1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173

#![allow(bad_style)]

mod ffi;

use std::os::raw::*;
use std::mem;
use std::ptr;

/// Rust FFI for the MikkTSpace implementation.
const INTERFACE: ffi::SMikkTSpaceInterface = ffi::SMikkTSpaceInterface {
    m_getNumFaces: faces,
    m_getNumVerticesOfFace: vertices,
    m_getPosition: position,
    m_getNormal: normal,
    m_getTexCoord: tex_coord,
    m_setTSpaceBasic: set_tspace_basic,
    m_setTSpace: set_tspace,
};

/// Rust front-end API for tangent generation.
struct Closures<'a> {
    /// Returns the number of vertices per face.
    pub vertices_per_face: &'a Fn() -> usize,
    
    /// Returns the number of faces.
    pub face_count: &'a Fn() -> usize,
    
    /// Returns the positions of the indexed face.
    pub position: &'a Fn(usize, usize) -> &'a [f32; 3],

    /// Returns the normals of the indexed face.
    pub normal: &'a Fn(usize, usize) -> &'a [f32; 3],

    /// Returns the texture co-ordinates of the indexed face.
    pub tex_coord: &'a Fn(usize, usize) -> &'a [f32; 2],

    /// Sets the generated tangent for the indexed face.
    pub set_tangent: &'a mut FnMut(usize, usize, [f32; 4]),
}

/// Returns the number of faces (triangles/quads) on the mesh to be processed.
extern "C" fn faces(pContext: *const ffi::SMikkTSpaceContext) -> c_int {
    unsafe {
        let x = (*pContext).m_pUserData as *const Closures;
        ((*x).face_count)() as c_int
    }
}

/// Returns the number of vertices on face number iFace
/// iFace is a number in the range {0, 1, ..., getNumFaces()-1}
extern "C" fn vertices(
    pContext: *const ffi::SMikkTSpaceContext,
    _iFace: c_int,
) -> c_int {
    unsafe {
        let x = (*pContext).m_pUserData as *const Closures;
        ((*x).vertices_per_face)() as c_int
    }
}

/// Returns the position of the referenced face of vertex number
/// iVert, in the range {0,1,2} for triangles, and {0,1,2,3} for quads.
extern "C" fn position(
    pContext: *const ffi::SMikkTSpaceContext,
    fvPosOut: *mut c_float,
    iFace: c_int,
    iVert: c_int,
) {
    unsafe {
        let x = (*pContext).m_pUserData as *const Closures;
        let slice = ((*x).position)(iFace as usize, iVert as usize);
        let src = slice.as_ptr() as *const c_float;
        ptr::copy_nonoverlapping::<c_float>(src, fvPosOut, 3);
    }
}

/// Returns the normal of the referenced face of vertex number
/// iVert, in the range {0,1,2} for triangles, and {0,1,2,3} for quads.
extern "C" fn normal(
    pContext: *const ffi::SMikkTSpaceContext,
    fvNormOut: *mut c_float,
    iFace: c_int,
    iVert: c_int,
) {
    unsafe {
        let x = (*pContext).m_pUserData as *const Closures;
        let slice = ((*x).normal)(iFace as usize, iVert as usize);
        let src = slice.as_ptr() as *const c_float;
        ptr::copy_nonoverlapping::<c_float>(src, fvNormOut, 3);
    }
}

/// Returns the texcoord of the referenced face of vertex number
/// iVert, in the range {0,1,2} for triangles, and {0,1,2,3} for quads.
extern "C" fn tex_coord(
    pContext: *const ffi::SMikkTSpaceContext,
    fvTexcOut: *mut c_float,
    iFace: c_int,
    iVert: c_int,
) {
    unsafe {
        let x = (*pContext).m_pUserData as *const Closures;
        let slice = ((*x).tex_coord)(iFace as usize, iVert as usize);
        let src = slice.as_ptr() as *const c_float;
        ptr::copy_nonoverlapping::<c_float>(src, fvTexcOut, 2);
    }
}

/// Returns the tangent and its sign to the application.
extern "C" fn set_tspace_basic(
    pContext: *mut ffi::SMikkTSpaceContext,
    fvTangent: *const c_float,
    fSign: c_float,
    iFace: c_int,
    iVert: c_int,
) {
    unsafe {
        let x = (*pContext).m_pUserData as *mut Closures;
        let mut tangent: [f32; 4] = mem::uninitialized();
        let dst: *mut c_float = tangent.as_mut_ptr();
        ptr::copy_nonoverlapping::<c_float>(fvTangent, dst, 3);
        tangent[3] = fSign;
        ((*x).set_tangent)(iFace as usize, iVert as usize, tangent);
    }
}

/// Returns tangent space results to the application.
extern "C" fn set_tspace(
    pContext: *mut ffi::SMikkTSpaceContext,
    fvTangent: *const c_float,
    _fvBiTangent: *const c_float,
    _fMagS: c_float,
    _fMagT: c_float,
    bIsOrientationPreserving: ffi::tbool,
    iFace: c_int,
    iVert: c_int,
) {
    let fSign = if bIsOrientationPreserving != 0 { 1.0 } else { -1.0 };
    set_tspace_basic(pContext, fvTangent, fSign, iFace, iVert);
}

impl<'a> Closures<'a> {
    /// Generates tangents.
    pub fn generate(mut self) -> bool {
        let ctx = ffi::SMikkTSpaceContext {
            m_pInterface: &INTERFACE,
            m_pUserData: &mut self as *mut Closures as *mut c_void,
        };
        unsafe {
            ffi::genTangSpaceDefault(&ctx) == ffi::TTRUE
        }
    }
}

/// Generates tangents.
pub fn generate_tangents<'a>(
    vertices_per_face: &'a Fn() -> usize,
    face_count: &'a Fn() -> usize,
    position: &'a Fn(usize, usize) -> &'a [f32; 3],
    normal: &'a Fn(usize, usize) -> &'a [f32; 3],
    tex_coord: &'a Fn(usize, usize) -> &'a [f32; 2],
    set_tangent: &'a mut FnMut(usize, usize, [f32; 4]),
) -> bool {
    let closures = Closures {
        vertices_per_face,
        face_count,
        position,
        normal,
        tex_coord,
        set_tangent,
    };
    closures.generate()
}