Article #1 - Purpose, Theory, and Practice
This is the first in a series of mini tutorials on how to do things related to game development. Most will cover the art side of things, some will cover light coding and scripting, and a few will be soley on the theory of game art and or why things are done the way they are.
The software mainly used for these examples will be Maya. The basic toolset is the same between any of the recent versions of maya including the Personal Learning Edition. Few, if any, of the techniques to be presented are maya specific, though the precise steps entailed for any given technique will vary from program to program.
3d Concepts and Vocabulary-Terms you should know.
Geometry - polygonal structure of your model. If someone comments that your Geo is bad, they are saying the structure of your model is poor.
Element/Component - Any geometric piece of a model. Faces, verticies, edges.
Polygon - a 3d geometric shape consisting of at least 3 edges/points.
Tri - Triangle The simplest renderable 3d shape. Triangles are your friend. Triangles are the only polygonal shape that can be rendered. Polygons with more sides are internaly broken down into triangles before display. Triangles are the only polygon that is guaranteed to be planer. That is all its points lie in the same 3d geometric plane.
Quad - Quadrangle A 4 sided polygon. Quads break down into 2 tris, but more importanly quads readily subdivide into 4 smaller quads rather than complex shapes or nested triangles. This makes quads very desireable for modeling toward a high poly end object, or for export into sub-d modeling programs such as silo, Zbrush, and Mudbox.
Ngon - Polygon with more than 4 sides. usually polygon with N sides.
Edge - a side of a polygon connecting 2 points. Edges are used in the techinque of Strip modeling.
Face - The area bounded by a polygon's edges. usefull for area tweeks and extrusion modeling techiniques.
Point/Vertex - The basic building block of any geometric shape. Verticies can be directly manipulated to alter the shape of an object, and in some modeling programs can be directly created and bound into new polygons.
Polygon Flow/edge flow/Face flow - The harmonic layout of geometry in an object. Whether the edges flow where the edges should be in an object. If you are modeling a human torso do the polygons follow the muscles and lines of stress in the object? Having good flow makes for better deformation when animating.
Good Edge Flow
Bad Edge Flow
Deformation - Displacement of a model under influence of bones, deformers, or other tools. Usually refers to bones and animation.
Watertight - Meaning a model is a single solid piece of geometry with no interpenetration etc. As in if you made it in real life it could hold water. This has long since stopped being a concern to game artists, however a watertight model is still needed for applicaitons such as steriolithography or other physical productions.
Edge loop - A set of edges which forms a continuous "ring" around the model. Important for good edge flow and deformation.
Tools
Select - Maya and Max defaults to "q". Lightwave has the select tool as its default state. Press space to drop the current tool. Allows selection of elements without manipulating them Can usually band select by draging the left mouse button.
Translate/Move - In maya and 3ds max this tool defaults to "w" Lightwave default "t".
Rotate -Maya and max default "e" Lightwave default "y".
Scale - Max and maya default "r" Lightwave Uniform scale "H" individual axis scale "h".
Face Extrusion - A tool which allows you to pick faces, then pull them (extrude them) outward from the base object. Technique related to Box Modeling
Edge Extrusion - A tool/technique which allows you to pick edges and extrude them away from their source. Technique also known as Strip Modeling.
Poke faces - Tool which subdivides selected faces by adding a vertex in the center of the face. creates one face per edge of the original polygon. Usefull for making spikes and other pointy bits.
Cut faces - Tool allowing for manual subdivision of individual faces along a new edge. Detailing tool
Split Edge Ring (Bandsaw in lightwave) - Tool which creates a new set of edges inbetween 2 existing sets. Works only with quads.
Cut faces tool (knife tool in Lightwave) - tool which subdivides polygons using a projected line. Fairly inaccurate, but fast. Usefull for cutting objects at a specific angle or gridline.
Bevel - Combination of an extrude and scale operation on a polygon. Has its own tool as its often just that usefull.
Flip Edge - Works only on triangles. Usefull for manual control of edge placement in complicated areas. A detailing/finishing tool usually.
Techniques
Box Modeling - Technique similar to sculpting. Starting with a subdivided box or cylinder the shape is roughed out and detail added by adding edges to the geometry, and progressively refining the shape to the desired level of detail.
usually results in very predictable edge flow, and mostly quads. It can be difficult to get detail effiecently untill you get used to the technique.
Strip Modeling - Using edge extrusion to build strips of geometry defining the shape of a model. Similar in concept to paper machet. Can result in very bad edge flow and geometry if you don't plan ahead, however it can be a very efficent and straight forward form of modeling.
more to come as needed...
