glRenderMode: set rasterization mode.
C Specification |
Associated Gets |
glRenderMode sets the rasterization mode. It takes one argument,
mode, which can assume one of three predefined values:
- Specifies the rasterization mode. Three values are accepted:
GL_RENDER, GL_SELECT, and
GL_FEEDBACK. The initial value is
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:
- Render mode. Primitives are rasterized, producing pixel fragments, which
are written into the frame buffer. This is the normal mode and also the
- 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.
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.
- The number of hit records transferred to the select buffer.
- The number of values (not vertices) transferred to the feedback buffer.
glGet with argument
- 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
- 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
- GL_INVALID_OPERATION is generated if glRenderMode is executed between the
execution of glBegin and the
corresponding execution of glEnd.