g2D - Geometry art built coding

Use the code basics like loops, control flow and specialized functions to generate your geometry artworks.

Examples of g2D Geometry Art

• source code in _examples folder

   

   

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Installation

Go get

$ go get -u github.com/lucasepe/g2d

Ready-To-Use Releases

Here you can find g2d already compiled for:

• MacOS
• Linux
• Windows

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How to use

To execute a local g2d script:

$ g2d /path/to/my-script.g2d

To execute a g2d script stored somewhere on the web:

$ g2d http://my-cool-site.com/remote/path/to/my-script.g2d

Use the --directory (or the shorter -d) flag to specify a destination folder for the generated PNG images.

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The g2D Programming Language Syntax

Example-programs can be found beneath examples/ which demonstrate these things, as well as parts of the standard-library.

Types

g2D has the following data types: bool, int, float, str, array, and fn.

Type | Syntax | Notes | --------- | ----------------------------------------- | ----------------------------------------------- | bool | true false | | int | 0 42 1234 -5 | is a signed 64-bit integer | float | 0.5 4.2 1.234 -5.5 | is a 64-bit double-precision floating point | str | "" "foo" "\"quotes\" and a\nline break" | are immutable arrays of bytes | array | [] [1, 2] [1, 2, 3] | grow-able arrays (use the append() builtin) | fn | fn(a, b) { ... } | defines a custom function |

Bindings

Variables are bounded using the := operator.

a := 3
b := 1.2

Variables may be integers, floats, strings, or arrays/hashes.

To update a variable you can simply specify the equals = operator:

a := 3    // Binding
a = a + 5 // Updating

Arithmetic operations

g2D supports all the basic arithmetic operation of int and float types.

a := 5
b := 3

c := a + b
d := c / 2
e := d * d

Builtin containers

g2d has one builtin containers: array.

Arrays

An array is a list which organizes items by linear sequence. Arrays can hold multiple types.

a := [1, 2.3, "hello!"]
b := [false, true, "Hello World", 3, 3.13]

Adding to an array is done via the push builtin function:

a = append(a, "another")

You can iterate over the contents of an array like so:

i := 0
while( i < len(a) ) {
    print( "Array index ", i, " contains ", a[i], "\n")
    i = i + 1
}

With the definition we included that produces this output:

Array index 0 contains 1
Array index 1 contains 2.3
Array index 2 contains hello!
Array index 3 contains another

Functions

g2D uses fn to define a function which will be assigned to a variable for naming/invocation purposes:

sum := fn(a, b) { return a + b }

print(sum(5,3), "\n")       // Outputs: 8
print(sum(2.5,7.5), "\n")   // Outputs: 10

Functions can be passed as values to others functions:

addTwo := fn(a, b, f) { 
    return 2 + f(a, b) 
}

tot := addTwo(68, 1, sum)
print(tot, "\n")            // Outputs: 71

Functions inside functions

multiplier := fn(q) {
    return fn(x) {
        return x*q
    }
}

multThree := multiplier(3)

print(multThree(2), "\n")  // Outputs: 6
print(multThree(3), "\n")  // Outputs: 9
print(multThree(4), "\n")  // Outputs: 12

If-else statements

g2D supports if-else statements.

max := fn(a, b) {
    if (a > b) {
        return a;
    } else {
        return b;
    }
}

print( max(1, 2) )  // Outputs: 2

Switch Statements

g2D supports the switch and case expressions:

switch n := randi(10) {
    case n % 2 == 0 {
        print(n, " is even", "\n")
    }
    default {
        print(n, " is odd", "\n")
    }
}

While Loops

g2D supports only one looping construct, the while loop:

i := 30
while (i > 0) {
    print(i, " ")
    i = i - 10
}
// 30 20 10

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Builtin functions

Core

Function | Description ---------------------- | -------------------------------------------------------------------------- | exit([status]) | exits the program immediately with the optional status or 0 | input([prompt] | reads a line from standard input optionally printing the specified prompt | print(...) | output a string to stdout | printf(pattern, ...) | output a string to stdout (formatted according the specified pattern) | sprintf(pattern, ...)| like printf(...) but returns a string | bool(val) | converts value to a bool | float(val) | converts decimal value str to float - if val is invalid returns null | int(val) | converts decimal value str to int - if val is invalid returns null | str(val) | returns the string representation of val | len(iterable) | returns the length of the iterable (string or array) | append(array, val) | returns a new array with value pushed onto the end of array |

Calculation

Function | Description ----------------------- | -------------------------------------------------------------------------- | abs(x) | returns the absolute value of x | atan(x) | returns the arc tangent, in radians, of x | atan2(x, y) | returns the arc tangent of y/x | cos(x) | returns the cosine of the radian argument x | degrees(angle) | converts radians into degrees | hypot(p, q) | returns sqrt(p*p + q*q) | lerp(start, stop, amt)| calculates a number between two numbers at a specific increment | map(v, b1, e1, b2, e2)| re-maps a number from one range to another | max(v1....vn) | returns the largest value in a sequence of numbers | min(v1....vn) | returns the smallest value in a sequence of numbers | pow(x, y) | returns x**y, the base x exponential of y | sin(x) | returns the sine of the radian argument x | sqrt(x) | returns the square root of x | radians(angle) | converts a degree measurement to its corresponding value in radians | randf([min], [max]) | returns a random float between min and max - by default min=0.0 and max=1.0| randi([min], [max]) | returns a random int between min and max |

Basic graphic functions

Function | Description ------------------------------------- | ------------------------------------------------------------------------------------- | size(w,[h]) | sets the size of the drawing; when both w and h are specified creates a rectangular image otherwise creates a squared one | viewport(xMin, xMax, yMin, yMax, xOffset, yOffset) | sets up user-defined coordinate system; performs a screen reset (drawings are cleared)| clear() | fills the entire image with the current color; clear all drawings | fillColor(hexcolor) | sets the fill color to the specified hexcolor; example fillColor("#ff0000") | fillColor(r, g, b, [a]) | sets the fill color to r,g,b,a values - should be between 0 and 255, inclusive | strokeColor(hexcolor) | sets the stroke color to the specified hexcolor; example strokeColor("#ff0000") | strokeColor(r, g, b, [a]) | sets the stroke color to r,g,b,a values - should be between 0 and 255, inclusive | strokeWeight(weight) | sets the stroke thickness to the specified width | dashes([s1, s2, ...sn]) | sets the current dash pattern to use (call with zero arguments to disable dashes) | stroke() | strokes the current path with the current stroek color and line width the path is cleared after this operation | fill() | fills the current path with the current fill color; open subpaths are implicity closed.<br/> The path is cleared after this operation | fillAndStroke() | fills the current path with the current fill color and strokes it with the current stroke color; the path is cleared after this operation | push() | saves the curren