Mesh and LOD - Revision history

Atami Merlin: translation

2012-12-20T08:53:40Z

translation

← Older revision		Revision as of 01:53, 20 December 2012
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			{{multi-lang}}
	==Level Of Detail==		==Level Of Detail==

Misty Mole: Removed Sylvan's background information to a new mesh background page

2012-12-10T11:47:54Z

Removed Sylvan's background information to a new mesh background page

← Older revision		Revision as of 04:47, 10 December 2012
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	~~==Mesh basics==~~
	~~A ''mesh'' is of a collection of vertices, edges, and faces that define a 3D shape.~~

	~~[[File:vertices black640.png\|320px]]~~
	~~The basic element of a mesh is a ''vertex''. Vertices represent points in space.~~

	~~[[File:edges 640.png\|320px]]~~
	~~''Edges'' are lines that connect two vertices.~~

	~~[[File:triangle6401.png\|320px]]~~
	~~A ''face'' is a triangle composed of three vertices connected by edges.~~


	~~[[File:Mesh Image640.png\|320px]]~~
	~~Together, they can combine to make models that look like this!~~

	~~==File Format==~~
	Second Life can import meshes in the COLLADA 1.4.1 (.dae) file format. COLLADA is a powerful open standard format consisting of human-readable XML. Although Second Life uses COLLADA for importing mesh data, it internally uses a custom format for uploading, storage, and streaming of mesh content.

	{{KBnote\|While the COLLADA spec supports everything from polygons to nurbs, the Second Life mesh importer only imports polygonal data. This means that you must convert your models to meshes before exporting to a COLLADA file.}}

	~~More than you'll ever need to know about COLLADA:~~
	* [http://en.wikipedia.org/wiki/COLLADA COLLADA on Wikipedia]
	* [https://collada.org/mediawiki/index.php/COLLADA_-_Digital_Asset_and_FX_Exchange_Schema Digital Asset and FX Exchange Schema]
	* [http://wiki.secondlife.com/wiki/Mesh/Mesh_Asset_Format Second Life internal mesh format spec]

	~~==Software==~~

	~~There are many applications that can create mesh and export to COLLADA. Here is a short list of some popular tools:~~

	* [http://usa.autodesk.com/maya/ Maya]
	* [http://usa.autodesk.com/3ds-max/ 3dsMax] Many other Autodesk tools can also export to COLLADA.
	* [http://www.blender.org/ Blender] Additional Second Life Mesh Blender specific tutorials here: [http://blog.machinimatrix.org/ http://blog.machinimatrix.org/] and [http://cgcookie.com http://cgcookie.com]
	* [http://www.wings3d.com/ Wings 3D] No UV mapping tool.
	* [http://www.daz3d.com/ Daz Studio]

	~~Many other software packages can create mesh, though some may require minor settings adjustments or even external programs to generate .dae files.~~

	~~Here is a more extensive list on the Second Life Wiki: [[Mesh/Tools]]~~

	~~Here are some examples of files in COLLADA .dae file format. [[Mesh/Sample_Content]]~~


	==Level Of Detail==		==Level Of Detail==

Jeremy Linden: /* Best practices hit list */

2012-11-28T17:54:16Z

Best practices hit list

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	Most modeling software packages have features built in to facilitate this technique.		Most modeling software packages have features built in to facilitate this technique.

	~~==Best practices hit list==~~
	*Low poly count.
	*Smart UV mapping for efficient texture use and size.
	*Smart LOD settings and files.
	*Smart appropriately Analyzed simple physic shapes.

Jeremy Linden: /* Low polygon modeling */

2012-11-28T17:53:53Z

Low polygon modeling

← Older revision		Revision as of 10:53, 28 November 2012
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	==Low polygon modeling==		==Low polygon modeling==

	We are ~~not making the next Avatar movie, we are streaming~~ triangles and data near the speed of light. Make sure each and every polygon and bit counts.		It is important to remember that Hollywood-quality digital models are extremely costly to use in Second Life. Real-time rendering means Second Life must stream triangles and data near the speed of light. Make sure each and every polygon and bit counts!
	There are many low polygon modeling techniques and software specific tutorials and tools available around the web. ~~[http://en.wikipedia.org/wiki/Low_poly]~~		There are many [http://en.wikipedia.org/wiki/Low_poly low polygon] modeling techniques and software-specific tutorials and tools available around the web.

	The goal ~~should always be~~ to save every triangle ~~everywhere~~ you can on the model you plan to upload.		The goal is to save every triangle you can on the model you plan to upload:
	*Ensure that any flat surface uses the ~~least amount~~ of ~~faces as~~ possible.		*Ensure that any flat surface uses the smallest number of triangles possible.
	*Use ~~Smooth Normals~~ to fake smooth curved surfaces.		*Use smooth normals to "fake" smooth curved surfaces.
	*Use a low polygon rendering tricks to bake detailed textures.		*Use low polygon rendering tricks to bake detailed textures, which can provide the illusion of more geometric detail.

