From: Jason Ekstrand Date: Sat, 3 Sep 2016 16:49:24 +0000 (-0700) Subject: intel/blorp: Increase the presision of coordinate transform calculations X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=fa4627149dfe7cdb9f75d8e2f1bcaf1ad7006801;p=mesa.git intel/blorp: Increase the presision of coordinate transform calculations The result of this calculation goes into an fma() in the shader and we would like it to be as precise as possible. The division in particular was a source of imprecision whenever dst1 - dst0 was not a power of two. This prevents regressions in some of the new Vulkan CTS tests for blitting using a filtering of NEAREST. Signed-off-by: Jason Ekstrand Reviewed-by: Topi Pohjolainen Reviewed-by: Kenneth Graunke --- diff --git a/src/intel/blorp/blorp_blit.c b/src/intel/blorp/blorp_blit.c index 0898ed45faa..af463890579 100644 --- a/src/intel/blorp/blorp_blit.c +++ b/src/intel/blorp/blorp_blit.c @@ -1263,7 +1263,7 @@ brw_blorp_setup_coord_transform(struct brw_blorp_coord_transform *xform, GLfloat dst0, GLfloat dst1, bool mirror) { - float scale = (src1 - src0) / (dst1 - dst0); + double scale = (double)(src1 - src0) / (double)(dst1 - dst0); if (!mirror) { /* When not mirroring a coordinate (say, X), we need: * src_x - src_x0 = (dst_x - dst_x0 + 0.5) * scale @@ -1276,7 +1276,7 @@ brw_blorp_setup_coord_transform(struct brw_blorp_coord_transform *xform, * so 0.5 provides the necessary correction. */ xform->multiplier = scale; - xform->offset = src0 + (-dst0 + 0.5f) * scale; + xform->offset = src0 + (-(double)dst0 + 0.5) * scale; } else { /* When mirroring X we need: * src_x - src_x0 = dst_x1 - dst_x - 0.5 @@ -1284,7 +1284,7 @@ brw_blorp_setup_coord_transform(struct brw_blorp_coord_transform *xform, * src_x = src_x0 + (dst_x1 -dst_x - 0.5) * scale */ xform->multiplier = -scale; - xform->offset = src0 + (dst1 - 0.5f) * scale; + xform->offset = src0 + ((double)dst1 - 0.5) * scale; } }