ISBRH Alpha Blending Inconsistencies

[Reika]

I am having a problem with my ISBRH (ISimpleBlockRenderingHandler) pipe renders, in that the alpha of the liquid inside visibly flickers between two values as the camera moves, leading to a very broken appearance.

The liquid renders on pass 1, while the body of the pipe (which is rendering fine) renders on pass 0.

 

I have checked for things like multiple calls, lighting, blend mode, and everything else I can think of, and nothing has worked.

I used to have the Tessellator "reboot" with a .draw() and .startDrawingQuads() before doing my rendering (and doing it again after), and did not experience the issue. As of 1.7, however, the rewrites to the tessellator mean that such an approach immediately crashes:

 

 

java.lang.IllegalArgumentException
at java.util.PriorityQueue.<init>(Unknown Source)
at net.minecraft.client.renderer.Tessellator.getVertexState(Tessellator.java:203)
at net.minecraft.client.renderer.WorldRenderer.postRenderBlocks(WorldRenderer.java:274)
at net.minecraft.client.renderer.WorldRenderer.updateRenderer(WorldRenderer.java:230)
at net.minecraft.client.renderer.RenderGlobal.updateRenderers(RenderGlobal.java:1624)
at net.minecraft.client.renderer.EntityRenderer.renderWorld(EntityRenderer.java:1271)

 

 

 

Removing the .draw() and .startDrawing() calls fixes the crash, but introduces the alpha problems. Any ideas?

 

My code:

@Override
public boolean renderWorldBlock(IBlockAccess world, int x, int y, int z, Block block, int modelId, RenderBlocks renderer) {
	RenderableDuct tile = (RenderableDuct)world.getTileEntity(x, y, z);
	for (int i = 0; i < 6; i++) {
		if (renderPass == 0)
			this.renderFace(tile, world, x, y, z, dirs[i]);
		else {
			//Icon ico = tile.getOverlayIcon();
			//if (ico != null)
			//this.renderOverlay(tile, world, x, y, z, dirs[i], ico);
			if (tile.isFluidPipe()) {
				this.renderLiquid(tile, x, y, z, dirs[i]);
			}
		}
	}
	return true;
}

private void renderLiquid(RenderableDuct tile, int x, int y, int z, ForgeDirection dir) {
	Fluid f = tile.getFluidType();
	if (f == null)
		return;
	Tessellator v5 = Tessellator.instance;
	//v5.draw();

	float size = 0.75F/2F;
	float window = 0.5F/2F;
	float dl = size-window;
	float dd = 0.5F-size;
	double in = 0.5+size-0.01;
	double in2 = 0.5-size+0.01;
	double dd2 = in-in2;

	IIcon ico = f.getIcon();
	float u = ico.getMinU();
	float v = ico.getMinV();
	float u2 = ico.getMaxU();
	float v2 = ico.getMaxV();
	double du = dd2*(u2-u)/4D;

	GL11.glColor4f(1, 1, 1, 1);
	GL11.glEnable(GL11.GL_BLEND);
	GL11.glEnable(GL11.GL_CULL_FACE);
	GL11.glEnable(GL12.GL_RESCALE_NORMAL);
	//v5.startDrawingQuads();
	v5.addTranslation(x, y, z);
	int mix = tile.getPipeBlockType().getMixedBrightnessForBlock(Minecraft.getMinecraft().theWorld, x, y, z);
	ReikaLiquidRenderer.bindFluidTexture(f);
	v5.setColorOpaque(255, 255, 255);
	if (f.getLuminosity() > 0) {
		v5.setBrightness(240);
		//ReikaRenderHelper.disableLighting();
	}
	else {
		v5.setBrightness(mix);
	}

	v5.setNormal(dir.offsetX, -dir.offsetY, -dir.offsetZ);

--- lots of .addVertexWithUV ---

	v5.addTranslation(-x, -y, -z);
	//v5.draw();
	GL11.glDisable(GL11.GL_CULL_FACE);
	//v5.startDrawingQuads();

	//GL11.glEnable(GL11.GL_BLEND);
	//GL11.glEnable(GL12.GL_RESCALE_NORMAL);

 

 

Sample images:

[jabelar]

You should contact TheGreyGhost.  He's helped some others with rendering problems.  He has a utility as well that will dump all the G11 state so you can find anything that might not be set as expected.

[Reika]

You should contact TheGreyGhost.  He's helped some others with rendering problems.  He has a utility as well that will dump all the G11 state so you can find anything that might not be set as expected.

How do I contact them?

