Question about depth (two objects at the same depth)

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1

I have a very simple project which renders a few triangles on the xy plane.

Some of them overlap and the first drawn always occludes the others. I had added depth testing and tried with .less and .lessequal with no change. I have tried changing the alpha parameter in their colours to 0.5 hoping they would share the overlap, but no change either.

Is there a way to do this?

2

When setting up the depth stencil state, you can do:

func buildDepthStencilState() {
    let depthStencilDescriptor = MTLDepthStencilDescriptor()
    depthStencilDescriptor.depthCompareFunction = .less
    depthStencilDescriptor.isDepthWriteEnabled = false
    depthStencilState = device.makeDepthStencilState(descriptor: depthStencilDescriptor)
}

This will draw the triangles in the order they appear in the vertex buffer.

3

Hello!

Depth testing alone won’t blend overlapping triangles—alpha values only work if blending is enabled. The fix is to turn on blending (glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)) and render transparent objects after opaque ones, ideally sorted back‑to‑front, so overlaps share correctly.