Math for Game Developers

Reusing code with procedures

Procedures are are the simplest black boxes in code. To use a procedure, you just need to know what it does. You don’t need to see what happens inside it until it does something unexpected or wrong. Let’s write a function that doubles a number.

flowchart LR;
    input -->  newLines["`**Procedure**
    Line 1
    Line 2
    Line 3
    ...`"] --> output;

/// Doubles a number and returns
double :: proc(n: int) -> int {
    return 2 * n
}

Comments

Comments are ignored by Odin. They are only for humans to make the code easier to understand.

• Use lines that start with /// above procedures to explain them. These are called doc strings.
• Use // for comments
• Put multiline comments between /* ... */

Input and output types

double :: proc(n: int) -> int

proc(n: int) indicates that that it takes an int (integer) called n and -> int means the proc returns an int. The int type is inbuilt. It can store both negative and positive numbers.

Return statement

return 2*n means the procedure exits with a value of 2 * n for any n passed into it.

Let’s use this proc to print double of 3 and 5.

main :: proc() {
    fmt.println(double(3)) // prints 6
    fmt.println(double(5)) // prints 10
}

We will look at procs and types (like int) in detail in the coming chapters.