Mesa (gallium-llvmpipe): llvmpipe: comments about blend generator

Brian Paul brianp at kemper.freedesktop.org
Wed Aug 19 19:19:30 UTC 2009


Module: Mesa
Branch: gallium-llvmpipe
Commit: f03ef54d195132e3d28fb03df7809112d7366598
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f03ef54d195132e3d28fb03df7809112d7366598

Author: Brian Paul <brianp at vmware.com>
Date:   Wed Aug 19 13:14:15 2009 -0600

llvmpipe: comments about blend generator

---

 src/gallium/drivers/llvmpipe/lp_state_blend.c |   16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/gallium/drivers/llvmpipe/lp_state_blend.c b/src/gallium/drivers/llvmpipe/lp_state_blend.c
index d1c8536..d0cdcd8 100644
--- a/src/gallium/drivers/llvmpipe/lp_state_blend.c
+++ b/src/gallium/drivers/llvmpipe/lp_state_blend.c
@@ -45,6 +45,12 @@
 #include "lp_bld_debug.h"
 
 
+/**
+ * Generate blending code according to blend->base state.
+ * The blend function will look like:
+ *    blend(mask, src_color, constant color, dst_color)
+ * dst_color will be modified and contain the result of the blend func.
+ */
 static void
 blend_generate(struct llvmpipe_screen *screen,
                struct lp_blend_state *blend)
@@ -69,11 +75,11 @@ blend_generate(struct llvmpipe_screen *screen,
    unsigned i;
 
    type.value = 0;
-   type.floating = FALSE;
-   type.sign = FALSE;
-   type.norm = TRUE;
-   type.width = 8;
-   type.length = 16;
+   type.floating = FALSE; /* values are integers */
+   type.sign = FALSE;     /* values are unsigned */
+   type.norm = TRUE;      /* values are in [0,1] or [-1,1] */
+   type.width = 8;        /* 8-bit ubyte values */
+   type.length = 16;      /* 16 elements per vector */
 
    vec_type = lp_build_vec_type(type);
    int_vec_type = lp_build_int_vec_type(type);




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