[Documentation] Not clear how to implement scissor command

[EmmanuelMess]

The CLAY_RENDER_COMMAND_TYPE_SCISSOR_START and CLAY_RENDER_COMMAND_TYPE_SCISSOR_END commands are explained as:

Rendering

Enabling scroll for an element will result in two additional render commands:

• commandType = CLAY_RENDER_COMMAND_TYPE_SCISSOR_START, which should create a rectangle mask with its boundingBox and is not subject to culling
• commandType = CLAY_RENDER_COMMAND_TYPE_SCISSOR_END, which disables the previous rectangle mask and is not subject to culling

But I don't understand how to map that to drawing operations. There should be a document that defines what each command means IMO.

[mrneo240]

Think of it as cutting a square out of a piece of paper. You only render things inside the square, not outside.

[EmmanuelMess]

Think of it as cutting a square out of a piece of paper. You only render things inside the square, not outside.

Are the commands nested? Do I need to keep a stack of masks?

[mrneo240]

I have not seen "nesting" but also my examples are trivial. I'm evaluating the current scissor if it's active.

The raylib provided renderer does not handle a stack based approach and due to how Clay orders the commands i would expect it to be fine.

[nicbarker]

Are the commands nested? Do I need to keep a stack of masks?

In the current implementation, yes it is technically possible that these commands will be nested. It's not too common though, so you can probably delay the implementation of it until you see a specific use case.

In future, I will likely build this in as a feature of clay (automatically generate extra scissor start / end commands to "flatten" nested)

[EmmanuelMess]

In the current implementation, yes it is technically possible that these commands will be nested. It's not too common though, so you can probably delay the implementation of it until you see a specific use case.

Apparently I cannot do this under opengl directly, which would mean that extra work would have to be done to be able to actually implement the nesting in opengl renderers.

[mrneo240]

I have multiple opengl and opengl-like renderers and have gone with simple scissoring.

Is there an example layout that produces an incorrect result with doing scissoring this way?