Context3DProfile  - AS3

Use the default feature support profile.

This profile most closely resembles Stage3D support used in previous releases.

Use a constrained feature support profile to target older GPUs

This profile is primarily targeted at devices that only support PS_2.0 level shaders like the Intel GMA 9xx series. In addition, this mode tries to improve memory bandwidth usage by rendering directly into the back buffer. There are several side effects:

• You are limited to 64 ALU and 32 texture instructions per shader.
• Only four texture read instructions per shader.
• No support for predicate register. This affects sln/sge/seq/sne, which you replace with compound mov/cmp instructions, available with ps_2_0.
• The Context3D back buffer must always be within the bounds of the stage.
• Only one instance of a Context3D running in Constrained profile is allowed within a Flash Player instance.
• Standard display list list rendering is driven by Context3D.present() instead of being based on the SWF frame rate. That is, if a Context3D object is active and visible you must call Context3D.present() to render the standard display list.
• Reading back from the back buffer through Context3D.drawToBitmapData() might include parts of the display list content. Alpha information will be lost.