MultiplyAlphaRenderTypeBuffer.java

package gigaherz.signbutton;

import com.mojang.blaze3d.vertex.IVertexBuilder;
import net.minecraft.client.renderer.IRenderTypeBuffer;
import net.minecraft.client.renderer.RenderType;

public class MultiplyAlphaRenderTypeBuffer implements IRenderTypeBuffer
{
    private final IRenderTypeBuffer inner;
    private final float constantAlpha;

    public MultiplyAlphaRenderTypeBuffer(IRenderTypeBuffer inner, float constantAlpha)
    {
        this.inner = inner;
        this.constantAlpha = constantAlpha;
    }

    @Override
    public IVertexBuilder getBuffer(RenderType type)
    {
        return new MultiplyAlphaVertexBuilder(inner.getBuffer(type), constantAlpha);
    }
}

MultiplyAlphaVertexBuilder.java

package gigaherz.signbutton;

import com.mojang.blaze3d.vertex.IVertexBuilder;
import net.minecraft.client.renderer.Matrix3f;
import net.minecraft.client.renderer.Matrix4f;

public class MultiplyAlphaVertexBuilder implements IVertexBuilder
{
    private final IVertexBuilder inner;
    private final float constantAlpha;

    public MultiplyAlphaVertexBuilder(IVertexBuilder inner, float constantAlpha)
    {
        this.inner = inner;
        this.constantAlpha = constantAlpha;
    }

    @Override
    public IVertexBuilder pos(double x, double y, double z)
    {
        return inner.pos(x,y,z);
    }

    @Override
    public IVertexBuilder pos(Matrix4f matrixIn, float x, float y, float z)
    {
        return inner.pos(matrixIn, x, y, z);
    }

    @Override
    public IVertexBuilder color(int red, int green, int blue, int alpha)
    {
        return inner.color(red,green,blue,(int)(alpha*constantAlpha));
    }

    @Override
    public IVertexBuilder tex(float u, float v)
    {
        return inner.tex(u, v);
    }

    @Override
    public IVertexBuilder overlay(int u, int v)
    {
        return inner.overlay(u, v);
    }

    @Override
    public IVertexBuilder lightmap(int u, int v)
    {
        return inner.lightmap(u, v);
    }

    @Override
    public IVertexBuilder normal(float x, float y, float z)
    {
        return inner.normal(x,y,z);
    }

    @Override
    public IVertexBuilder normal(Matrix3f matrixIn, float x, float y, float z)
    {
        return inner.normal(matrixIn, x, y, z);
    }

    @Override
    public void endVertex()
    {
        inner.endVertex();
    }
}