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