glRenderMode(3gl)

1GLRENDERMODE(3G)                                              GLRENDERMODE(3G)
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NAME

6       glRenderMode - set rasterization mode
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C SPECIFICATION

10       GLint glRenderMode( GLenum mode )
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PARAMETERS

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

19       glRenderMode sets the rasterization mode.  It takes one argument, mode,
20       which can assume one of three predefined values:
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22       GL_RENDER       Render mode. Primitives are rasterized, producing pixel
23                       fragments,  which  are  written  into the frame buffer.
24                       This is the normal mode and also the default mode.
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26       GL_SELECT       Selection mode.  No pixel fragments are  produced,  and
27                       no  change  to  the  frame  buffer  contents  is  made.
28                       Instead, a record of the names of primitives that would
29                       have  been  drawn if the render mode had been GL_RENDER
30                       is returned in a select buffer, which must  be  created
31                       (see glSelectBuffer) before selection mode is entered.
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33       GL_FEEDBACK     Feedback mode.  No pixel fragments are produced, and no
34                       change to the frame buffer contents is made.   Instead,
35                       the  coordinates  and attributes of vertices that would
36                       have been drawn if the render mode had  been  GL_RENDER
37                       is returned in a feedback buffer, which must be created
38                       (see glFeedbackBuffer) before feedback mode is entered.
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40       The return value of glRenderMode is determined by the  render  mode  at
41       the  time  glRenderMode  is  called,  rather  than by mode.  The values
42       returned for the three render modes are as follows:
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44       GL_RENDER       0.
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46       GL_SELECT       The number of hit records  transferred  to  the  select
47                       buffer.
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49       GL_FEEDBACK     The  number of values (not vertices) transferred to the
50                       feedback buffer.
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52       See the glSelectBuffer and glFeedbackBuffer reference  pages  for  more
53       details concerning selection and feedback operation.
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NOTES

56       If an error is generated, glRenderMode returns 0 regardless of the cur‐
57       rent render mode.
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ERRORS

60       GL_INVALID_ENUM is generated if mode is not one of the  three  accepted
61       values.
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63       GL_INVALID_OPERATION is generated if glSelectBuffer is called while the
64       render mode is GL_SELECT, or if glRenderMode is  called  with  argument
65       GL_SELECT before glSelectBuffer is called at least once.
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67       GL_INVALID_OPERATION  is  generated if glFeedbackBuffer is called while
68       the render mode is GL_FEEDBACK, or if glRenderMode is called with argu‐
69       ment GL_FEEDBACK before glFeedbackBuffer is called at least once.
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71       GL_INVALID_OPERATION  is  generated if glRenderMode is executed between
72       the execution of glBegin and the corresponding execution of glEnd.
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ASSOCIATED GETS

75       glGet with argument GL_RENDER_MODE
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