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Lua Quick Start Guide

You're reading from   Lua Quick Start Guide The easiest way to learn Lua programming

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Product type Paperback
Published in Jul 2018
Publisher Packt
ISBN-13 9781789343229
Length 202 pages
Edition 1st Edition
Languages
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Author (1):
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Gabor Szauer Gabor Szauer
Author Profile Icon Gabor Szauer
Gabor Szauer
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Toc

Calling C functions from Lua

All of the code that we have written so far has been about exposing C to Lua using Lua Bridge. Any C function exposed through Lua Bridge can be called from Lua. If a function is in a namespace and not a class, it is called with the dot syntax: Math.Sqrt(16). But, if a function is in a class, it needs to be called with the colon syntax: vector:Normalize(). The following code shows how to expose a C function to Lua and how to call it from Lua.

The C code needs to declare the appropriate vector 3 class, a Normalize member function, and a global dot product function. Next, the Register function exposes all of these functions to Lua, using Lua Bridge:

class Vec3 {
public:
float x, y, z;

float Normalize() {
float dot = x * x + y * y + z * z;
if (dot == 0) {
return 0;
}
return sqrt(dot);
}
}

float Dot(Vec3...
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