1 /// Custom sized 2-dimension Matrices
2 module gfm.math.matrix;
3 
4 import std.math,
5        std.typetuple,
6        std.traits,
7        std..string,
8        std.typecons,
9        std.conv;
10 
11 import gfm.math.vector,
12        gfm.math.shapes,
13        gfm.math.quaternion;
14 
15 /// Generic non-resizeable matrix with R rows and C columns.
16 /// Intended for 3D use (size 3x3 and 4x4).
17 /// Important: <b>Matrices here are in row-major order whereas OpenGL is column-major.</b>
18 /// Params:
19 ///   T = type of elements
20 ///   R = number of rows
21 ///   C = number of columns
22 struct Matrix(T, int R, int C)
23 {
24     public
25     {
26         static assert(R >= 1 && C >= 1);
27 
28         alias Vector!(T, C) row_t;
29         alias Vector!(T, R) column_t;
30 
31         enum bool isSquare = (R == C);
32 
33         // fields definition
34         union
35         {
36             T[C*R] v;        // all elements
37             row_t[R] rows;   // all rows
38             T[C][R] c;       // components
39         }
40 
41         @nogc this(U...)(U values) pure nothrow
42         {
43             static if ((U.length == C*R) && allSatisfy!(isTAssignable, U))
44             {
45                 // construct with components
46                 foreach(int i, x; values)
47                     v[i] = x;
48             }
49             else static if ((U.length == 1) && (isAssignable!(U[0])) && (!is(U[0] : Matrix)))
50             {
51                 // construct with assignment
52                 opAssign!(U[0])(values[0]);
53             }
54             else static assert(false, "cannot create a matrix from given arguments");
55         }
56 
57         /// Construct a matrix from columns.
58         @nogc static Matrix fromColumns(column_t[] columns) pure nothrow
59         {
60             assert(columns.length == C);
61             Matrix res;
62             for (int i = 0; i < R; ++i)
63                 for (int j = 0; j < C; ++j)
64                 {
65                    res.c[i][j] = columns[j][i];
66                 }
67             return res;
68         }
69 
70         /// Construct a matrix from rows.
71         @nogc static Matrix fromRows(row_t[] rows) pure nothrow
72         {
73             assert(rows.length == R);
74             Matrix res;
75             res.rows[] = rows[];
76             return res;
77         }
78 
79         /// Construct matrix with a scalar.
80         @nogc this(U)(T x) pure nothrow
81         {
82             for (int i = 0; i < _N; ++i)
83                 v[i] = x;
84         }
85 
86         /// Assign with a scalar.
87         @nogc ref Matrix opAssign(U : T)(U x) pure nothrow
88         {
89             for (int i = 0; i < R * C; ++i)
90                 v[i] = x;
91             return this;
92         }
93 
94         /// Assign with a samey matrice.
95         @nogc ref Matrix opAssign(U : Matrix)(U x) pure nothrow
96         {
97             for (int i = 0; i < R * C; ++i)
98                 v[i] = x.v[i];
99             return this;
100         }
101 
102         /// Assign from other small matrices (same size, compatible type).
103         @nogc ref Matrix opAssign(U)(U x) pure nothrow
104             if (isMatrixInstantiation!U
105                 && is(U._T : _T)
106                 && (!is(U: Matrix))
107                 && (U._R == R) && (U._C == C))
108         {
109             for (int i = 0; i < R * C; ++i)
110                 v[i] = x.v[i];
111             return this;
112         }
113 
114         /// Assign with a static array of size R * C.
115         @nogc ref Matrix opAssign(U)(U x) pure nothrow
116             if ((isStaticArray!U)
117                 && is(typeof(x[0]) : T)
118                 && (U.length == R * C))
119         {
120             for (int i = 0; i < R * C; ++i)
121                 v[i] = x[i];
122             return this;
123         }
124 
125         /// Assign with a dynamic array of size R * C.
126         @nogc ref Matrix opAssign(U)(U x) pure nothrow
127             if ((isDynamicArray!U)
128                 && is(typeof(x[0]) : T))
129         {
130             assert(x.length == R * C);
131             for (int i = 0; i < R * C; ++i)
132                 v[i] = x[i];
133             return this;
134         }
135 
136         /// Return a pointer to content.
137         @nogc inout(T)* ptr() pure inout nothrow @property
138         {
139             return v.ptr;
140         }
141 
142         /// Returns a column as a vector
143         /// Returns: column j as a vector.
144         @nogc column_t column(int j) pure const nothrow
145         {
146             column_t res = void;
147             for (int i = 0; i < R; ++i)
148                 res.v[i] = c[i][j];
149             return res;
150         }
151 
152         /// Returns a row as a vector
153         /// Returns: row i as a vector.
