CODEWITHSUNDEEP
javascriptthree.js
disciple
disciple

Reputation: 262

What exactly THREE.Math.mapLinear do?

I've seen an example program, in that to place the position of the Sphere they are doing some mathematical calculations. In that I've seen THREE.Math.mapLinear() is being used. If I pass the parameters as:

var x = THREE.Math.mapLinear(-70.16, -150, 150, 0, 1366);

then the value of x is showing 363.51.

Please can anyone explain what exactly happening?

Upvotes: 2

Views: 1002

Answers (1)

James Thorpe
James Thorpe

Reputation: 32212

The mapLinear function takes two ranges of numbers (a1-a2 and b1-b2), and an offset (x):

mapLinear: function ( x, a1, a2, b1, b2 ) {
    return b1 + ( x - a1 ) * ( b2 - b1 ) / ( a2 - a1 );
}

It works out how far through the range of a that x is, and calculates the equivalent position in b and returns it.

With your input, -70.16 is roughly one quarter (23.387%) of the way through the range -150 to 150. The function returns 363.51, which is the equivalent roughly one quarter (23.387%) of the way through the range 0 to 1366.

Upvotes: 6

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