Output shaders are called after the image has been computed. An output shader can use the function mi_get_contour_line to get endpoints of a contour. When mi_get_contour_line returns miFALSE, there are no more contour lines.
Here is a very simple output shader that prints the screen-space coordinates of the contour endpoints.
miBoolean my_contour_output_shader( miColor *result, /* unused */ miState *state) /* no parameters */ { miContour_endpoint p1; miContour_endpoint p2; mi_info("Contour endpoints:"); /* Get and write the contour endpoints */ while (mi_get_contour_line(&p1, &p2)) mi_info("%f %f --- %f %f", p1.point.x, p1.point.y, p2.point.x, p2.point.y); return(miTRUE); }
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