Expression Operator

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January 2024

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DmeExpressionOperator is a DmeOperator that writes to its "value" float attribute the evaluated expression stored in its "expr" string attribute. The expression can read other float attributes on the DmeExpressionOperator, and can nest arbitrarily deep. For example, the expression "clamp(distance * cos(angle), 0, 10)" will cause the DmeExpressionOperator to write a value between 0 and 10 into its "value" attribute, depending upon the value of its "distance" and "angle" float attributes.

Operator Precedence

• unary operators: + - ! func var
• * / %
• + -
• < > <= >=
• == !=
• &&
• ||
•  ?:

Functions

dtor(d) 

converts degrees to radians

rtod(r) 

converts radians to degrees

abs(a)  

absolute value

floor(a)  

rounds down to the nearest integer

ceiling(a) 

rounds up to the nearest integer

round(a)  

rounds to the nearest integer

sgn(a)  

if a < 0 returns -1 else 1

sqr(a)  

returns a * a

sqrt(a)  

returns sqrt(a)

sin(a)  

sin(a), a is in degrees

asin(a)  

asin(a) returns degrees

cos(a)  

cos(a), a is in degrees

acos(a)  

acos(a) returns degrees

tan(a)  

tan(a), a is in degrees

exp(a)  

returns the exponential function of a

log(a)  

returns the natural logarithm of a

min(a,b)  

if a < b returns a else b

max(a,b)  

if a > b returns a else b

atan2(a,b) 

atan(a/b) returns radians (it's Arg(b+ia) actually)

pow(a,b) 

function returns a raised to the power of b

inrange(x,a,b) 

if x is between a and b, returns 1 else returns 0

clamp(x,a,b)  

if x < a returns a else if x > b returns b else returns x

ramp(value,a,b)  

returns 0 -> 1 as value goes from a to b

lerp(factor,a,b)  

returns a -> b as factor goes from 0 to 1

cramp(value,a,b)  

clamp(ramp(value,a,b),0,1)

clerp(factor,a,b)  

clamp(lerp(factor,a,b),a,b)

elerp(x,a,b)  

ramp( 3*x*x - 2*x*x*x, a, b)

noise(a,b,c) 

{ solid noise pattern (improved perlin noise) indexed with three numbers }

rescale (X,Xa,Xb,Ya,Yb) 

lerp(ramp(X,Xa,Xb),Ya,Yb)

crescale(X,Xa,Xb,Ya,Yb) 

clamp(rescale(X,Xa,Xb,Ya,Yb),Ya,Yb)

• Note : arithmetic priorites may not work as intended (for instance, 0-0+3 = -3), so adding brackets might be needed.