154         @nogc row_t row(int i) pure const nothrow
155         {
156             return rows[i];
157         }
158 
159         /// Covnerts to pretty string.
160         string toString() const nothrow
161         {
162             try
163                 return format("%s", v);
164             catch (Exception e)
165                 assert(false); // should not happen since format is right
166         }
167 
168         /// Matrix * scalar multiplication.
169         @nogc Matrix opBinary(string op)(T factor) pure const nothrow if (op == "*")
170         {
171             Matrix result = void;
172 
173             for (int i = 0; i < R; ++i)
174             {
175                 for (int j = 0; j < C; ++j)
176                 {
177                     result.c[i][j] = c[i][j] * factor;
178                 }
179             }
180             return result;
181         }
182 
183         /// Matrix * vector multiplication.
184         @nogc column_t opBinary(string op)(row_t x) pure const nothrow if (op == "*")
185         {
186             column_t res = void;
187             for (int i = 0; i < R; ++i)
188             {
189                 T sum = 0;
190                 for (int j = 0; j < C; ++j)
191                 {
192                     sum += c[i][j] * x.v[j];
193                 }
194                 res.v[i] = sum;
195             }
196             return res;
197         }
198 
199         /// Matrix * matrix multiplication.
200         @nogc auto opBinary(string op, U)(U x) pure const nothrow
201             if (isMatrixInstantiation!U && (U._R == C) && (op == "*"))
202         {
203             Matrix!(T, R, U._C) result = void;
204 
205             for (int i = 0; i < R; ++i)
206             {
207                 for (int j = 0; j < U._C; ++j)
208                 {
209                     T sum = 0;
210                     for (int k = 0; k < C; ++k)
211                         sum += c[i][k] * x.c[k][j];
212                     result.c[i][j] = sum;
213                 }
214             }
215             return result;
216         }
217 
218         /// Matrix add and substraction.
219         @nogc Matrix opBinary(string op, U)(U other) pure const nothrow
220             if (is(U : Matrix) && (op == "+" || op == "-"))
221         {
222             Matrix result = void;
223 
224             for (int i = 0; i < R; ++i)
225             {
226                 for (int j = 0; j < C; ++j)
227                 {
228                     mixin("result.c[i][j] = c[i][j] " ~ op ~ " other.c[i][j];");
229                 }
230             }
231             return result;
232         }
233 
234         // matrix *= scalar
235         @nogc ref Matrix opOpAssign(string op, U : T)(U x) pure nothrow if (op == "*")
236         {
237             for (int i = 0; i < R * C; ++i)
238                 v[i] *= x;
239             return this;
240         }
241 
242         /// Assignment operator with another samey matrix.
243         @nogc ref Matrix opOpAssign(string op, U)(U operand) pure nothrow 
244             if (is(U : Matrix) && (op == "*" || op == "+" || op == "-"))
245         {
246             mixin("Matrix result = this " ~ op ~ " operand;");
247             return opAssign!Matrix(result);
248         }
249 
250         /// Matrix += <something convertible to a Matrix>
251         /// Matrix -= <something convertible to a Matrix>
252         @nogc ref Matrix opOpAssign(string op, U)(U operand) pure nothrow 
253             if ((isConvertible!U) && (op == "*" || op == "+" || op == "-"))
254         {
255             Matrix conv = operand;
256             return opOpAssign!op(conv);
257         }
258 
259         /// Cast to other matrix types.
260         /// If the size are different, the resulting matrix is truncated
261         /// and/or filled with identity coefficients.
262         @nogc U opCast(U)() pure const nothrow if (isMatrixInstantiation!U)
263         {
264             U res = U.identity();
265             enum minR = R < U._R ? R : U._R;
266             enum minC = C < U._C ? C : U._C;
267             for (int i = 0; i < minR; ++i)
268                 for (int j = 0; j < minC; ++j)
269                 {
270                     res.c[i][j] = cast(U._T)(c[i][j]);
271                 }
272             return res;
273         }
274 
275         @nogc bool opEquals(U)(U other) pure const nothrow if (is(U : Matrix))
276         {
277             for (int i = 0; i < R * C; ++i)
278                 if (v[i] != other.v[i])
279                     return false;
280             return true;
281         }
282 
283         @nogc bool opEquals(U)(U other) pure const nothrow
284             if ((isAssignable!U) && (!is(U: Matrix)))
285         {
286             Matrix conv = other;
287             return opEquals(conv);
288         }
289 
290         // +matrix, -matrix, ~matrix, !matrix
291         @nogc Matrix opUnary(string op)() pure const nothrow if (op == "+" || op == "-" || op == "~" || op == "!")
