The third parameter, numpoints , is the length of the properties array and is the number of floating point numbers contained within the array. The fourth parameter, properties , is the properties array, which is a list of properties to be assigned to the material, light source, or lighting model. Values in the array are property identifiers, each followed by the appropriate number of data values. All identifiers and data values are floating-point numbers. Only property identifiers appropriate for the object being defined should be included in the properties array.
All properties have default values that have been chosen for their efficient execution.
The first time a material, light, or lighting property is defined, it is initialized to the default values. Incremental changes can be made to a material, light source, or lighting model definition. Each call to the lmdef subroutine changes only the properties included in its properties array. Properties that are not specified in the properties array keep their previous values. Any valid property can be changed regardless of whether that property is relevant to the current lighting calculation.