1 files changed, 70 insertions, 0 deletions
diff --git a/intern/gawain/src/gwn_attr_binding.c b/intern/gawain/src/gwn_attr_binding.c
new file mode 100644
index 00000000000..7647a927b1e
--- /dev/null
+++ b/intern/gawain/src/gwn_attr_binding.c
@@ -0,0 +1,70 @@
+
+// Gawain vertex attribute binding
+//
+// This code is part of the Gawain library, with modifications
+// specific to integration with Blender.
+//
+// Copyright 2016 Mike Erwin
+//
+// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of
+// the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+#include "gwn_attr_binding.h"
+#include "gwn_attr_binding_private.h"
+#include <stddef.h>
+
+#if GWN_VERT_ATTR_MAX_LEN != 16
+  #error "attrib binding code assumes GWN_VERT_ATTR_MAX_LEN = 16"
+#endif
+
+void AttribBinding_clear(Gwn_AttrBinding* binding)
+	{
+	binding->loc_bits = 0;
+	binding->enabled_bits = 0;
+	}
+
+unsigned read_attrib_location(const Gwn_AttrBinding* binding, unsigned a_idx)
+	{
+#if TRUST_NO_ONE
+	assert(a_idx < GWN_VERT_ATTR_MAX_LEN);
+	assert(binding->enabled_bits & (1 << a_idx));
+#endif
+
+	return (binding->loc_bits >> (4 * a_idx)) & 0xF;
+	}
+
+static void write_attrib_location(Gwn_AttrBinding* binding, unsigned a_idx, unsigned location)
+	{
+#if TRUST_NO_ONE
+	assert(a_idx < GWN_VERT_ATTR_MAX_LEN);
+	assert(location < GWN_VERT_ATTR_MAX_LEN);
+#endif
+
+	const unsigned shift = 4 * a_idx;
+	const uint64_t mask = ((uint64_t)0xF) << shift;
+	// overwrite this attrib's previous location
+	binding->loc_bits = (binding->loc_bits & ~mask) | (location << shift);
+	// mark this attrib as enabled
+	binding->enabled_bits |= 1 << a_idx;
+	}
+
+void get_attrib_locations(const Gwn_VertFormat* format, Gwn_AttrBinding* binding, const Gwn_ShaderInterface* shaderface)
+	{
+	AttribBinding_clear(binding);
+
+	for (unsigned a_idx = 0; a_idx < format->attrib_ct; ++a_idx)
+		{
+		const Gwn_VertAttr* a = format->attribs + a_idx;
+		for (unsigned n_idx = 0; n_idx < a->name_ct; ++n_idx)
+			{
+			const Gwn_ShaderInput* input = GWN_shaderinterface_attr(shaderface, a->name[n_idx]);
+
+#if TRUST_NO_ONE
+			assert(input != NULL);
+			// TODO: make this a recoverable runtime error? indicates mismatch between vertex format and program
+#endif
+
+			write_attrib_location(binding, a_idx, input->location);
+			}
+		}
+	}