Call of Duty 4: Portals - Revision history

CoDEmanX at 13:26, 29 July 2009

2009-07-29T13:26:26Z

← Older revision		Revision as of 13:26, 29 July 2009
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	~~[[Category:Call of Duty 4]]~~
	~~[[Category:Modtools]]~~
	~~[[Category:Radiant]]~~
	~~[[Category:Advanced Editing]]~~
	{{warning_radiant}}		{{warning_radiant}}
	[[Image:Uc.gif\|100px\|center]]		[[Image:Uc.gif\|100px\|center]]
	~~[[Image:Nutshell.png]]~~ Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.		{{Note\|Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.}}

	== Quick Intro ==		== Quick Intro ==
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	</pre>		</pre>

			[[Category:Call of Duty 4]]
			[[Category:Modtools]]
			[[Category:Radiant]]
			[[Category:Advanced Editing]]
			[[Category:Portals]]

Zeroy at 20:30, 17 October 2008

2008-10-17T20:30:27Z

← Older revision		Revision as of 20:30, 17 October 2008
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			[[Category:Call of Duty 4]]
			[[Category:Modtools]]
			[[Category:Radiant]]
			[[Category:Advanced Editing]]
	{{warning_radiant}}		{{warning_radiant}}
	[[Image:Uc.gif\|100px\|center]]		[[Image:Uc.gif\|100px\|center]]

Zeroy: /* Quick Intro */

2008-10-17T08:39:59Z

Quick Intro

← Older revision		Revision as of 08:39, 17 October 2008
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	Portals gives better culling than PVS since they effectively do the exact cell-to-cell PVS for a single view point. Portals can even cull geometry when you turn the mouse, rather than being fixed for a given point. Too many portals can slow the game down because it does too much time calculating what to draw. Portals do frustum culling of triangles. Because of this it is not necessary to have portals inside of rooms, only at the windows and doors. Use r_showportals 1 in the game to see where IW placed their portals.		*Portals gives better culling than PVS since they effectively do the exact cell-to-cell PVS for a single view point. Portals can even cull geometry when you turn the mouse, rather than being fixed for a given point. Too many portals can slow the game down because it does too much time calculating what to draw. Portals do frustum culling of triangles. Because of this it is not necessary to have portals inside of rooms, only at the windows and doors. Use r_showportals 1 in the game to see where IW placed their portals.

	Too few portals can slow the game down because it quickly decides to draw too much.		*Too few portals can slow the game down because it quickly decides to draw too much.



	You have to place portals in radiant for portal-based rendering. A portal can be any brush face; it doesn't have to be axial and it doesn't have to be square. To create a portal, create a brush and then make most sides “textures / common / portalnodraw” and one side "textures / common / portal".		*You have to place portals in radiant for portal-based rendering. A portal can be any brush face; it doesn't have to be axial and it doesn't have to be square. To create a portal, create a brush and then make most sides “textures / common / portalnodraw” and one side "textures / common / portal".



	portalnodraw is just like nodraw but is designed to be used with portal.		portalnodraw is just like nodraw but is designed to be used with portal.


			*Only structural brushes can make up the other walls of a cell with portals. Open a map and filter out the patches (Alt-3), detail brushes (Ctrl-d) and entities (Alt-2) and observe whats left. Usually this will be just a few simple walls, the sky and some caulk brushes. This is what the portal render “sees”.
	Only structural brushes can make up the other walls of a cell with portals. Open a map and filter out the patches (Alt-3), detail brushes (Ctrl-d) and entities (Alt-2) and observe whats left. Usually this will be just a few simple walls, the sky and some caulk brushes. This is what the portal render “sees”.



	Portals are not allowed to have the same cell on both sides. If the compiler detects this, it will ignore the portal and issue a warning. This is known as a portal leak and it will generate a .lin file the same as a regular leak.		*Portals are not allowed to have the same cell on both sides. If the compiler detects this, it will ignore the portal and issue a warning. This is known as a portal leak and it will generate a .lin file the same as a regular leak.



	Portals are not allowed to have one side completely against a solid brush (partially is okay, including partially inside solid). If the compiler detects this, it will ignore the portal and issue a warning.		*Portals are not allowed to have one side completely against a solid brush (partially is okay, including partially inside solid). If the compiler detects this, it will ignore the portal and issue a warning.



	Portals are not allowed the T-junction with other portals. The portal whose face is touching the edge of the other perpendicular portal must have its face split along the edge it shares with that portal.		*Portals are not allowed the T-junction with other portals. The portal whose face is touching the edge of the other perpendicular portal must have its face split along the edge it shares with that portal.



	An example of placing 2 portals to cull geometry around a corner: The diagonal portals here each share 1 edge exactly on the inside corner of this hallway. Cell number 1 can not see the portal face which divides cell 2 from cell 3. Since it can not see this portal, it does not draw the triangles inside cell 3.		*An example of placing 2 portals to cull geometry around a corner: The diagonal portals here each share 1 edge exactly on the inside corner of this hallway. Cell number 1 can not see the portal face which divides cell 2 from cell 3. Since it can not see this portal, it does not draw the triangles inside cell 3.


