renderProgram debugTools/showTexelDensity {
	
	program vertex glsl { <%
		
		attribute vec4 $texCoordAttrib;
		varying	vec4 texcoord0;
		void main()
		{
			gl_Position = ftransform();
			texcoord0 = $texCoordAttrib;
		}
	%> }
	
	program fragment glsl { <%
	
		uniform vec4 $imageSize;
		varying	vec4 texcoord0;
		void main( void ) {
			vec4 mult = $imageSize;//vec4( 4096, 4096, 1024, 1024 );
			vec4 dx = dFdx( texcoord0 * mult );
			vec4 dy = dFdy( texcoord0 * mult );
			vec4 delta = ( dx * dx + dy * dy );
			float minDelta = max( delta.x, delta.y );
			float mipLevel;
			if ( minDelta > 0.0 ) {
				mipLevel = 0.5 * log2( minDelta );
			} else {
				mipLevel = 0.0;
			}
			float l = log2( max(mult.x,mult.y) );
			int idx = int(mipLevel * l);
			gl_FragColor = vec4( mipLevel, mipLevel, mipLevel, mipLevel );
			if ( idx <= 0 ) {
				gl_FragColor = vec4(1.0,0.0,0.0,1.0);
			} 
			if ( idx == 1 ) {
				gl_FragColor = vec4(0.0,1.0,0.0,1.0);
			}
			if ( idx == 2 ) {
				gl_FragColor = vec4(0.0,0.0,1.0,1.0);
			}
			if ( idx == 3 ) {
				gl_FragColor = vec4(1.0,0.0,1.0,1.0);
			}
			if ( idx == 4 ) {
				gl_FragColor = vec4(0.0,1.0,1.0,1.0);
			}
		}
	%> }
	
}