Pixel-Composer/scripts/blurSurface/blurSurface.gml

function surface_apply_gaussian(surface, size, bg = false, bg_c = c_white, clamp_border = false) {
	static uni_bor = shader_get_uniform(sh_blur_gaussian, "clamp_border");
	static uni_dim = shader_get_uniform(sh_blur_gaussian, "dimension");
	static uni_hor = shader_get_uniform(sh_blur_gaussian, "horizontal");
	static uni_wei = shader_get_uniform(sh_blur_gaussian, "weight");
	static uni_sze = shader_get_uniform(sh_blur_gaussian, "size");
	
	var hori = surface_create_valid(surface_get_width(surface), surface_get_height(surface));	
	var vert = surface_create_valid(surface_get_width(surface), surface_get_height(surface));	
	
	size = max(1, round(size));
	var gau_array = array_create(size);
	var we = 0;
	var b  = 0.3 * ((size - 1) * 0.5 - 1) + 0.8;
	for(var i = 0; i < size; i++) {
		var _x = i * .5;
		
		gau_array[i] = (1 / sqrt(2 * pi * b)) * exp( -sqr(_x) / (2 * sqr(b)) );
		we += i? gau_array[i] * 2 : gau_array[i];
	}
	for(var i = 0; i < size; i++) {
		gau_array[i] /= we;
	}
	
	surface_set_target(hori);
		draw_clear_alpha(bg_c, bg);
		
		shader_set(sh_blur_gaussian);
		shader_set_uniform_f_array(uni_dim, [ surface_get_width(surface), surface_get_height(surface) ]);
		shader_set_uniform_f_array(uni_wei, gau_array);
		
		shader_set_uniform_i(uni_bor, clamp_border? 1 : 0);
		shader_set_uniform_i(uni_sze, size);
		shader_set_uniform_i(uni_hor, 1);
		
		draw_surface_safe(surface, 0, 0);
		shader_reset();
	surface_reset_target();
	
	surface_set_target(vert);
		draw_clear_alpha(bg_c, bg);
		
		shader_set(sh_blur_gaussian);
		shader_set_uniform_i(uni_hor, 0);
		
		draw_surface_safe(hori, 0, 0);
		shader_reset();
	surface_reset_target();
	
	surface_free(hori);
	
	return vert;
}