HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 151

F glFeedbackBuffer in the feedback buffer. It can also occur after polygons with more than three edges are broken up into triangles, if the GL implementation renders polygons by performing this decomposition. The glPassThrough command can be used to insert a marker into the feedback buffer. See glPassThrough. Following is the grammar for the blocks of values written into the feedback buffer. Each primitive is indicated with a unique identifying value followed by some number of vertices. Polygon entries include an integer value indicating how many vertices follow. A vertex is fed back as some number of floating-point values, as determined by type. Colors are fed back as four values in RGBA mode and one value in color index mode. feedbackList ← feedbackItem feedbackList | feedbackItem feedbackItem ← point | lineSegment | polygon | bitmap | pixelRectangle | passThru point ← GL_POINT_TOKEN vertex lineSegment ← GL_LINE_TOKEN vertex vertex | GL_LINE_RESET_TOKEN vertex vertex polygon ← GL_POLYGON_TOKEN n polySpec polySpec ← polySpec vertex | vertex vertex vertex bitmap ← GL_BITMAP_TOKEN vertex pixelRectangle ← GL_DRAW_PIXEL_TOKEN vertex |GL_COPY_PIXEL_TOKEN vertex passThru ← GL_PASS_THROUGH_TOKEN value vertex ← 2d | 3d | 3dColor | 3dColorTexture | 4dColorTexture 2d ← value value 3d ← value value value 3dColor ← value value value color 3dColorTexture ← value value value color tex 4dColorTexture ← value value value value color tex color ← rgba | index rgba ← value value value value index ← value tex ← value value value value value is a floating-point number, and n is a floating-point integer giving the number of vertices in the polygon. GL_POINT_TOKEN, GL_LINE_TOKEN, GL_LINE_RESET_TOKEN, GL_POLYGON_TOKEN, GL_BITMAP_TOKEN, GL_DRAW_PIXEL_TOKEN, GL_COPY_PIXEL_TOKEN and GL_PASS_THROUGH_TOKEN are symbolic floating-point constants. GL_LINE_RESET_TOKEN is returned whenever the line stipple pattern is reset. The data returned as a vertex depends on the feedback type. Chapter 6 151