Glass that starts out broken

From Valve Developer Community

This tutorial assumes you already know how to create breakable glass. If not, follow that tutorial first.

First method

This method consists on breaking the glass with the help of an explosion that occurs once the map is loaded.

• Make a func_breakable_surf with a frame around it (as if you are making a normal breakable window).
• Set up an env_explosion in the middle of the window, then change the options as follows:

Class: env_explosion
Keyvalues		Comments
Name	<name>	<name> is whatever name you wish to give to this entity
Magnitude	1

• Then in the flags tab, change the flags as follows:

	Flag			Comments
		No fireball
		No smoke
		No decal
		No sparks
		No sound
		No fireball smoke
		No particles
		No Dlights

• Set up a logic_auto near the env_explosion (it doesn't matter where you put it, but I recommend that you put it in a convenient place)
• Change the entity outputs for the logic_auto as follows:

		My output	Target entity	Target input	Parameter	Delay	Only once	Comments
		OnMapSpawn	<name>	Explode			Yes	<name> is the name you gave the entity in the third step above

• Then in the flags tab, change the flags as follows:

	Flag			Comments
		Remove on fire

• Test your map! When it loads the env_explosion will break the glass leaving the jagged glass edges on the side of the frame.

Alternative method

This method consists on setting the logic_auto entity to directly shatter the glass once the map is loaded, which eliminates the need of creating an explosion.

• Name the func_breakable_surf you created in step 2 above.
• Don't create the env_explosion entity in step 3 above.
• Do create the logic_auto entity in step 5 above.
• Change the entity outputs for the logic_auto as follows:

		My output	Target entity	Target input	Parameter	Delay	Only once	Comments
		OnMapSpawn	<name>	Shatter	0.5 0.5 128		Yes	<name> is the name you gave the func_breakable_surf entity

• Adjust the parameter above as desired. Changing the size of the third number (128) will change how much of the window is broken.