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optimize GetOutlineCameraFovAndDistanceFixMultiplier #10

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optimize GetOutlineCameraFovAndDistanceFixMultiplier #10

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23 changes: 17 additions & 6 deletions NiloOutlineUtil.hlsl
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Original file line number Diff line number Diff line change
Expand Up @@ -6,13 +6,19 @@
// If your project has a faster way to get camera fov in shader, you can replace this slow function to your method.
// For example, you write cmd.SetGlobalFloat("_CurrentCameraFOV",cameraFOV) using a new RendererFeature in C#.
// For this tutorial shader, we will keep things simple and use this slower but convenient method to get camera fov
float GetCameraFOV()
float GetFOVFactor()
{
//https://answers.unity.com/questions/770838/how-can-i-extract-the-fov-information-from-the-pro.html
float t = unity_CameraProjection._m11;
/*float t = unity_CameraProjection._m11;
float Rad2Deg = 180 / 3.1415;
float fov = atan(1.0f / t) * 2.0 * Rad2Deg;
return fov;
float fov = atan(1.0f / t) * 2.0 * Rad2Deg;*/

//unity_CameraProjection._m11 is actually cot(FOV),
//so 1/unity_CameraProjection._m11 is tan(FOV), which is (Size of View Plane / Distance to Object)
//in this use case, if our change of FOV cause size of view plane (in world space) become 2x, we want our outline to also become 2x to compensate this change,
//and make the outline width same with original
//converting it back to FOV angle cause some lost of accuracy and speed
return (1.0f/unity_CameraProjection._m11);
}
float ApplyOutlineDistanceFadeOut(float inputMulFix)
{
Expand All @@ -30,12 +36,17 @@ float GetOutlineCameraFovAndDistanceFixMultiplier(float positionVS_Z)

// keep outline similar width on screen accoss all camera distance
cameraMulFix = abs(positionVS_Z);
// keep outline similar width on screen accoss all camera fov
// this is done BEFORE OutlineDistanceFadeOut because, for example,
// a character 1m away from camera with fov of 90
// appears the same size in camera as a character sqrt(3)m away from camera with fov of 60
cameraMulFix *= GetFOVFactor();

// can replace to a tonemap function if a smooth stop is needed
cameraMulFix = ApplyOutlineDistanceFadeOut(cameraMulFix);

// keep outline similar width on screen accoss all camera fov
cameraMulFix *= GetCameraFOV();
//to match the outline with before this optimization. Should actually be 180 / 3.1415 (Rad2Deg), but 60 will do
cameraMulFix *= 60;
}
else
{
Expand Down