The software mainly used for these examples will be Maya. The basic toolset is the same between any of the recent versions of maya including the Personal Learning Edition. Few, if any, of the techniques to be presented are maya specific, though the precise steps entailed for any given technique will vary from program to program.
3d Concepts and Vocabulary-Terms you should know.
Geometry - polygonal structure of your model. If someone comments that your Geo is bad, they are saying the structure of your model is poor.
Element/Component - Any geometric piece of a model. Faces, verticies, edges.
Polygon - a 3d geometric shape consisting of at least 3 edges/points.
Tri - Triangle The simplest renderable 3d shape. Triangles are your friend. Triangles are the only polygonal shape that can be rendered. Polygons with more sides are internaly broken down into triangles before display. Triangles are the only polygon that is guaranteed to be planer. That is all its points lie in the same 3d geometric plane.
Quad - Quadrangle A 4 sided polygon. Quads break down into 2 tris, but more importanly quads readily subdivide into 4 smaller quads rather than complex shapes or nested triangles. This makes quads very desireable for modeling toward a high poly end object, or for export into sub-d modeling programs such as silo, Zbrush, and Mudbox.
Ngon - Polygon with more than 4 sides. usually polygon with N sides.
Edge - a side of a polygon connecting 2 points. Edges are used in the techinque of Strip modeling.
Face - The area bounded by a polygon's edges. usefull for area tweeks and extrusion modeling techiniques.
Point/Vertex - The basic building block of any geometric shape. Verticies can be directly manipulated to alter the shape of an object, and in some modeling programs can be directly created and bound into new polygons.
Polygon Flow/edge flow/Face flow - The harmonic layout of geometry in an object. Whether the edges flow where the edges should be in an object. If you are modeling a human torso do the polygons follow the muscles and lines of stress in the object? Having good flow makes for better deformation when animating.
Good Edge Flow
Bad Edge Flow
Deformation - Displacement of a model under influence of bones, deformers, or other tools. Usually refers to bones and animation.
Watertight - Meaning a model is a single solid piece of geometry with no interpenetration etc. As in if you made it in real life it could hold water. This has long since stopped being a concern to game artists, however a watertight model is still needed for applicaitons such as steriolithography or other physical productions.
Edge loop - A set of edges which forms a continuous "ring" around the model. Important for good edge flow and deformation.
Tools
Select - Maya and Max defaults to "q". Lightwave has the select tool as its default state. Press space to drop the current tool. Allows selection of elements without manipulating them Can usually band select by draging the left mouse button.
Translate/Move - In maya and 3ds max this tool defaults to "w" Lightwave default "t".
Rotate -Maya and max default "e" Lightwave default "y".
Scale - Max and maya default "r" Lightwave Uniform scale "H" individual axis scale "h".
Face Extrusion - A tool which allows you to pick faces, then pull them (extrude them) outward from the base object. Technique related to Box Modeling
Edge Extrusion - A tool/technique which allows you to pick edges and extrude them away from their source. Technique also known as Strip Modeling.
Poke faces - Tool which subdivides selected faces by adding a vertex in the center of the face. creates one face per edge of the original polygon. Usefull for making spikes and other pointy bits.
Cut faces - Tool allowing for manual subdivision of individual faces along a new edge. Detailing tool
Split Edge Ring (Bandsaw in lightwave) - Tool which creates a new set of edges inbetween 2 existing sets. Works only with quads.
Cut faces tool (knife tool in Lightwave) - tool which subdivides polygons using a projected line. Fairly inaccurate, but fast. Usefull for cutting objects at a specific angle or gridline.
Bevel - Combination of an extrude and scale operation on a polygon. Has its own tool as its often just that usefull.
Flip Edge - Works only on triangles. Usefull for manual control of edge placement in complicated areas. A detailing/finishing tool usually.
Techniques
Box Modeling - Technique similar to sculpting. Starting with a subdivided box or cylinder the shape is roughed out and detail added by adding edges to the geometry, and progressively refining the shape to the desired level of detail.
usually results in very predictable edge flow, and mostly quads. It can be difficult to get detail effiecently untill you get used to the technique.
Strip Modeling - Using edge extrusion to build strips of geometry defining the shape of a model. Similar in concept to paper machet. Can result in very bad edge flow and geometry if you don't plan ahead, however it can be a very efficent and straight forward form of modeling.
more to come as needed...
posted by -V at 8:13 PM
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