android - OpenGL ES 2.0 getAttributeLocation returning -1 -

i'm attempting color object in opengl es 2.0 android when call following returns -1.

int mcolorhandle = gles20.getattributelocation(mprogram,"icolor"); 

shader:

private static final string sfragmentshadercode = "precision mediump float;"         + "uniform vec4 icolor;"         + "void main() {"         + " gl_fragcolor = icolor;" + "}"; 

method call in context:

mprogram = gles20.glcreateprogram();  gles20.glattachshader(mprogram, vertexshader); gles20.glattachshader(mprogram, fragshader); gles20.gllinkprogram(mprogram);  int mcolorhandle = gles20.getattributelocation(mprogram,"icolor"); log.i(tag,"mcolorhandle: "+integer.tostring(mcolorhandle)); 

any idea causing this?

you've declared icolor uniform, you'll need call gles20.glgetuniformlocation(mprogram,"icolor") if you're using uniform variable (which say, 1 icolor value many different primitives).

if have buffer of icolor values, 1 each vertex, you'll need declare icolor "attrib vec4 icolor;" in shader. after that, call gles20.glgetattributelocation(mprogram,"icolor") should return valid location.