How To Get Vertical Camera FOV

I couldn’t find how to get the vertical camera FOV value directly so I wrote this.

This shader provieds an example of how to get the vertical FOV value of the camera in either radians or degrees from the PROJECTION_MATRIX.

Also, to prove that it works, you can apply this shader to any object and it wil be white if the ‘compare_FOV’ fits the camera FOV and it will be black otherwise. I chose 70° as default as that is the default FOV in the editor.

Shader code

shader_type spatial;

uniform float compare_FOV = 70;

void fragment() {

	float FOV_in_radians = atan(-1.0 / PROJECTION_MATRIX[1][1]) * 2.0;
	float FOV_in_degrees = degrees(FOV_in_radians);

	if(FOV_in_degrees > compare_FOV - 0.1 && FOV_in_degrees < compare_FOV + 0.1)
	{
		ALBEDO = vec3(1.0,1.0,1.0);
	}
	else
	{
		ALBEDO = vec3(0.0,0.0,0.0);
	}

}

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