Transparent shader allows the objects below to sho

问题:

In my scene, the smileys(Quad with png image) are placed at Y:0 and the dots(Quad with tiling 3X3) are placed at Y: -0.25. The shader I need to use for the smileys is Transparent-Diffuse as I am using a circle png image.

But the dots I use below are showing up above the smiley. Using any other shader like Diffuse solves the issue but the smiley becomes a square.

Screenshot:

If you need any more clarifications please dont hesitate to ask.

Edit: I have attached the shader details of both the smiley and the dots from the inspector panel. link: http://postimg.org/image/cvws1os7d/

Edit 2: I have found that the issue should be with the MainCamera and especially with distance & "Field Of View". I need to use "Perspective" as projection type and 140 as Field of View.

If I change the projection type to Orthographic the issue is completely fixed.

The below screenshots show how the distance and Field of View controls the appearance of the dots over the smiley.

Screenshot 1: Y position: 8.48 Field of View: 30 link: http://postimg.org/image/s31tttrkp/

Screenshot 2: Y position: 9.7 Field of View: 30 link: http://postimg.org/image/f71sq0y4b/

Screenshot 3: Y position: 11.41 Field of View: 30 link: http://postimg.org/image/3uk4az3d3/

Screenshot 4: Y position: 1 Field of View: 140 link: http://postimg.org/image/bul9zwg7z/

Can this be a clue?

回答1:

Just a couple of info, on how transparency is typically implemented (not only by Unity).

Meanwhile opaque objects can be drawn in any order (even if sorting them in front-to-back order can eventually improve some GPU performances relying on an early z-cull). Which pixels are visible can be deduced using the depth value stored into the z-buffer.

You can't rely on z-buffer for transparency. For rendering translucent objects a typical approach is to draw them after all opaque objects, and sorting them in back-to-front order (transparent objects more distant from the camera are drawn first).

Now the question is: how do you sort objects? with a perspective camera and meshes of a generic shape, the solution is not obvious.

For quad meshes oriented parallel to a ortographic camera view plane, the z order is implicitly correct (that's why it always works for you). You can also notice that camera position influences the drawing order, because with perspective camera the order is calculated as distance between object position and camera.

So what can you do with Unity3d, in your specific use case scenario? A couple of tricks:

• Explicitly set the render queue of the material
• Explicitly set the render order inside the shader (similar of the above, but equals to every object with the same shader)
• Fake the depth using Offset into the shader (not that useful in your case but worth to be known)

hope this helps

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EDIT

I didn't know that, the camera transparency sorting mode appears to be customizable. So this is another solution, maybe the best for your case if you want to use a perspective camera.

回答2:

If you are using Sprite Renderer component to render the images, you have to change the rendering order with Sorting Layer and Order in Layer parameters instead of changing the Y position.

Sorting layers can be added by clicking the "default" and choosing "Add Sorting Layer..". The order of the layers is changed by dragging them into different order. With Order in Layer lower numbers are rendered first. This means that higher numbers will be drawn on top of lower ones.