draw,llvmpipe,util: add depth bias calculation for arb_depth_buffer_float

With this patch, the llvmpipe and draw modules will calculate the depth bias
according to floating point depth buffer semantics described in the
arb_depth_buffer_float specification, when the driver has a z buffer bound
with a format type of UTIL_FORMAT_TYPE_FLOAT.

By default, the driver will use the existing UNORM calculation for depth bias.

A new function, draw_set_zs_format, was added to calculate the Minimum
Resolvable Depth value and floating point depth sense for the draw module.

Reviewed-by: Jose Fonseca <[email protected]>
Reviewed-by: Roland Scheidegger <[email protected]>

1 files changed, 4 insertions, 3 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_context.h b/src/gallium/drivers/llvmpipe/lp_context.h
index 106288a6ad3..9ec18e8429e 100644
--- a/src/gallium/drivers/llvmpipe/lp_context.h
+++ b/src/gallium/drivers/llvmpipe/lp_context.h
@@ -124,9 +124,10 @@ struct llvmpipe_context {
    /** A fake frontface output for unfilled primitives */
    int face_slot;
 
-   /**< minimum resolvable depth value, for polygon offset */   
-   double mrd;
-   
+   /** Depth format and bias settings. */
+   boolean floating_point_depth;
+   double mrd;   /**< minimum resolvable depth value, for polygon offset */
+
    /** The tiling engine */
    struct lp_setup_context *setup;
    struct lp_setup_variant setup_variant;