i965/nir/vec4: Implement linear interpolation

[mesa.git] / src / mesa / drivers / dri / i965 / brw_util.h

diff --git a/src/mesa/drivers/dri/i965/brw_util.h b/src/mesa/drivers/dri/i965/brw_util.h
index 671d72e1cc71af3fb725c24893c68f9729f01103..68f4318d37174566f5f7ad5fcb8bbc9bfe1ab4c0 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_util.h
+++ b/src/mesa/drivers/dri/i965/brw_util.h
@@ -41,7 +41,7 @@ extern GLuint brw_translate_blend_factor( GLenum factor );
 extern GLuint brw_translate_blend_equation( GLenum mode );
 extern GLenum brw_fix_xRGB_alpha(GLenum function);
 
-static inline float
+static inline uint32_t
 brw_get_line_width(struct brw_context *brw)
 {
    /* From the OpenGL 4.4 spec:
@@ -50,9 +50,32 @@ brw_get_line_width(struct brw_context *brw)
     * the supplied width to the nearest integer, then clamping it to the
     * implementation-dependent maximum non-antialiased line width."
     */
-   return CLAMP(!brw->ctx.Multisample._Enabled && !brw->ctx.Line.SmoothFlag
-                ? roundf(brw->ctx.Line.Width) : brw->ctx.Line.Width,
-                0.0, brw->ctx.Const.MaxLineWidth);
+   float line_width =
+      CLAMP(!brw->ctx.Multisample._Enabled && !brw->ctx.Line.SmoothFlag
+            ? roundf(brw->ctx.Line.Width) : brw->ctx.Line.Width,
+            0.0f, brw->ctx.Const.MaxLineWidth);
+   uint32_t line_width_u3_7 = U_FIXED(line_width, 7);
+
+   /* Line width of 0 is not allowed when MSAA enabled */
+   if (brw->ctx.Multisample._Enabled) {
+      if (line_width_u3_7 == 0)
+         line_width_u3_7 = 1;
+   } else if (brw->ctx.Line.SmoothFlag && line_width < 1.5f) {
+      /* 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;
+   }
+
+   return line_width_u3_7;
 }
 
 #endif