Gl.RenderMode (gb.opengl)

Static Function RenderMode ( Mode As Integer ) As Array

Set rasterization mode.

Parameters

mode: Specifies the rasterization mode. Three values are accepted: Gl.RENDER, Gl.SELECT, and Gl.FEEDBACK. The initial value is Gl.RENDER.

Description

Gl.RenderMode 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 Gl.SelectBuffer) 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 Gl.FeedbackBuffer) before feedback mode is entered.

The return value of Gl.RenderMode is determined by the render mode at the time Gl.RenderMode 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 Gl.SelectBuffer and Gl.FeedbackBuffer reference pages for more details concerning selection and feedback operation.

Notes

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

Errors

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

Gl.INVALID_OPERATION is generated if Gl.SelectBuffer is called while the render mode is Gl.SELECT, or if Gl.RenderMode is called with argument Gl.SELECT before Gl.SelectBuffer is called at least once.

Gl.INVALID_OPERATION is generated if Gl.FeedbackBuffer is called while the render mode is Gl.FEEDBACK, or if Gl.RenderMode is called with argument Gl.FEEDBACK before Gl.FeedbackBuffer is called at least once.

Gl.INVALID_OPERATION is generated if Gl.RenderMode is executed between the execution of Gl.Begin and the corresponding execution of Gl.End.

Associated Gets

Gl.Get with argument Gl.RENDER_MODE