Re: How to access following data using Luabind

make sure your created and made your GL context current when you call any GL function, otherwise you'll most probably crash immediately.



________________________________
Von: Nicolas Goles <[email protected]>
An: [email protected]
Gesendet: Sonntag, den 20. Juni 2010, 3:07:38 Uhr
Betreff: Re: [luabind] How to access following data using Luabind

Hello, 

Thanks for your help.

I was able to make it work, though I have 1 problem:

This is my Placemark (trapezoid) C++ Class constructor:

Placemark::Placemark(floatx1, floaty1,
     float x2, float y2,
     float x3, float y3,
     float x4, float y4)
{ 
vertex[0] = Vec2f(x1, y1);
vertex[1] = Vec2f(x2, y2);
vertex[2] = Vec2f(x3, y3);
vertex[3] = Vec2f(x4, y4);

//Create the vertex Dots
for(int i = 0; i < 4; ++i)
{
VertexCircle*c= newVertexCircle(vertex[i], i);
c->setParent(this);
vertexDots.push_back(c);
}

glGenBuffers(1, &vbo);
}

However I bounded this constructor using luabind and called it in Lua with:

p = Placemark(1.0, 2.0, 3.0, 4.0, 1.0, 2.0, 3.0, 4.0)

The following piece of code in my C++ constructor:

glGenBuffers(1, &vbo); //vbo is a Placemark private attribute. GLuint vbo;

Makes my Application to Crash.

I don't really know why, and it's easy to take that line out from my constructor, but still I was wondering if someone could enlighten me about why is it crashing when calling the OpenGL function glGenBuffers ??

Thanks.

--------------------------------------------------------------
Nicolas Goles Domic
Founder & Lead Programmer of Gando Games





On Jun 18, 2010, at 4:42 AM, Iliya Trendafilov wrote:

Hi,
>
>Just to access the data from your script in C++ you can do something like this:
>
>luabind::object_cast<double>(luabind::globals(lua)["polygons"]["vertex"][1][1])
>// returns x1 of the first trapezoid
>
>The return of every operator[] above is luabind::object that you could "cache".
>
>That said, I'd rather register Color3f and Trapezoid classes with at
>least their constructors, then write a tiny glue lua script
>
>polygonInsances = {}
>for i = 1, #polygons.vertex
>do
>   local v = polygons.vertex[i]
>   local c = polygons.color[i]
>   polygonInstances[i] = Trapezoid(v[1][1], v[1][2], v[2][1],
>v[2][2], v[3][1], v[3][2], v[4][1], v[4][2], Color3f(c[1], c[2],
>c[3]))
>done
>
>And then use polygonInstances:
>
>luabind::object_cast<Trapezoid>(luabind::globals(lua)["polygonInstances"][1]);
>// returns the first trapezoid
>
>Hope that helps.
>(WARNING: None of the code above has been compiled or run through Lua
>interpreter)
>
>
>
>On Fri, Jun 18, 2010 at 8:54 AM, Nicolas Goles <[email protected]> wrote:
>
>Hello,
>>
>I'm quite new to Luabind, I'm trying to access the following data
>>
>polygons = {
>>
>-- 3 "different" Trapezoidal polygons, 4 vertex (x,y) each.
>>
>vertex = {
>>
>{{1,0}, {1,10}, {21,30}, {25,35}},
>>
>{{1,0}, {1,10}, {21,30}, {25,35}},
>>
>{{1,0}, {1,10}, {21,30}, {25,35}},
>>
>},
>>
>-- 3 Colors ( R , G , B) one for each polygon
>>
>color = {
>>
>{1,0,0},
>>
>{0,1,0},
>>
>{0,0,1},
>>
>}
>>
>}
>>
>it represents 3 "different" trapezoidal polygons, each one with a color.
>>
>In my Application, I have a C++ class "Trapezoid" that has a constructor
>>
>that receives 8 floats (x1,y2 , x2, y2.... ) and a color.
>>
>Trapezoid::Trapezoid(x1, y1, x2, y2, x3, y3, x4, y4, Color3f color);
>>
>What would be the correct way to access this Lua script using luabind? I
>>
>have been struggling all day.
>>
>Sorry if this is noobish, but haven't found any clear solutions for this (
>>
>most of the examples focus on executing functions, and more complex stuff )
>>
>What would you guys suggest  ?
>>
>Thanks!
>>
>_Nicolas
>>
>------------------------------------------------------------------------------
>>
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>>
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>>
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>>
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>>
>
>>
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