On 09/09/2015 06:59 AM, Marius Predut wrote:
> On PNV platform, 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 G45: Volume 2:
> 3D/Media,
> 7.3.13.1 Zero-Width (Cosmetic) Line Rasterization section.
>
> This patch follow the same rules as patches fixing the
> https://bugs.freedesktop.org/show_bug.cgi?id=28832
> bug.
>
> v1: Eduardo Lima Mitev: Wrong indentation inside the if clause.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90367
>
> Signed-off-by: Marius Predut <marius.pre...@intel.com>
> ---
> src/mesa/drivers/dri/i915/i915_state.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/i915/i915_state.c
> b/src/mesa/drivers/dri/i915/i915_state.c
> index 4c83073..ebb4e9a 100644
> --- a/src/mesa/drivers/dri/i915/i915_state.c
> +++ b/src/mesa/drivers/dri/i915/i915_state.c
> @@ -599,6 +599,21 @@ i915LineWidth(struct gl_context * ctx, GLfloat widthf)
>
> width = (int) (widthf * 2);
> width = CLAMP(width, 1, 0xf);
> +
> + if (ctx->Line.Width < 1.5 || widthf < 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 G45: Volume 2: 3D/Media,
Eh... Isn't G45 actually i965-class hardware? GEN4.5, right? I don't
see how a GEN4 bspec reference is useful (or correct?) in the GEN3
driver. I think you want "2.8.4.1 Zero-Width (Cosmetic) Line
Rasterization" from volume 1f of the GEN3 docs.
I looked at section 2.8.4.3 Anti-aliased Line Rasterization of volume 1f
of the GEN3 docs that I have. I don't see any mention of this
restriction. Is it documented anywhere?
It also seems like this will affect non-antialised wide lines. Is that
correct?
> + * 7.3.13.1 Zero-Width (Cosmetic) Line Rasterization section
> + */
> + width = 0;
> + }
> lis4 |= width << S4_LINE_WIDTH_SHIFT;
>
> if (lis4 != i915->state.Ctx[I915_CTXREG_LIS4]) {
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