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-rw-r--r--mesalib/src/gallium/auxiliary/util/u_format.c41
-rw-r--r--mesalib/src/gallium/auxiliary/util/u_format.h11
2 files changed, 52 insertions, 0 deletions
diff --git a/mesalib/src/gallium/auxiliary/util/u_format.c b/mesalib/src/gallium/auxiliary/util/u_format.c
index a8aa5719d..9ef3bb53f 100644
--- a/mesalib/src/gallium/auxiliary/util/u_format.c
+++ b/mesalib/src/gallium/auxiliary/util/u_format.c
@@ -208,6 +208,47 @@ util_format_is_supported(enum pipe_format format, unsigned bind)
}
+/**
+ * Calculates the MRD for the depth format. MRD is used in depth bias
+ * for UNORM and unbound depth buffers. When the depth buffer is floating
+ * point, the depth bias calculation does not use the MRD. However, the
+ * default MRD will be 1.0 / ((1 << 24) - 1).
+ */
+double
+util_get_depth_format_mrd(enum pipe_format format)
+{
+ struct util_format_description *format_desc;
+ /*
+ * Depth buffer formats without a depth component OR scenarios
+ * without a bound depth buffer default to D24.
+ */
+ double mrd = 1.0 / ((1 << 24) - 1);
+ unsigned depth_channel;
+
+ format_desc = (struct util_format_description *)
+ util_format_description(format);
+
+ assert(format_desc);
+
+ /*
+ * Some depth formats do not store the depth component in the first
+ * channel, detect the format and adjust the depth channel. Get the
+ * swizzled depth component channel.
+ */
+ depth_channel = format_desc->swizzle[0];
+
+ if (format_desc->channel[depth_channel].type == UTIL_FORMAT_TYPE_UNSIGNED &&
+ format_desc->channel[depth_channel].normalized) {
+ int depth_bits;
+
+ depth_bits = format_desc->channel[depth_channel].size;
+ mrd = 1.0 / ((1ULL << depth_bits) - 1);
+ }
+
+ return mrd;
+}
+
+
void
util_format_read_4f(enum pipe_format format,
float *dst, unsigned dst_stride,
diff --git a/mesalib/src/gallium/auxiliary/util/u_format.h b/mesalib/src/gallium/auxiliary/util/u_format.h
index 84f16d503..dc777c35c 100644
--- a/mesalib/src/gallium/auxiliary/util/u_format.h
+++ b/mesalib/src/gallium/auxiliary/util/u_format.h
@@ -544,6 +544,17 @@ util_format_is_depth_and_stencil(enum pipe_format format)
util_format_has_stencil(desc);
}
+
+/**
+ * Calculates the MRD for the depth format. MRD is used in depth bias
+ * for UNORM and unbound depth buffers. When the depth buffer is floating
+ * point, the depth bias calculation does not use the MRD. However, the
+ * default MRD will be 1.0 / ((1 << 24) - 1).
+ */
+double
+util_get_depth_format_mrd(enum pipe_format format);
+
+
/**
* Return whether this is an RGBA, Z, S, or combined ZS format.
* Useful for initializing pipe_blit_info::mask.