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	Another example. Position 4 can see through the portal into the cell where position 5 is, however... frustum culling keeps the observer at position 4 from drawing the object at position 5.		*Another example. Position 4 can see through the portal into the cell where position 5 is, however... frustum culling keeps the observer at position 4 from drawing the object at position 5.

Zeroy at 08:39, 17 October 2008

2008-10-17T08:39:08Z

← Older revision		Revision as of 08:39, 17 October 2008
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	{{warning_radiant}}		{{warning_radiant}}
	[[Image:~~Under-Construction~~.gif\|100px\|center]]		[[Image:Uc.gif\|100px\|center]]
	[[Image:Nutshell.png]] Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.		[[Image:Nutshell.png]] Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.

Zeroy at 08:37, 17 October 2008

2008-10-17T08:37:00Z

← Older revision		Revision as of 08:37, 17 October 2008
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	{{warning_radiant}}		{{warning_radiant}}
			[[Image:Under-Construction.gif\|100px\|center]]
	[[Image:Nutshell.png]] Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.		[[Image:Nutshell.png]] Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.

Zeroy at 08:34, 17 October 2008

2008-10-17T08:34:38Z

← Older revision		Revision as of 08:34, 17 October 2008
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	{{~~radiant~~}}		{{warning_radiant}}
	[[Image:Nutshell.png]] Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.		[[Image:Nutshell.png]] Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.

Zeroy: /* Quick Intro */

2008-10-17T08:33:14Z

Quick Intro

← Older revision		Revision as of 08:33, 17 October 2008
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	Portals gives better culling than PVS since they effectively do the exact cell-to-cell PVS for a single view point. Portals can even cull geometry when you turn the mouse, rather than being fixed for a given point. Too many portals can slow the game down because it does too much time calculating what to draw. Portals do frustum culling of triangles~~, (strafe in front of a doorway in CoD2 with r_showtris 1 to observe this in action)~~. Because of this it is not necessary to have portals inside of rooms, only at the windows and doors. Use r_showportals 1 in the game to see where IW placed their portals.		Portals gives better culling than PVS since they effectively do the exact cell-to-cell PVS for a single view point. Portals can even cull geometry when you turn the mouse, rather than being fixed for a given point. Too many portals can slow the game down because it does too much time calculating what to draw. Portals do frustum culling of triangles. Because of this it is not necessary to have portals inside of rooms, only at the windows and doors. Use r_showportals 1 in the game to see where IW placed their portals.

	Too few portals can slow the game down because it quickly decides to draw too much.		Too few portals can slow the game down because it quickly decides to draw too much.

Zeroy: /* Quick Intro */

2008-10-17T08:32:34Z

Quick Intro

← Older revision		Revision as of 08:32, 17 October 2008
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	[[Image:warning.png]] Note: model bounding boxes will get clipped against the portals so they may not get drawn even if they are		[[Image:warning.png]] Note: model bounding boxes will get clipped against the portals so they may not get drawn even if they are
	in a cell that is drawn.		in a cell that is drawn.

Zeroy: /* Quick Intro */

2008-10-17T08:32:28Z

Quick Intro

← Older revision		Revision as of 08:32, 17 October 2008
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	[[Image:warning.png]] Note: model bounding boxes will get clipped against the portals so they may not get		[[Image:warning.png]] Note: model bounding boxes will get clipped against the portals so they may not get drawn even if they are
	drawn even if they are in a cell that is drawn.		in a cell that is drawn.

Zeroy at 08:32, 17 October 2008

2008-10-17T08:32:07Z

← Older revision		Revision as of 08:32, 17 October 2008
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	{{~~Radiant~~}}		{{radiant}}
	[[Image:Nutshell.png]] Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals. Every non-solid part of the map exists in exactly one cell. Cells can have any arbitrary shape, such as L or cube. Portals connect two cells. The classic example is doorways in a house, where each room is a cell and the doorways are portals.		[[Image:Nutshell.png]] Portals divide the world into cells. Each cell is a non-solid, non-detail volume inside the BSP that does not cross any portals.

	== Quick Intro ==		== Quick Intro ==

			Every non-solid part of the map exists in exactly one cell. Cells can have any arbitrary shape, such as L or cube. Portals connect two cells. The classic example is doorways in a house, where each room is a cell and the doorways are portals.

	Whenever a cell is determined to be at least partially visible, all of the world geometry in that cell gets drawn. If a world surface exists on both sides of a portal, it gets drawn if either of the two cells are drawn.		Whenever a cell is determined to be at least partially visible, all of the world geometry in that cell gets drawn. If a world surface exists on both sides of a portal, it gets drawn if either of the two cells are drawn.
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	Note: model bounding boxes will get clipped against the portals so they may not get drawn even if they are in a cell that is drawn.		[[Image:warning.png]] Note: model bounding boxes will get clipped against the portals so they may not get
			drawn even if they are in a cell that is drawn.