i965/clear: clear_value better precision

Test-case with depth-clear 0.5 and format
MESA_FORMAT_Z24_UNORM_X8_UINT fails due inconsistent
clear-value of 0.4999997.
Maybe its better to improve?

CC: Jason Ekstrand <jason.ekstrand@intel.com>
Fixes: 0ae9ce0f29ea (i965/clear: Quantize the depth clear value based on the format)
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111113
Signed-off-by: Sergii Romantsov <sergii.romantsov@globallogic.com>
Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

diff --git a/src/mesa/drivers/dri/i965/brw_clear.c b/src/mesa/drivers/dri/i965/brw_clear.c
index 30e09861491e90b3b66d6cf557f189d805d1c97f..1508171da1070d1da223376f778c7d9a41e9575a 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_clear.c
+++ b/src/mesa/drivers/dri/i965/brw_clear.c
@@ -167,7 +167,7 @@ brw_fast_clear_depth(struct gl_context *ctx)
     */
    float clear_value =
       mt->format == MESA_FORMAT_Z_FLOAT32 ? ctx->Depth.Clear :
-      (unsigned)(ctx->Depth.Clear * fb->_DepthMax) / (float)fb->_DepthMax;
+      _mesa_lroundeven(ctx->Depth.Clear * fb->_DepthMax) / (float)(fb->_DepthMax);
 
    const uint32_t num_layers = depth_att->Layered ? depth_irb->layer_count : 1;