swrast: fix span color type selection

Fixes a regression from commit 660ed923ded3552e023ef8c3dd9f92e6792f1bd2.
The basic idea is to look at the format of the dest renderbuffer and
choose either GLubyte or GLfloat for colors.  The previous code used
_mesa_format_to_type_and_comps() which could return a bunch types other
than ubyte/float.

Determine the datatype at renderbuffer mapping time to avoid frequent
calls to the format query functions.

NOTE: This is a candidate for the 8.0 branch.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=45578
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=45577

1 files changed, 26 insertions, 2 deletions

diff --git a/src/mesa/swrast/s_renderbuffer.c b/src/mesa/swrast/s_renderbuffer.c
index 637a7b6dc1e..d8a7467b08d 100644
--- a/src/mesa/swrast/s_renderbuffer.c
+++ b/src/mesa/swrast/s_renderbuffer.c
@@ -615,8 +615,31 @@ unmap_attachment(struct gl_context *ctx,
 
    srb->Map = NULL;
 }
- 
- 
+
+
+/**
+ * Determine what type to use (ubyte vs. float) for span colors for the
+ * given renderbuffer.
+ * See also _swrast_write_rgba_span().
+ */
+static void
+find_renderbuffer_colortype(struct gl_renderbuffer *rb)
+{
+   struct swrast_renderbuffer *srb = swrast_renderbuffer(rb);
+   GLuint rbMaxBits = _mesa_get_format_max_bits(rb->Format);
+   GLenum rbDatatype = _mesa_get_format_datatype(rb->Format);
+
+   if (rbDatatype == GL_UNSIGNED_NORMALIZED && rbMaxBits <= 8) {
+      /* the buffer's values fit in GLubyte values */
+      srb->ColorType = GL_UNSIGNED_BYTE;
+   }
+   else {
+      /* use floats otherwise */
+      srb->ColorType = GL_FLOAT;
+   }
+}
+
+
 /**
  * Map the renderbuffers we'll use for tri/line/point rendering.
  */
@@ -641,6 +664,7 @@ _swrast_map_renderbuffers(struct gl_context *ctx)
 
    for (buf = 0; buf < fb->_NumColorDrawBuffers; buf++) {
       map_attachment(ctx, fb, fb->_ColorDrawBufferIndexes[buf]);
+      find_renderbuffer_colortype(fb->_ColorDrawBuffers[buf]);
    }
 }