From a9b04d8a0d96922a49ac7eb1b91b3a376a959f64 Mon Sep 17 00:00:00 2001 From: Marius Predut Date: Thu, 23 Apr 2015 18:41:14 +0300 Subject: [PATCH] i965/aa: fixing anti-aliasing bug for thinnest width lines - GEN6 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit On SNB and IVB hw, for 1 pixel line thickness or less, the general anti-aliasing algorithm give up - garbage line is generated. Setting a Line Width of 0.0 specifies the rasterization of the “thinnest” (one-pixel-wide), non-antialiased lines. Lines rendered with zero Line Width are rasterized using Grid Intersection Quantization rules as specified by bspec section 6.3.12.1 Zero-Width (Cosmetic) Line Rasterization. v2: Daniel Stone: Fix = used instead of == in an if-statement. v3: Ian Romanick: Use "._Enabled" flag insteed ".Enabled". Add code comments. re-word wrap the commit message. Add a complete bugzillia list. Improve the hardcoded values to produce better results. v4: Matt Turner: typo fixes and adjust <= 1.49 to become < 1.5 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=28832 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=9951 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=27007 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=60797 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=15006 Acked-by: Chris Forbes Acked-by: Kenneth Graunke Signed-off-by: Marius Predut --- src/mesa/drivers/dri/i965/gen6_sf_state.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/src/mesa/drivers/dri/i965/gen6_sf_state.c b/src/mesa/drivers/dri/i965/gen6_sf_state.c index ea5c47a895f..e445ce25600 100644 --- a/src/mesa/drivers/dri/i965/gen6_sf_state.c +++ b/src/mesa/drivers/dri/i965/gen6_sf_state.c @@ -367,9 +367,25 @@ upload_sf_state(struct brw_context *brw) float line_width = roundf(CLAMP(ctx->Line.Width, 0.0, ctx->Const.MaxLineWidth)); uint32_t line_width_u3_7 = U_FIXED(line_width, 7); - /* TODO: line width of 0 is not allowed when MSAA enabled */ - if (line_width_u3_7 == 0) - line_width_u3_7 = 1; + + /* Line width of 0 is not allowed when MSAA enabled */ + if (ctx->Multisample._Enabled) { + if (line_width_u3_7 == 0) + line_width_u3_7 = 1; + } else if (ctx->Line.SmoothFlag && ctx->Line.Width < 1.5) { + /* For 1 pixel line thickness or less, the general + * anti-aliasing algorithm gives up, and a garbage line is + * generated. Setting a Line Width of 0.0 specifies the + * rasterization of the "thinnest" (one-pixel-wide), + * non-antialiased lines. + * + * Lines rendered with zero Line Width are rasterized using + * Grid Intersection Quantization rules as specified by + * bspec section 6.3.12.1 Zero-Width (Cosmetic) Line + * Rasterization. + */ + line_width_u3_7 = 0; + } dw3 |= line_width_u3_7 << GEN6_SF_LINE_WIDTH_SHIFT; } if (ctx->Line.SmoothFlag) { -- 2.30.2