Povray documentation for

ray tracing assignment for CSC 473

Povray objects are defined in ascii text by the object name followed by braces, optional fields (that are usually order independent) and closing braces. Objects in this document will be listed with their default values.

Floats and Vectors  Values in Povray are specified as floating point numbers and vectors. The syntax of a vector is:

< float1 , float2 , float3 >

Comments  Comments are denoted by the // symbol and proceed until the end of the current line (similar to C++ comments).

Camera  Cameras are defined as the following:  

camera {  

location < 0 , 0 , 0 >

 up < 0 , 1 , 0 >  

right < 1.333 , 0 , 0 >  

look_at < 0 , 0, -1 >  

}

 The location field specifies the location of the camera. The up direction specifies the vector pointing out of the top of the camera and the right vector specifies the vector pointing out of the right of the camera. The look_at field determines which way the camera is facing. While the up and right fields define the orientation of the camera, they also determine the size of the image plane. The image plane is located one unit from the camera location. It has dimensions corresponding to the sizes of the right and up vectors (centered around the origin). This determines where a specific ray must for a given pixel. (Note that the camera vectors may need to be orthogonalized - do it in the order look_at, up, right)

Point Light Sources  Point lights are the illumination for our scene. Light sources have no visible shape, rather they provide light for other objects in the scene. Point lights are defined as follows:  

light_source { < X , Y , Z > color rgb < r , g , b > }  

Where < X , Y , Z > is the light source location and < r , g , b> is the light source color. The light color also determines its intensity. For instance, < 0.5 , 0.5 , 0.5 > is a light source half as bright as < 1 , 1 , 1 >.  

Objects

Objects are the building blocks of your scene. They are what you will finally be seeing in your rendered image. Objects are defined by an object name followed by some object specific fields, followed by some optional modifiers.

objectname {

objectSpecficFields

[modifiers]

}

The objects that you will need in your program are given below.

Box  The box is an axis aligned bow defined by two corners:  

box { < CORNER1 > , < CORNER2 > }  

Where < CORNER1 > and < CORNER2 > are vectors defining the two corners of the box. Corner 1 must be less than corner 2 (in all elements) in order for the box to appear. If one wants a non axis aligned box, the axis aligned box can be rotated translated and scaled like all objects.

Sphere  The sphere is defined by a center point and radius:  

sphere { < CENTER > , RADIUS }

Cone  Cones are defined by two endpoints and two radii:  

cone { < END1 > , RADIUS1 , < END2 > , RADIUS2 }  

Where END1 and END2 define the centers of each end of the cone and RADIUS1 and RADIUS2 are the radii of the cone at those endpoints. Therefore the cone does not have to come to a sharp point at the top and can also designate a cylinder.

Plane  Planes are infinite primitives defined by a normal and distance:  

plane { < NORMAL > , DISTANCE }  

If the NORMAL is defined as < A , B , C > and the DISTANCE as D, then the plane satisfies the equation:  

A * x + B * y + C * z = D

Triangle  Triangles are similar to planes except they don't extend infinitely in all directions. They are usually used to make more complex objects and are defined by 3 vertices:  

triangle { < CORNER1 > , < CORNER2 > , < CORNER3 > }  

Modifiers

Modifiers are fields within objects that alter the current state of the object. Examples of modifiers are transformations, pigments (colors) and finish (surface properties).

Transformations

The transformations on an object are applied in top down order (the first transformation in the object is the first one applied to the object, followed by the second, etc.). The three transformations are: translation, rotation and scaling.

Translation  Translations are defined as relative movements of an object and are specified by a vector:  

translate < TX , TY , TZ >

Rotation  Rotations are specified in Euler angles around the coordinate axes. The order of rotation is x axis, then y axis, then z axis.  

rotate < RX , RY , RZ >

Scaling  Scalings are defined by either a float (uniform scaling) or a vector (nonuniform scaling):  

scale s  

scale < SX , SY , SZ >  

Pigment

Pigment defines the objects color (used in shading calculations). They are defined as rgb triples or rgbf quads where f is the filter component specifying how transparent the object is. The values for the components should lie between 0 and 1. Filter defaults to 0 if unspecified.

pigment { color rgb < R , G , B > }

pigment { color rgbf < R , G , B , F > }

Finish

Finish specifies the surface properties of an object such as reflectance and refractance. It contains optional fields with default values:

finish {

ambient 0.1

diffuse 0.6

specular 0.0

roughness 0.05

reflection 0.0

refraction 0.0

ior 1.0

}

Ambient  Ambient specifies the amount of ambient light the object receives. This is light scattered from many different sources and is extremely hard to calculate in practice.

Diffuse  Diffuse specifies the amount of diffuse light reflected from an object (light reflected in all directions equally).

Specular  Specular specifies the amount of specular reflection (creates highlights).

Roughness  Roughness specifies the size of the specular highlight.

Reflection  Reflection specifies the reflection coefficient of the surface (percentage of light reflected)

Refraction  Refraction turns on refraction for an object (otherwise pure transmission is used).

Ior  Ior specifies the index of refraction of the object.