NAME

glodAdaptGroup - Adapts a group to a particular LOD based on the bound transform matrices and group settings.

C SPECIFICATION

void glodAdaptGroup(GLuint name)

PARAMETERS

name

The name of the group to adapt

DESCRIPTION

Adaptation of a group is governed using the glodGroupParameter[if] interface. This takes a configuration tag and a value. The configuration options that affect group adaptation are explained below.

The main configuraiton option for a group is its adaption mode. Acceptable values for GLOD_ADAPT_MODE are GLOD_ERROR_THRESHOLD or GLOD_TRIANGLE_BUDGET.

GLOD_ERROR_THRESHOLD parameters

Error threshold mode refines all fo the emmbers of your group to within a certain constant amount of error. The metric for determining this error, as well as the constant error amount, is selectable through the glodGroupParameter interface.

The GLOD_ERROR_MODE setting selects how geometric error is interpreted for this group. Possible error modes are GLOD_OBJECT_SPACE_ERROR or GLOD_SCREEN_SPACE_ERROR. Depending on whether you chose object or screen space error mode, you must also specify the amount of acceptable error for refinement using GLOD_OBJECT_SPACE_ERROR_THRESHOLD or GLOD_SCREEN_SPACE_ERROR_THRESHOLD, depending on your choice of the error mode.

The following code sets group 0 to adapt all of its member objects to a screen-space error of no more than 3 pixels.

  glodGroupParameter(0, GLOD_ADAPT_MODE, GLOD_ERROR_THRESHOLD);
  glodGroupParameter(0, GLOD_ERROR_THRESHOLD, 
                         GLOD_SCREEN_SPACE_ERROR);
  glodGroupParameter(0, GLOD_SCREEN_SPACE_ERROR_THRESHOLD, 3.0f);

GLOD_TRIANGLE_BUDGET parameters

If you set the group to GLOD_TRIANGLE_BUDGET, you must also set the number of triangles that you want the group to contain after adaptation. This is set using GLOD_MAX_TRIANGLES. Additionally, you must set the way in which triangles will be chosen --- with respect to screen space or object space. This is done by setting GLOD_ERROR_MODE to GLOD_OBJECT_SPACE_ERROR or GLOD_SCREEN_SPACE_ERROR.

The following code sets a group to refine to int num_tris triangles using the screen-space appearance of the object as a guide.

  glodGroupParameter(0, GLOD_ADAPT_MODE, GLOD_TRIANGLE_BUDGET);
  glodGroupParameter(0, GLOD_ERROR_MODE, GLOD_SCREEN_SPACE_ERROR_MODE);
  glodGroupParameter(0, GLOD_MAX_TRIANGLES, num_tris);

ERRORS

GLOD_INVALID_NAME is generated if a group of this name does not exist in the system.

GLOD_INVALID_STATE is generated if the adaptation parameters are not set properly.