I feel the need to defend OpenGL 
It's not a shortcoming of OpenGL it's a shortcoming of the chosen render technique by the developer. The use technique is fine for solid meshes and performs the fastest for such models. But when you know there is transparency in a model you need to change rendering technique to take care of this. This is the case in any API (also e.g. DirectX )
Like Travis pointed out the 'simplest' way is by sorting the data from back to front so the blending of colors gets done correctly automatically. But this sorting can be costly, there are other solutions floating around on the net including using extra buffers and very complicated shaders. But in the end it's always a quality vs speed thing.
In LDCad I use part level sorting, which is faster then sorting all triangles but less 'nice' in the case of overlapping parts etc. But in the end you barely notice such 'glitches'. Also the used sorting algorithm can be of huge influence depending on the amount of data.
It's not a shortcoming of OpenGL it's a shortcoming of the chosen render technique by the developer. The use technique is fine for solid meshes and performs the fastest for such models. But when you know there is transparency in a model you need to change rendering technique to take care of this. This is the case in any API (also e.g. DirectX )
Like Travis pointed out the 'simplest' way is by sorting the data from back to front so the blending of colors gets done correctly automatically. But this sorting can be costly, there are other solutions floating around on the net including using extra buffers and very complicated shaders. But in the end it's always a quality vs speed thing.
In LDCad I use part level sorting, which is faster then sorting all triangles but less 'nice' in the case of overlapping parts etc. But in the end you barely notice such 'glitches'. Also the used sorting algorithm can be of huge influence depending on the amount of data.