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[SOLVED]transparent texture in Entities without ruining water render


WeAthFolD

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I've been recently working on some special effects in my mod, so I started using transparent PNG textures in my entity rendering. But I noticed one(Rather annoying) flaw:

When the back of the entity are plain blocks, the rendering is perfectly OK. However, if the back of the entity are some water blocks, then part of water(To be exact, part which the texture's pixels are really drawn) are not being renderered at all, so I'm blending with whatever block that is beneath the water.

When testing with blended TileEntities, same error occurs.

I also noticed that the GL_ALPHA_TEST switch is enabled and some low-alpha pixels are being filtered. When I turn that switch off, the whole picture area I'm rendering ruins the water rendering.

With multiple entities in the world, sometimes the same problem occurs. It seems that the problem is highly dependent on the drawing order.

So, how can I fix that? Or it is a fixed problem of the MC render engine and we have to just stand it?(If it's the latter one I'll be really sad :()

BTW, all I did in my EntityRender class is equivalent to the following:

@Override
public void doRender(Entity ent, double x, double y, double z, float wtf, float isthis) {
GL11.glEnable(GL11.GL_BLEND);
GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
GL11.glPushMatrix(); {
GL11.glTranslated(x, y, z);
//bind the texture
//render the model or whatever by calling tessellator
} GL11.glPopMatrix();
GL11.glDisable(GL11.GL_BLEND);
}

 

221759opm0k0j4kmddtxt7.jpg

A screenshot(When disabled GL_ALPHA_TEST)

The MC version is 172 and Forge version is 172 recommended.

 

Thanks for your time reading and answering!

 

EDIT: After looking up some informations, I found that this problem is hardly solveable because of limits on OpenGL rendering pipeline. Depth test is done regardless of pixel transparency, and alpha blending is done in later stages. To make it right you have to either not write Z value of current drawing (Which may cause this draw call to be improperly covered), or make depth sorting for all of the transparent stuff within the render scene(Which for current MC rendering routine, impossible). So currently maybe we can just stand this design flaw and use original alpha tests?

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A soft sell for mcbbs and 360, well done.

There are two pass in the rendering process of Minecraft. The first pass is used to render all non-transparent block, most entities and tileentity (in fact, all vanilla ents & tiles), and the second one is used to render transparent block, such as water.

Although I think that it is possible to play some "Z buffer tricks" to avoid this problem, you can just simply let your ents & tiles be rendered in the second pass. Just override the shouldRenderInPass method in your ent/tile class (not the renderer class. Don't confuse shouldRenderInPass and shouldRenderPass of RendererEntityLiving).

However, I'm not sure will it solve this problem. I can't reproduce it...

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You have to make sure your object is rendered after the water, if your object is closer than the water.  For water that works fine, but if you (say) look through ice at your object, it will look mighty strange.  Likewise if you look through one of your objects to see a second one of your objects

 

I don't think in 1.7.10 that this can be properly solved without a big effort.  In 1.8, transparent blocks are depth-sorted so it should work better!

 

-TGG

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