	===Low ~~Poly Texture~~ baking tricks===		===Low polygon texture baking tricks===
	~~The idea~~ is to create a very highly detailed model and use it to render gorgeous textures on to a very simple low ~~poly~~ Second Life friendly version.		It is possible to create a very highly detailed model and use it to render gorgeous textures on the faces of a very simple low polygon (Second Life friendly) version.
	~~Making~~ the name low ~~poly~~ modeling slightly deceptive~~. As~~ you will ~~most likely~~ model and render a very high ~~poly~~ scene. ~~But~~, the ~~result~~ is a very efficient model with very detailed textures~~, well poised for incoming Normal and Specular maps~~.		In this case, the name "low polygon modeling" sounds slightly deceptive because you will model and render a very high polygon scene for the purposes of creating the textured illusion. However, the final product is a very efficient, low-polygon model with very detailed textures mapped onto it.

	Most modeling software packages have features built in to facilitate this technique~~. Look up your favorites', it will be time very well spent~~.		Most modeling software packages have features built in to facilitate this technique.

	==Best practices hit list==		==Best practices hit list==

Jeremy Linden: /* Normals */

2012-11-28T17:44:19Z

Normals

← Older revision		Revision as of 10:44, 28 November 2012
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	==Normals==		==Normals==
	A ~~''normal'' is something that is perpendicular to a plane.~~ [http://en.wikipedia.org/wiki/Normal_%28geometry%29]		A [http://en.wikipedia.org/wiki/Normal_%28geometry%29 ''normal''] is something that is perpendicular to a plane.
	For the scope of this article, normal describes the direction a face is pointing. Most 3D renderers, the Second Life Viewer included, smartly render only one side of a face. This saves cycles but assumes model is ''manifold'' (enclosed in a way that won't encourage views inline with the normal, or are double sided where needed)		For the scope of this article, normal describes the direction a face is pointing. Most 3D renderers, the Second Life Viewer included, smartly render only one side of a face. This saves cycles but assumes model is ''manifold'' (enclosed in a way that won't encourage views inline with the normal, or are double sided where needed)

Jeremy Linden: /* Normals */

2012-11-28T17:43:42Z

Normals

← Older revision		Revision as of 10:43, 28 November 2012
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	For the scope of this article, normal describes the direction a face is pointing. Most 3D renderers, the Second Life Viewer included, smartly render only one side of a face. This saves cycles but assumes model is ''manifold'' (enclosed in a way that won't encourage views inline with the normal, or are double sided where needed)		For the scope of this article, normal describes the direction a face is pointing. Most 3D renderers, the Second Life Viewer included, smartly render only one side of a face. This saves cycles but assumes model is ''manifold'' (enclosed in a way that won't encourage views inline with the normal, or are double sided where needed)

	[[File:normal and flipped normal sphere.png]]		[[File:normal and flipped normal sphere.png\|256px]]
	Two spheres. Left: Normals pointing out, Right: Normals pointing in.		Two spheres. Left: Normals pointing out, Right: Normals pointing in.

Jeremy Linden: /* Smooth Normals */

2012-11-28T17:43:05Z

Smooth Normals

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	In the case of a round or curved multiple face surface, a normal average can be used. A normal average allows inexpensive surface smoothing. Commonly known as "smooth normals" or "smooth shading", it is an invaluable tool when creating low polygon Second Life content. Smooth normals allow fewer faces to appear as a visually smooth surface, requiring far fewer faces. For example, a five-sided cylinder with smooth normals can appear completely round in Second Life. In some cases, a even a three-sided cylinder can appear perfectly round.		In the case of a round or curved multiple face surface, a normal average can be used. A normal average allows inexpensive surface smoothing. Commonly known as "smooth normals" or "smooth shading", it is an invaluable tool when creating low polygon Second Life content. Smooth normals allow fewer faces to appear as a visually smooth surface, requiring far fewer faces. For example, a five-sided cylinder with smooth normals can appear completely round in Second Life. In some cases, a even a three-sided cylinder can appear perfectly round.

