GLRENDERMODE(3G) GLRENDERMODE(3G)

glRenderMode - set rasterization mode

GLint glRenderMode( GLenum mode )












  

  
Specifies the rasterization mode. Three values are accepted:
      GL_RENDER, GL_SELECT, and GL_FEEDBACK. The initial
      value is GL_RENDER.










glRenderMode sets the rasterization mode. It takes one
    argument, mode, which can assume one of three predefined values:



  

  
Render mode. Primitives are rasterized, producing pixel fragments, which
      are written into the frame buffer. This is the normal mode and also the
      default mode.

  

  
Selection mode. No pixel fragments are produced, and no change to the
      frame buffer contents is made. Instead, a record of the names of
      primitives that would have been drawn if the render mode had been
      GL_RENDER is returned in a select buffer, which must be created
      (see glSelectBuffer) before selection mode is entered.

  

  
Feedback mode. No pixel fragments are produced, and no change to the frame
      buffer contents is made. Instead, the coordinates and attributes of
      vertices that would have been drawn if the render mode had been
      GL_RENDER is returned in a feedback buffer, which must be created
      (see glFeedbackBuffer) before feedback mode is entered.




The return value of glRenderMode is determined by the
    render mode at the time glRenderMode is called, rather than by
    mode. The values returned for the three render modes are as
  follows:



  

  
0.

  

  
The number of hit records transferred to the select buffer.

  

  
The number of values (not vertices) transferred to the feedback
    buffer.




See the glSelectBuffer and glFeedbackBuffer
    reference pages for more details concerning selection and feedback
    operation.








If an error is generated, glRenderMode returns 0 regardless
    of the current render mode.








GL_INVALID_ENUM is generated if mode is not one of
    the three accepted values.


GL_INVALID_OPERATION is generated if glSelectBuffer
    is called while the render mode is GL_SELECT, or if
    glRenderMode is called with argument GL_SELECT before
    glSelectBuffer is called at least once.


GL_INVALID_OPERATION is generated if
    glFeedbackBuffer is called while the render mode is
    GL_FEEDBACK, or if glRenderMode is called with argument
    GL_FEEDBACK before glFeedbackBuffer is called at least
  once.


GL_INVALID_OPERATION is generated if glRenderMode is
    executed between the execution of glBegin and the corresponding
    execution of glEnd.








glGet with argument GL_RENDER_MODE








glFeedbackBuffer, glInitNames, glLoadName,
    glPassThrough, glPushName, glSelectBuffer