These values are supposed to be the minimum/maximum index values used to
read from the vertex buffers. This code either copies index values out of
the old IB (so, same min/max as the original draw call), or generates a
new IB (using index values between the start and the start + count of the
old array draw info, which just happens to be what min/max_index are set
to by st_draw.c).
We were incorrectly setting the max_index in the
converting-from-glDrawArrays case to the start vertex plus the number of
vertices generated in the new IB, which broke QUADS primitive conversion
on VC4 (where max_index really has to be correct, or the kernel might
reject your draw call due to buffer overflow).
Reviewed-by: Rob Clark <robcl...@freedesktop.org> (from verbal description
of the patch)
---
src/gallium/auxiliary/indices/u_primconvert.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/src/gallium/auxiliary/indices/u_primconvert.c
b/src/gallium/auxiliary/indices/u_primconvert.c
index f2a77ce..abcf0d7 100644
--- a/src/gallium/auxiliary/indices/u_primconvert.c
+++ b/src/gallium/auxiliary/indices/u_primconvert.c
@@ -121,6 +121,8 @@ util_primconvert_draw_vbo(struct primconvert_context *pc,
memset(&new_ib, 0, sizeof(new_ib));
util_draw_init_info(&new_info);
new_info.indexed = true;
+ new_info.min_index = info->min_index;
+ new_info.max_index = info->max_index;
if (info->indexed) {
u_index_translator(pc->primtypes_mask,
@@ -152,13 +154,9 @@ util_primconvert_draw_vbo(struct primconvert_context *pc,
&dst_transfer);
if (info->indexed) {
- new_info.min_index = 0;
- new_info.max_index = ~0;
trans_func(src, info->start, new_info.count, dst);
}
else {
- new_info.min_index = info->start;
- new_info.max_index = info->start + new_info.count;
gen_func(info->start, new_info.count, dst);
}
--
2.0.1
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