obs-shaderfilter-plus-shaders/red_alert.glsl

float4 render(float2 uv) {
	int iTime = int(builtin_elapsed_time_since_shown);
	float4 image_color = image.Sample(builtin_texture_sampler, uv);
	float red = (builtin_elapsed_time_since_shown - iTime);
	red = red > 0.5 ? 1 - red : red;
	image_color[0] = image_color[0] + red * 0.7;
	return image_color;
}