/**
|
* Computes a value that scales with distance. The scaling is clamped at the near and
|
* far distances, and does not extrapolate. This function works with the
|
* {@link NearFarScalar} JavaScript class.
|
*
|
* @name czm_nearFarScalar
|
* @glslFunction
|
*
|
* @param {vec4} nearFarScalar A vector with 4 components: Near distance (x), Near value (y), Far distance (z), Far value (w).
|
* @param {float} cameraDistSq The square of the current distance from the camera.
|
*
|
* @returns {float} The value at this distance.
|
*/
|
float czm_nearFarScalar(vec4 nearFarScalar, float cameraDistSq)
|
{
|
float valueAtMin = nearFarScalar.y;
|
float valueAtMax = nearFarScalar.w;
|
float nearDistanceSq = nearFarScalar.x * nearFarScalar.x;
|
float farDistanceSq = nearFarScalar.z * nearFarScalar.z;
|
|
float t = (cameraDistSq - nearDistanceSq) / (farDistanceSq - nearDistanceSq);
|
|
t = pow(clamp(t, 0.0, 1.0), 0.2);
|
|
return mix(valueAtMin, valueAtMax, t);
|
}
|
