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/*
Copyright 2022 Marc Sunet
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CGLTF_TANGENTS_H_INCLUDED__
#define CGLTF_TANGENTS_H_INCLUDED__
#include <cgltf.h>
/// A buffer that holds tangent vectors.
///
/// Tangent vectors are tightly packed in the array.
///
/// Tangent vectors have 4 coordinates: (X,Y,Z) for the vector, W for the sign.
/// The usual rules of MikkTSpace apply, namely that the bitangent should be
/// computed as:
///
/// bitangent = tangent.w * cross(normal, tangent.xyz);
///
/// Refer to the MikkTSpace documentation for more details.
///
/// The primitive pointer points to the mesh primitive for which the tangents in
/// this buffer were computed. When your application loads mesh primitives, it
/// can scan the cgltfTangetBuffer array outputed by cgltf_compute_tangents() to
/// see whether tangents were computed for the mesh primitive.
typedef struct cgltfTangentBuffer {
void* data; // X-coordinate of the first tangent vector.
cgltf_size size_bytes; // Total Size of data in bytes.
cgltf_primitive* primitive; // The primitive these tangents belong to.
} cgltfTangentBuffer;
/// Compute tangent vectors for normal-mapped mesh primitives missing them.
///
/// cgltf_options can be zeroed out but must be non-null.
///
/// cgltf_data is the scene previously loaded by cgltf.
///
/// out_tangent_buffers is an output array of tangent buffers, one buffer per
/// mesh primitive for which tangents were computed.
///
/// out_num_tangent_buffers is the number of tangent buffers in the output
/// array.
cgltf_result cgltf_compute_tangents(const cgltf_options*, const cgltf_data*,
cgltfTangentBuffer** out_tangent_buffers,
cgltf_size* out_num_tangent_buffers);
#endif // CGLTF_TANGENTS_H_INCLUDED__
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