70 lines
1.8 KiB
C
70 lines
1.8 KiB
C
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// Gawain vertex attribute binding
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//
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// This code is part of the Gawain library, with modifications
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// specific to integration with Blender.
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//
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// Copyright 2016 Mike Erwin
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//
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// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of
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// the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
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#include "attrib_binding.h"
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#if MAX_VERTEX_ATTRIBS != 16
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#error "attrib binding code assumes MAX_VERTEX_ATTRIBS = 16"
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#endif
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void clear_AttribBinding(AttribBinding* binding)
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{
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binding->loc_bits = 0;
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binding->enabled_bits = 0;
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}
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unsigned read_attrib_location(const AttribBinding* binding, unsigned a_idx)
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{
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#if TRUST_NO_ONE
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assert(a_idx < MAX_VERTEX_ATTRIBS);
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assert(binding->enabled_bits & (1 << a_idx));
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#endif
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return (binding->loc_bits >> (4 * a_idx)) & 0xF;
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}
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static void write_attrib_location(AttribBinding* binding, unsigned a_idx, unsigned location)
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{
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#if TRUST_NO_ONE
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assert(a_idx < MAX_VERTEX_ATTRIBS);
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assert(location < MAX_VERTEX_ATTRIBS);
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#endif
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const unsigned shift = 4 * a_idx;
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const uint64_t mask = ((uint64_t)0xF) << shift;
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// overwrite this attrib's previous location
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binding->loc_bits = (binding->loc_bits & ~mask) | (location << shift);
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// mark this attrib as enabled
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binding->enabled_bits |= 1 << a_idx;
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}
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void get_attrib_locations(const VertexFormat* format, AttribBinding* binding, GLuint program)
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{
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#if TRUST_NO_ONE
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assert(glIsProgram(program));
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#endif
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clear_AttribBinding(binding);
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for (unsigned a_idx = 0; a_idx < format->attrib_ct; ++a_idx)
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{
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const Attrib* a = format->attribs + a_idx;
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GLint loc = glGetAttribLocation(program, a->name);
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#if TRUST_NO_ONE
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assert(loc != -1);
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// TODO: make this a recoverable runtime error? indicates mismatch between vertex format and program
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#endif
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write_attrib_location(binding, a_idx, loc);
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}
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}
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