31 lines
943 B
Plaintext
31 lines
943 B
Plaintext
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#define SHIFT_RIGHT_8 0.00390625 //1.0 / 256.0
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#define SHIFT_RIGHT_16 0.00001525878 //1.0 / 65536.0
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#define SHIFT_RIGHT_24 5.960464477539063e-8//1.0 / 16777216.0
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#define BIAS 38.0
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/**
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* Unpacks a vec4 value containing values expressable as uint8 to an arbitrary float.
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*
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* @name czm_unpackFloat
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* @glslFunction
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*
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* @param {vec4} packedFloat The packed float.
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*
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* @returns {float} The floating-point depth in arbitrary range.
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*/
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float czm_unpackFloat(vec4 packedFloat)
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{
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packedFloat *= 255.0;
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float temp = packedFloat.w / 2.0;
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float exponent = floor(temp);
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float sign = (temp - exponent) * 2.0;
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exponent = exponent - float(BIAS);
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sign = sign * 2.0 - 1.0;
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sign = -sign;
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float unpacked = sign * packedFloat.x * float(SHIFT_RIGHT_8);
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unpacked += sign * packedFloat.y * float(SHIFT_RIGHT_16);
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unpacked += sign * packedFloat.z * float(SHIFT_RIGHT_24);
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return unpacked * pow(10.0, exponent);
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}
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