.0,
    2.0, 0.0, -2.0,
    1.0, 0.0, -1.0
);

void main()
{
   vec3 diffuse = texture(screenTexture, TexCoords.st).rgb;
    mat3 I;
    for (int i=0; i<3; i++) {
        for (int j=0; j<3; j++) {
            vec3 sample  = texelFetch(screenTexture, ivec2(gl_FragCoord) + ivec2(i-1,j-1), 0 ).rgb;
           I[i][j] = length(sample);
    }
}

float gx = dot(sx[0], I[0]) + dot(sx[1], I[1]) + dot(sx[2], I[2]);
float gy = dot(sy[0], I[0]) + dot(sy[1], I[1]) + dot(sy[2], I[2]);

float g = sqrt(pow(gx, 2.0)+pow(gy, 2.0));
color = vec4(diffuse - vec3(g), 1.0);
}


     I guess that we dont have that "texelFetch()" in opengles 2.0  . So do we have any alternate for this?
Or any pointer to a different approach ?
     I am new to 3d programming and trying to experiment with different concepts . I would like to make a 3d game for android,
I found Jpct-ae and I loved its simplicity