shader3/res/shader/edge_detect.fs

varying vec2 V_Texcoord;

uniform sampler2D U_MainTexture;

void main()
{
	//1 2 1
	//2 4 2
	//1 2 1
	vec4 color = vec4(0.0);
	int coreSize = 3;
	float texelOffset = 1/150.0;
	float kernel[9];

	kernel[6]=0;kernel[7]=1;kernel[8]=0;
	kernel[3]=1;kernel[4]=-4;kernel[5]=1;
	kernel[0]=0;kernel[1]=1;kernel[2]=0;

	int index = 0;
	for(int y=0; y<coreSize; y++){
		for(int x=0; x<coreSize; x++){
			vec4 currentColor = texture2D(U_MainTexture, V_Texcoord+vec2((-1+x)*texelOffset, (-1+y)*texelOffset));
			color += currentColor*kernel[index++];
		}
	}
	gl_FragColor=4.0*color+texture2D(U_MainTexture,V_Texcoord);
}