Can somebody give a demo example about how to use STB's rect pack?

[Hubert-Yang]

Question

Hi,

I try to understand how to user stb's STBRectPack, does it working, here I add a unit test like:

STBRPNode.Buffer nodes_buffer = STBRPNode.malloc(3);

STBRPRect.Buffer rect_buffer = STBRPRect.malloc(3);

int index = 0;
for(STBRPRect rect : rect_buffer)
{
rect.set(index++, 0, 0, 30, 40, false);
}

atlas.setup_atlas_map(nodes_buffer, rect_buffer);

public void setup_atlas_map(STBRPNode.Buffer buffers, STBRPRect.Buffer rects)
{

STBRPContext pc =  STBRPContext.malloc(); 
if(pc != null)
{
	STBRectPack.stbrp_init_target(pc, atlas_w, atlas_h, buffers);	
	STBRectPack.stbrp_setup_heuristic(pc, STBRectPack.STBRP_HEURISTIC_Skyline_BF_sortHeight); 
	STBRectPack.stbrp_setup_allow_out_of_mem(pc, true);			
					
	STBRectPack.stbrp_pack_rects(pc, rects); 
}
	
// first we get altas with uv. 

	
for(STBRPNode node : buffers)
{
	System.out.println("get nodes as " + node.x() + " " + node.Y); 
}

}

but seems the node result is nothing. any where is wrong?

Thanks

Hubert Yang

[knokko]

It sounds like a good idea to create a proper sample that demonstrates how to use STB rect pack. I might make one when I have considerably more time.

In the meantime, I do have some old code that uses STB rect pack, which you can use as reference: https://github.com/knokko/gui-stuff/blob/46f178278ba5f83c3af8c6e129fd8a092de276c6/graviks2d/src/main/kotlin/graviks2d/resource/text/TextShapeCache.kt#L68

Unfortunately, I haven't used it in a while, and I don't see any obvious mistakes in your code. Maybe try to print index after this code?

int index = 0;
for(STBRPRect rect : rect_buffer)
{
rect.set(index++, 0, 0, 30, 40, false);
}

and double-check the position() and limit() of rect_buffer! It would not be the first case where the position/limit screws someone over.