Sfml multi-textured tile map

[Inspector Coarse]

How would i do multi texturing in sfml?

Since sf::vertex is set, i would have to use the colour channel to carry the texture weights, and then all i need to do is specify the uv somehow to sample the appropriate texture from the texture 'atlas'.
How would/could i do that?

I don't quite understand "gl_TexCoord[0]" here.

vec4 pixel = texture2D(mapTexture, gl_TexCoord[0].xy);

Any help appreciated.

[eXpl0it3r]

Try to patch as much as possible on one texture without create huge textures that are only supported by the latest high-end GPUs and then use one vertex array per texture.

Not sure what you're trying to ask with the OpenGL code here...

[Inspector Coarse]

So that the overlaying textures blend to produce the multi texture effect ?


I was planning on doing it in the shader, hence that line of code which is from a basic texturing pixel shader.
I just don't know how to go about accessing different parts of the texture(atlas) to draw the right part according to the weight information.

[eXpl0it3r]

Ah I didn't realize you were talking about multi-texturing. I've never done that, so I'm unsure, but I guess you can do all of it in a shader.

[Hapax]

I guess you can do all of it in a shader.

You can pass multiple textures to a shader and use them as you wish, but passing multiple texture-coordinates per vertex (one for each texture) seems impossible (with the current SFML setup).
Sending extra data with vertices would solve that problem. I 'think' I've seen talk of it being considered for SFML but I'm not sure where. It may be for SFML 3 where it'll probably use 'modern' OpenGL.

[Inspector Coarse]

All i need to do is sample the same texture at at-least four different points, so using an offset will do. Using colour channel that gives me 4 different values(uint8 so 0-255) for weights so, four textures.

Tex2pos will be Tex1pos + offset of some kind. etc.


pixel = Tex1Pos * TexWeight.x
pixel += Tex2 Pos * TexWeight.y
...     +=
...     +=


 Is this possible?
 

The tile map will appear smoothly textured as a result, with textures painted according to the weight values which could be a heightmap or any old map.

[Jabberwocky]

Yep, totally possible.
I've done something very similar before with no problem.

I did it with 4 different textures, but there's absolutely no reason you couldn't do it using a texture atlas with 4 different offsets passed in as uniform params.