	[[File:smooth cylinder next to not smooth.png]]		{\|
	Two five-sided cylinders. Top: Solid normals. Bottom: Smooth normals.		\|-
			\|[[File:smooth cylinder next to not smooth.png\|256px]]
			\|Two five-sided cylinders. Top: Solid normals. Bottom: Smooth normals.
	Note where both cylinders intersect the walls, they show the profile of the actual geometry.		Note where both cylinders intersect the walls, they show the profile of the actual geometry.
			\|-
	Applying smooth normals to some areas and not to others can be useful for adding detail or highlighting edges.		\|[[File:candlestick.png\|256px]]
			\|Applying smooth normals to some areas and not to others can be useful for adding detail or highlighting edges.
	~~[[File:candlestick.png]]~~		\|}

	==Low polygon modeling==		==Low polygon modeling==

Jeremy Linden: /* Normals */

2012-11-28T17:40:36Z

Normals

← Older revision		Revision as of 10:40, 28 November 2012
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	==Normals==		==Normals==
	~~Normal~~ is ~~an adjective that describes~~ something that is perpendicular to a plane. [http://en.wikipedia.org/wiki/Normal_%28geometry%29]		A ''normal'' is something that is perpendicular to a plane. [http://en.wikipedia.org/wiki/Normal_%28geometry%29]
	For the scope of this article, normal describes the direction a face is pointing. Most 3d renderers, the Second Life Viewer included, smartly render only one side of a face. This saves cycles but assumes model is ~~Manifold~~ (enclosed in a way that won't encourage views inline with the normal, or are double sided where needed)		For the scope of this article, normal describes the direction a face is pointing. Most 3D renderers, the Second Life Viewer included, smartly render only one side of a face. This saves cycles but assumes model is ''manifold'' (enclosed in a way that won't encourage views inline with the normal, or are double sided where needed)

	[[File:normal and flipped normal sphere.png]]		[[File:normal and flipped normal sphere.png]]
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	===Smooth Normals===		===Smooth Normals===
	In the case of a round or curved multiple face surface, a ~~Normal~~ average can be used~~; which~~ allows an inexpensive surface smoothing. Commonly known as ~~Smooth Normals~~ or ~~Smooth~~ shading, it is an invaluable tool when creating low polygon Second Life content.		In the case of a round or curved multiple face surface, a normal average can be used. A normal average allows inexpensive surface smoothing. Commonly known as "smooth normals" or "smooth shading", it is an invaluable tool when creating low polygon Second Life content. Smooth normals allow fewer faces to appear as a visually smooth surface, requiring far fewer faces. For example, a five-sided cylinder with smooth normals can appear completely round in Second Life. In some cases, a even a three-sided cylinder can appear perfectly round.
	Smooth ~~Normals~~ allow fewer faces to ~~achieve~~ a visually smooth surface~~. Far~~ far fewer faces.
	For example, a five sided cylinder with smooth normals can appear completely round in Second Life. In some cases, a three sided cylinder ~~will~~ appear perfectly round.

	[[File:smooth cylinder next to not smooth.png]]		[[File:smooth cylinder next to not smooth.png]]
	Two 5 sided cylinders. Top: Solid ~~Normals~~. Bottom: Smooth normals.		Two five-sided cylinders. Top: Solid normals. Bottom: Smooth normals.
	Note where both cylinders intersect the walls, they show the profile of the actual geometry.		Note where both cylinders intersect the walls, they show the profile of the actual geometry.

	Applying ~~Smooth Normals~~ to some areas and not to others ~~is another~~ useful for adding detail or highlighting edges.		Applying smooth normals to some areas and not to others can be useful for adding detail or highlighting edges.

	[[File:candlestick.png]]		[[File:candlestick.png]]

Jeremy Linden: /* Texture Faces */

2012-11-28T17:36:06Z

Texture Faces

← Older revision		Revision as of 10:36, 28 November 2012
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	*Each LOD model must all have the same number of Texture faces.		*Each LOD model must all have the same number of Texture faces.
	*All the separate faces need to use the same UV map.		*All the separate faces need to use the same UV map.
	*Each modeling software handles this slightly differently. Assigning different areas to different materials archives separate Texture faces on an uploaded Mesh in some modelers, and assigning areas to separate textures achieves this in others. ~~Application specific information~~ [http://wiki.secondlife.com/wiki/Mesh/Uploading_a_multi-face_mesh]		*Each modeling software handles this slightly differently. Assigning different areas to different materials archives separate Texture faces on an uploaded Mesh in some modelers, and assigning areas to separate textures achieves this in others. [http://wiki.secondlife.com/wiki/Mesh/Uploading_a_multi-face_mesh Here are some examples of application specific information.]

	==Normals==		==Normals==

Jeremy Linden: /* Projection UV mapping */

2012-11-28T17:34:45Z

Projection UV mapping

← Older revision		Revision as of 10:34, 28 November 2012
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	Disadvantages:		Disadvantages:
	**Potential for texture size overuse inworld.		*Potential for texture size overuse inworld.
	**Models uploaded with projection UV maps can not take advantage of modeling software's texture baking capability.		*Models uploaded with projection UV maps can not take advantage of modeling software's texture baking capability.

	====Baking textures====		====Baking textures====