[Abastro]

I faced the similar problem with rendering my items, and I fixed it by using:

 

GL11.glEnable(GL11.GL_BLEND);

GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);

 

So, maybe have something to do with Blending Function?

 

[TheGreyGhost]

Hi

 

I haven't encountered the Tessellator stop-start problem yet, haven't tried it on 1.7.10 yet.  I would be surprised if there weren't a way around it (even though I don't know what it is )

 

The utility jabelar mentioned is

https://github.com/TheGreyGhost/SpeedyTools/blob/Working/src/speedytools/common/Utilities/OpenGLdebugging.java

 

I've used it in the past to check what the OpenGL settings are; it's not complete, but dumpAllIsEnabled() works and has showed up problems for me before- dump for a good render, dump for a bad render, and spot the difference.  Not sure it is likely to help you in this case, but it might be worth a go.

 

A general comment about alpha blending is that the order of rendering the faces is very important.  If you render the rear pane alpha first, then the front pane alpha next, it will look different to rendering the front pane alpha first and the back pane alpha second.  This is because of the effects of depth testing, and additionally the way alpha blending calculates the final colour.  You could try rendering just one pane and see if the problem persists.

 

Apart from that nothing is springing to mind unless you're doing something accidental like rendering the same pane twice directly on top of itself.

 

-TGG

 

 

 

 

 

 

 

[Reika]

Hi

 

I haven't encountered the Tessellator stop-start problem yet, haven't tried it on 1.7.10 yet.  I would be surprised if there weren't a way around it (even though I don't know what it is )

 

The utility jabelar mentioned is

https://github.com/TheGreyGhost/SpeedyTools/blob/Working/src/speedytools/common/Utilities/OpenGLdebugging.java

 

I've used it in the past to check what the OpenGL settings are; it's not complete, but dumpAllIsEnabled() works and has showed up problems for me before- dump for a good render, dump for a bad render, and spot the difference.  Not sure it is likely to help you in this case, but it might be worth a go.

 

A general comment about alpha blending is that the order of rendering the faces is very important.  If you render the rear pane alpha first, then the front pane alpha next, it will look different to rendering the front pane alpha first and the back pane alpha second.  This is because of the effects of depth testing, and additionally the way alpha blending calculates the final colour.  You could try rendering just one pane and see if the problem persists.

 

Apart from that nothing is springing to mind unless you're doing something accidental like rendering the same pane twice directly on top of itself.

 

-TGG

I faced the similar problem with rendering my items, and I fixed it by using:

 

GL11.glEnable(GL11.GL_BLEND);

GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);

 

So, maybe have something to do with Blending Function?

As is stated in the first post, I have already checked for these. Blending is enabled and in default blend (alpha-on-background) mode. Nothing is being rendered twice per call. Positions are unchanged from code which has worked since 1.2.5.

 

Also, your link is broken.

 

EDIT:

Oh, this is just perfect. Now I get that TessellatorVertexState crash even when not rebooting the tessellator. No, I have not changed the code since making my first post, and until five minutes ago, it was working, because that pipe block is still in the world and always has been.

EDIT 2:

It even crashes no matter what, with no code running, as long as renderWorldBlock returns true (which if false prevents any rendering from even being done)!

[Reika]

OK, an update:

I have found a hacky-though-harmless fix for the crash. Simply dump in four "scrap" vertices (I do it at 0,0,0) and then the TesselatorState creation will not crash. It also allowed me to run my normal tessellator reboot code, which allowed me to discover something:

 

When the reboot code is not active, the behavior described in my original post is observed. Turn the reboot code on, and then the flickering is between the correct alpha value and complete transparency.

 

This is a strong indicator of something running twice, or of some alpha threshold application, but I can again confirm that the code and vertices are NOT being called more than once per render cycle.

 

Also, the "flicker" is in fact as follows:

While the player is accelerating (velocity is changing in magnitude or direction), the "low alpha" state is rendered. When the player is standing still, or moving at a constant velocity, the "high alpha" state is rendered.

What the hell is going on here?

[TheGreyGhost]

Hi

 

Well that's confusing.  I'm out of ideas.

 

This link should work for that utility if you are still keen to try it.

https://github.com/TheGreyGhost/SpeedyTools/blob/master/src/speedytools/common/utilities/OpenGLdebugging.java

 

-TGG

[Reika]

Hi

 

Well that's confusing.  I'm out of ideas.

 

This link should work for that utility if you are still keen to try it.

https://github.com/TheGreyGhost/SpeedyTools/blob/master/src/speedytools/common/utilities/OpenGLdebugging.java

 

-TGG

The link works now, but I kind of need to fix my pipe renders. Does anyone else commonly use ISBRHs?