pipmak-users

Impossible call 'patch' inside onkeydown handler?

[Andrea V. <and...@gm...>]

Hello!

I got a strange behavior with build 179 and this simple code:
--------------------------------------------------------------
cubic {
	"skyFront.jpg", --front
	"skyRight.jpg", --right
	"skyBack.jpg",  --back
	"skyLeft.jpg",  --left
	"skyTop.jpg",   --top
	"skyBottom.jpg" --bottom
}


onkeydown (
    function(key)
      p_ref=patch{nx=1,ny=1,nz=0,nw=1,nh=1,angley=90,image="left.png"}  
      return false
   end
   )
--------------------------------------------------------------

When you press a key, you will get the message:

    Error running local keydown handler:
    1/node.lua:13: attempt to call global 'patch' (a nil value)

if I substitute patch with pipmak_internal.patch, it seems to work fine,
for this simple example,
but using a more complex code, Pipmak crash in that point...

With the debug I have seen that the error occur in images.c
----------------------------------------------------------------------
void releaseImageFromGL(Image *img) {
	img->texrefcount--;    /// <--error occur in this point
	if (img->texrefcount <= 0) {
		glDeleteTextures(1, &(img->textureID));
		img->textureID = 0;
	}
----------------------------------------------------------------------

What do you thinking about?
Is it a problem of my build, or really I cannot define a new patch inside
a keydown handler?

Bye.
Andrea

Re: Impossible call 'patch' inside onkeydown handler?

[Christian W. <cwa...@gm...>]

Andrea Viarengo wrote:
> onkeydown (
>     function(key)
>       p_ref=patch{nx=1,ny=1,nz=0,nw=1,nh=1,angley=90,image="left.png"}  
>       return false
>    end
>    )
> --------------------------------------------------------------
> 
> When you press a key, you will get the message:
> 
>     Error running local keydown handler:
>     1/node.lua:13: attempt to call global 'patch' (a nil value)

This is by design. "patch" is only available at node loading time, not 
as a run-time function. You should not think of it as a function (even 
though it technically is one), but as part of a declarative node 
description syntax.

> if I substitute patch with pipmak_internal.patch, it seems to work fine,
> for this simple example,
> but using a more complex code, Pipmak crash in that point...

You're not supposed to use pipmak_internal. It's called internal for a 
reason...

We should probably make sure that you can't crash Pipmak even if you do, 
but that looks quite tedious... :/

> Is it a problem of my build, or really I cannot define a new patch inside
> a keydown handler?

You can't create patches at run time. What would you need that for? 
Would it be very inconvenient to have to reload the node for it?

  -Christian

Re: Impossible call 'patch' inside onkeydown handler?

[Andrea V. <and...@gm...>]

Christian Walther <cwalther <at> gmx.ch> writes:

> You can't create patches at run time. What would you need that for? 
> Would it be very inconvenient to have to reload the node for it?

Ok, I understand you, I should find a workaround to this.

Well, I'm working on a lua library fot drawing simple 3d object,
as explain you before, the big problem is put the patches in the
correct geometrical order, 
So, for the moment I have operate in this manner:

I calculate all the parameters to drawing patches of my 3d object
(nx,ny,...angley...image...)
and put inside a table.

During this phase I eliminate backfaces to reduce total number of patches.

I reorder the table of the patches from farest to nearest

I cycle along the table and draw the patch, 
To do this, I use another table to store patch id, 
I reuse patches stored in this table that are always ordered from back to
front. If I found a patch in this table, I use it, otherwise I create a
new one and I append it to the table for future use.
Because the backface removal, the number of patches that I see can vary
depending on the angle of view.

So if I want to schedulate the rotation of my object, it's possible which,
for some angle of view, I need extra patches...

Now I have to predetermine the maximum number of patches and allocate
all patches before runtime.

If I eliminate backfaces removal, the problem never occur, because the 
number of the faces is always the same.

I have tryed (just for test) to enable depth buffer on SDL (before calling 
SDL_SetVideoMode( width, height, bpp, flags )

using:

SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );

but it's not sufficient, because the behaviour isn't changed.....

Bye

Andrea
 

Re: Impossible call 'patch' inside onkeydown handler?

[Christian W. <cwa...@gm...>]

Andrea Viaengo wrote:
> Christian Walther <cwalther <at> gmx.ch> writes:
> 
>> You can't create patches at run time. What would you need that for? 
>> Would it be very inconvenient to have to reload the node for it?
> 
> Ok, I understand you, I should find a workaround to this.
> 
> Well, I'm working on a lua library fot drawing simple 3d object,
> as explain you before, the big problem is put the patches in the
> correct geometrical order, 
> So, for the moment I have operate in this manner:
> ...

OK... I hope you understand that you are operating so far outside of 
Pipmak's primary scope here that I treat the particular problems you're 
encountering with low priority.

> I have tryed (just for test) to enable depth buffer on SDL (before calling 
> SDL_SetVideoMode( width, height, bpp, flags )
> 
> using:
> 
> SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );
> 
> but it's not sufficient, because the behaviour isn't changed.....

You need to glEnable(GL_DEPTH_TEST), too. But as I mentioned, I suspect 
that having the depth test enabled all the time will mess up (i.e. make 
invisible) a lot of things. glDepthFunc(GL_LEQUAL) may help somewhat in 
that case.

  -Christian