Performer Graphics Primitives

Performer uses two major classes for its drawing primitives:
pfGeoSet:

Geometry (points, normals, colors, texture coordinates)

Materials

Texture maps

and other drawing state (transparency, fog, etc.)

pfGeoSet

A geoset is a collection of one or more primitives of a certain type.

The primitive types available are:

• points (PFGS_POINTS)
• lines (PFGS_LINES)
• triangles (PFGS_TRIANGLES)
• quadrilaterals (PFGS_QUADS)
• arbitrary polygons (PFGS_POLYS)
• line strips (PFGS_LINESTRIPS)
• triangle strips (PFGS_TRISTRIPS)
• triangle fans (PFGS_TRIFANS)

pfGeoSet data includes:

• Primitive type
• Number of primitives
• Lengths of primitives (an array of ints)
• Attributes:
  • Vertex coordinates (an array of pfVec3s)
  • Normals (an array of pfVec3s)
  • Colors (an array of pfVec4s)
  • Texture coordinates (an array of pfVec2s)
• Geostate
• Bounding box (normally calculated for you by Performer)
• Other options:
  • Drawing mode
  • Line width
  • Point size
  • Drawing bin
  • Intersection mask

pfGeoSet Attributes

Vertex coordinates are required. All other attributes are optional.

Attributes can be indexed or non-indexed. Stick with non-indexed.

Attributes other than vertex coordinates can be defined "overall", "per primitive", or "per vertex". Individual attributes can be defined differently; i.e. a geoset can have per-vertex normals and per-primitive colors.

PFGS_OVERALL:

PFGS_PER_PRIM:

PFGS_PER_VERTEX:

Example Geoset

PrimType: PFGS_TRISTRIPS
NumPrims: 3
PrimLengths: { 5, 4, 4 }

Attributes:

PFGS_COORD3, PFGS_PER_VERTEX, { {x,y,z}1, ..., {x,y,z}13 }

PFGS_NORMAL3, PFGS_PER_VERTEX, { {x,y,z}1, ..., {x,y,z}13 }

PFGS_COLOR4, PFGS_PER_PRIM, { {r,g,b,a}, {r,g,b,a}, {r,g,b,a} }

PFGS_TEXCOORD2, PFGS_OFF

Skeletal C++ code:

	geoset->setPrimType(PFGS_TRISTRIPS);
	geoset->setNumPrims(3);
	/* Create "lengths" - array of 3 int's */
	geoset->setPrimLengths(lengths);
	/* Create "vertices" - array of 13 pfVec3's */
	geoset->setAttr(PFGS_COORD3, PFGS_PER_VERTEX, vertices, NULL);
	/* Create "normals" - array of 13 pfVec3's */
	geoset->setAttr(PFGS_NORMAL3, PFGS_PER_VERTEX, normals, NULL);
	/* Create "colors" - array of 3 pfVec4's */
	geoset->setAttr(PFGS_COLOR4, PFGS_PER_PRIM, colors, NULL);

pfGeoState

Encapsulates the GL rendering state to be applied to a geoset. Anything left undefined is inherited from the global geostate.

Modes:

• Transparency
• Lighting
• Texturing
• Using texture matrix
• Fogging
• Backface culling

• Front / back material
• Lighting model
• Texture map
• Texture environment
• Texture matrix
• Fog

pfMaterial

• Color (ambient, diffuse, specular, emissive)
• Shininess
• Alpha
• Color mode

pfTexture

Can load an RGB image file via

		texture->loadImage("file.rgb") 

or define an image dynamically and use

		texture->setImage(image, 4, x, y, 1); 

Example Ygdrasil Class

The example class strip creates a geoset containing a single triangle strip. The length of the strip can be set by the "length" message, and an optional texture map can be given by the "texture" message.

• strip.h
• strip.cxx