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authorBrian <brian.paul@tungstengraphics.com>2007-09-18 12:50:20 -0600
committerBrian <brian.paul@tungstengraphics.com>2007-09-18 12:56:22 -0600
commit72b0a57cfa99e55ad6e1b4ddcd486c202ee1f22d (patch)
tree36948381056de902126b17ea6c5e892bd794d7ce /src
parentccd63b54cfbb6bb241d55f7ac95afcd14819f469 (diff)
additional comments for tri_persp_coeff()
Diffstat (limited to 'src')
-rw-r--r--src/mesa/pipe/softpipe/sp_prim_setup.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/src/mesa/pipe/softpipe/sp_prim_setup.c b/src/mesa/pipe/softpipe/sp_prim_setup.c
index c64a4e9708..d0baf0734b 100644
--- a/src/mesa/pipe/softpipe/sp_prim_setup.c
+++ b/src/mesa/pipe/softpipe/sp_prim_setup.c
@@ -428,6 +428,10 @@ static void tri_linear_coeff( struct setup_stage *setup,
/**
* Compute a0, dadx and dady for a perspective-corrected interpolant,
* for a triangle.
+ * We basically multiply the vertex value by 1/w before computing
+ * the plane coefficients (a0, dadx, dady).
+ * Later, when we compute the value at a particular fragment position we'll
+ * divide the interpolated value by the interpolated W at that fragment.
*/
static void tri_persp_coeff( struct setup_stage *setup,
unsigned slot,