Comparison with a signed expression and unsigned value is converted to unsigned value, reason for minus value is interpreted as a big unsigned value. For this case the "for" loop is going into unexpected behavior.
v1: Brian Paul: code style fix. v2: Ian Romanick: glDrawArrays(GL_QUADS, 0, (n * 4) + k) fail , k < 4. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=38109 Signed-off-by: Marius Predut <marius.pre...@intel.com> --- src/mesa/tnl_dd/t_dd_dmatmp.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/mesa/tnl_dd/t_dd_dmatmp.h b/src/mesa/tnl_dd/t_dd_dmatmp.h index 7be3954..f99d977 100644 --- a/src/mesa/tnl_dd/t_dd_dmatmp.h +++ b/src/mesa/tnl_dd/t_dd_dmatmp.h @@ -627,6 +627,13 @@ static void TAG(render_quads_verts)( struct gl_context *ctx, LOCAL_VARS; GLuint j; + /* Page 18 (page 32 of the PDF) of the OpenGL 2.1 spec says: + * The total number of vertices between Begin and End is 4n + k, + * where 0 ??? k ??? 3; if k is not zero, the final k vertices are ignored. + */ + count = (count / 4) * 4; + if(count == 0) return; + INIT(GL_TRIANGLES); for (j = start; j < count-3; j += 4) { -- 1.9.1
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