CL_PixelBuffer drawing

[intser]

Hello.

I attempt draw tile map based on some graphical data from wrl file. I extract tiles 64x64 and store in CL_PixelBuffers. Next I calculate tiles count on screen and draw using CL_GraphicContext::draw_pixels.
But I have strange behavior when I need draw small part of pixel buffer. For example I have screen height 480 and current vertical position = 438, I need draw only half tile:
CL_PixelBuffer pb = wr.getMapBuffer(1,1); // get 64x64 pixel buffer
gc.draw_pixels(100,gc.get_height() - 32, pb, CL_Rect(0,0,64,32)); // draw only 32 pixels from top of tile
it doesn't work - nothing happened.
But if I create new pixel buffer with size 64x32 it works:
CL_PixelBuffer pbTarget(64,32,CL_TextureFormat::cl_rgb8);
pb.convert(pbTarget, CL_Rect(0,0,64,32), CL_Rect(0,0,64,32));
gc.draw_pixels(100,gc.get_height() - 32,pbTarget, CL_Rect(0,0, 64, 32));
What I'm doing wrong? I don't want create special target buffer each time when I need draw tile near screen border.

[rombust]

Assuming you are using OpenGL (clanGL or clanGL1)

Avoid using gc.draw_pixels(), it only exists for clanSWRender. It's very slow on OpenGL

Method 1)
CL_Image image(gc, pixelbuffer, pixelbuffer.get_size());
image.draw(gc, xpos, ypos);
(remember to only calculate image once in the program, opengl upload is slow)

Method 2) (Advanced - Takes advantage of batch drawing, since all images are part of the same texture)
CL_TextureGroup texture_group(1024, 1024);
std::vector<CL_Image> images;
... For each pixelbuffer
CL_Subtexture subtexture = texture_group.add(gc, CL_Size(32, 32);
subtexture.get_texture().set_subimage( subtexture.get_geometry().get_top_left(), pixelbuffer, pixelbuffer.get_size() );
images.push_back(CL_Image(gc, subtexture));
...
image[offset].draw(gc, xpos, ypos);

[intser]

Thanks,

Where I can get more info about CL_TextureGroup?

[rombust]

There is a tiny bit in
http://clanlib.org/wiki/MainDocs:Raster_Graphics

else, just the api

http://clanlib.org/docs/clanlib-2.3/...tureGroup.html

[sphair]

Something like this might work as well:

// in loading
CL_SpriteDescription desc;
foreach pixelbuffer you've extracted
     desc.add_frame(pixelbuffer);
CL_Sprite sprite(gc, desc);

// in main loop
sprite.set_frame(tile_index),
sprite.draw(gc, xpos, ypos);

Don't worry about drawing outside screen, it clips.

[rombust]

Sphair's method is much much better.

Also, if you scale the tiles and get artifacts:
pixelbuffer = CL_PixelBufferHelp::add_border(pixelbuffer, 1, pixelbuffer.get_size());
can be used to stop colour bleeding at the edge problems.

[intser]

Thanks a lot.

sphair,
your solution is very good. I have to implemented it.

I realized CL_TextureGroup is simple container for CL_Texture objects. When I create texture group I set initial texture size and if I attempt to store subtexture larger than initial size it will increasing.
All subtextures store in binary tree and contain reference to parent texture and own rect in this texture. It's correct?
I have to understand CL_TextureGroup is obsolete object? - because CL_Sprite I think much simplier.

[rombust]

CL_Sprite uses CL_TextureGroup inside "CL_Sprite_Impl::create_textures"

CL_TextureGroup is probably for advanced users. .. so you can have CL_Image's and CL_Font glyphs in same CL_Texture

[sphair]

Texturegroup is a class that packs small textures together efficiently. It is, as rombust says, a class for a very specific, advanced use.