Method GL.glRenderMode()

Method glRenderMode

void glRenderMode(int mode)

Description

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

GL_RENDER	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.
GL_SELECT	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.
GL_FEEDBACK	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:

GL_RENDER	0.
GL_SELECT	The number of hit records transferred to the select buffer.
GL_FEEDBACK	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.

Parameter mode

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

Throws

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.