I would like to know what does the tan angle of field of view does. I have seen the following line of code which I'm trying to better understand,
float fovLeft = Mathf.Tan(-outerFieldOfView * Math.PI / 180);
float fovTop = Mathf.Tan(-upperFieldOfView * Math.PI / 180);
float fovRight = Mathf.Tan(-innerFieldOfView * Math.PI / 180);
float fovBottom = Mathf.Tan(-lowerFieldOfView * Math.PI / 180);
whereas outerFieldOfView is in degrees towards the side of the screen. I suppose that it is used to find the angle of view. is my understanding right? what exactly the tan of the field of view refer to?
Following what parameters you know, the tangent could give the angle or deep or size of FOV:
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