1 files changed, 47 insertions, 0 deletions
diff --git a/examples/06_GPU_opticalflow/of.frag b/examples/06_GPU_opticalflow/of.frag
new file mode 100644
index 0000000..af7d99e
--- /dev/null
+++ b/examples/06_GPU_opticalflow/of.frag
@@ -0,0 +1,47 @@
+#extension GL_ARB_texture_rectangle : enable
+
+uniform sampler2DRect currentFrame, previousFrame;
+uniform float lambda;
+uniform vec2 scale;
+
+vec2 offset = vec2(1.,1.);
+vec2 texcoord0 = gl_TexCoord[0].st;
+vec2 texcoord1 = gl_TexCoord[1].st;
+
+void main()
+{   
+	vec4 a = texture2DRect(currentFrame, texcoord0);
+	vec4 b = texture2DRect(previousFrame , texcoord1);
+	vec2 x1 = vec2(offset.x,0.);
+	vec2 y1 = vec2(0.,offset.y);
+
+	//get the difference
+	vec4 curdif = b-a;
+	
+	//calculate the gradient
+	vec4 gradx = texture2DRect(previousFrame, texcoord1+x1)-texture2DRect(previousFrame, texcoord1-x1);
+	gradx += texture2DRect(currentFrame, texcoord0+x1)-texture2DRect(currentFrame, texcoord0-x1);
+	vec4 grady = texture2DRect(previousFrame, texcoord1+y1)-texture2DRect(previousFrame, texcoord1-y1);
+	grady += texture2DRect(currentFrame, texcoord0+y1)-texture2DRect(currentFrame, texcoord0-y1);
+	vec4 gradmag = sqrt((gradx*gradx)+(grady*grady)+vec4(lambda));
+	
+	if ( gradmag.r == 0. ) {
+		gl_FragColor = vec4(0.5,0.5,0.5,1);
+		return;
+	}
+
+	vec4 vx = curdif*(gradx/gradmag);
+	float vxd = vx.r;//assumes greyscale
+	//format output for flowrepos, out(-x,+x,-y,+y)
+	//~ vec2 xout = vec2(max(vxd,0.),abs(min(vxd,0.)))*scale.x;
+	float xout = ((vxd/2.)*scale.x+0.5);
+
+	vec4 vy = curdif*(grady/gradmag);
+	float vyd = vy.r;//assumes greyscale
+	//format output for flowrepos, out(-x,+x,-y,+y)
+	//~ vec2 yout = vec2(max(vyd,0.),abs(min(vyd,0.)))*scale.y;
+	float yout = ((vyd/2.)*scale.y+0.5);
+	
+	//~ gl_FragColor = vec4(xout.xy,yout.xy);
+	gl_FragColor = vec4(xout,yout,0.5,1.);
+}