From 9f8ec533123f07f29b084e8a46fc35c498b3a670 Mon Sep 17 00:00:00 2001 From: Marek Olšák Date: Sun, 17 Jan 2010 23:13:51 +0100 Subject: r300g: fix zero-area scissor --- src/gallium/drivers/r300/r300_emit.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/src/gallium/drivers/r300/r300_emit.c b/src/gallium/drivers/r300/r300_emit.c index e07185b7783..36d2c64b587 100644 --- a/src/gallium/drivers/r300/r300_emit.c +++ b/src/gallium/drivers/r300/r300_emit.c @@ -686,6 +686,22 @@ void r300_emit_scissor_state(struct r300_context* r300, void* state) maxy = MIN2(maxy, scissor->maxy); } + /* Special case for zero-area scissor. + * + * We can't allow the variables maxx and maxy to be zero because they are + * subtracted from later in the code, which would cause emitting ~0 and + * making the kernel checker angry. + * + * Let's consider we change maxx and maxy to 1, which is effectively + * a one-pixel area. We must then change minx and miny to a number which is + * greater than 1 to get the zero area back. */ + if (!maxx || !maxy) { + minx = 2; + miny = 2; + maxx = 1; + maxy = 1; + } + if (r300screen->caps->is_r500) { top_left = (minx << R300_SCISSORS_X_SHIFT) | -- cgit v1.2.3