gl_InstanceID does not work correctly with Vulkan

gl_InstanceID does not work correctly with Vulkan

Steps to reproduce the bug:

1. Apply the attached resource pack with Vulkan

2. Enable the “Improved transparency” setting

3. Check the water rendering

4. Do the same thing with OpenGL

Expected behavior:

The water should be rendered like OpenGL

Code analysis:

   @Override
   public void draw(final int firstVertex, final int vertexCount) {
      if (this.pipeline != null && this.pipeline.isValid()) {
         this.pushDescriptors();
         VK12.vkCmdDraw(this.secondaryCommandBuffer(), vertexCount, 1, firstVertex, vertexCount);
      }
   }

The Vulkan signature is vkCmdDraw(cmd, vertexCount, instanceCount, firstVertex, firstInstance). The 5th argument firstInstance is set to vertexCount instead of 0.

Consequence: gl_InstanceIndex in any vertex shader will equal vertexCount instead of 0 for non-indexed draw() calls. Any shader that reads gl_InstanceIndex (for instancing, per-instance SSBO lookups, etc.) will have a shifted index.