292         {
293             Matrix res = void;
294             for (int i = 0; i < N; ++i)
295                 mixin("res.v[i] = " ~ op ~ "v[i];");
296             return res;
297         }
298 
299         /// Convert 3x3 rotation matrix to quaternion.
300         /// See_also: 3D Math Primer for Graphics and Game Development.
301         @nogc U opCast(U)() pure const nothrow if (isQuaternionInstantiation!U
302                                                    && is(U._T : _T)
303                                                    && (_R == 3) && (_C == 3))
304         {
305             T fourXSquaredMinus1 = c[0][0] - c[1][1] - c[2][2];
306             T fourYSquaredMinus1 = c[1][1] - c[0][0] - c[2][2];
307             T fourZSquaredMinus1 = c[2][2] - c[0][0] - c[1][1];
308             T fourWSquaredMinus1 = c[0][0] + c[1][1] + c[2][2];
309 
310             int biggestIndex = 0;
311             T fourBiggestSquaredMinus1 = fourWSquaredMinus1;
312 
313             if(fourXSquaredMinus1 > fourBiggestSquaredMinus1)
314             {
315                 fourBiggestSquaredMinus1 = fourXSquaredMinus1;
316                 biggestIndex = 1;
317             }
318 
319             if(fourYSquaredMinus1 > fourBiggestSquaredMinus1)
320             {
321                 fourBiggestSquaredMinus1 = fourYSquaredMinus1;
322                 biggestIndex = 2;
323             }
324 
325             if(fourZSquaredMinus1 > fourBiggestSquaredMinus1)
326             {
327                 fourBiggestSquaredMinus1 = fourZSquaredMinus1;
328                 biggestIndex = 3;
329             }
330 
331             T biggestVal = sqrt(fourBiggestSquaredMinus1 + 1) / 2;
332             T mult = 1 / (biggestVal * 4);
333 
334             U quat;
335             switch(biggestIndex)
336             {
337                 case 1:
338                     quat.w = (c[1][2] - c[2][1]) * mult;
339                     quat.x = biggestVal;
340                     quat.y = (c[0][1] + c[1][0]) * mult;
341                     quat.z = (c[2][0] + c[0][2]) * mult;
342                     break;
343 
344                 case 2:
345                     quat.w = (c[2][0] - c[0][2]) * mult;
346                     quat.x = (c[0][1] + c[1][0]) * mult;
347                     quat.y = biggestVal;
348                     quat.z = (c[1][2] + c[2][1]) * mult;
349                     break;
350 
351                 case 3:
352                     quat.w = (c[0][1] - c[1][0]) * mult;
353                     quat.x = (c[2][0] + c[0][2]) * mult;
354                     quat.y = (c[1][2] + c[2][1]) * mult;
355                     quat.z = biggestVal;
356                     break;
357 
358                 default: // biggestIndex == 0
359                     quat.w = biggestVal;
360                     quat.x = (c[1][2] - c[2][1]) * mult;
361                     quat.y = (c[2][0] - c[0][2]) * mult;
362                     quat.z = (c[0][1] - c[1][0]) * mult;
363                     break;
364             }
365 
366             return quat;
367         }
368 
369         /// Converts a 4x4 rotation matrix to quaternion.
370         @nogc U opCast(U)() pure const nothrow if (isQuaternionInstantiation!U
371                                                    && is(U._T : _T)
372                                                    && (_R == 4) && (_C == 4))
373         {
374             auto m3 = cast(mat3!T)(this);
375             return cast(U)(m3);
376         }
377 
378         static if (isSquare && isFloatingPoint!T && R == 1)
379         {
380             /// Returns an inverted copy of this matrix
381             /// Returns: inverse of matrix.
382             /// Note: Matrix inversion is provided for 1x1, 2x2, 3x3 and 4x4 floating point matrices.
383             @nogc Matrix inverse() pure const nothrow
384             {
385                 return Matrix( 1 / c[0][0]);
386             }
387         }
388 
389         static if (isSquare && isFloatingPoint!T && R == 2)
390         {
391             /// Returns an inverted copy of this matrix
392             /// Returns: inverse of matrix.
393             /// Note: Matrix inversion is provided for 1x1, 2x2, 3x3 and 4x4 floating point matrices.
394             @nogc Matrix inverse() pure const nothrow
395             {
396                 T invDet = 1 / (c[0][0] * c[1][1] - c[0][1] * c[1][0]);
397                 return Matrix( c[1][1] * invDet, -c[0][1] * invDet,
398                                    -c[1][0] * invDet,  c[0][0] * invDet);
399             }
400         }
401 
402         static if (isSquare && isFloatingPoint!T && R == 3)
403         {
404             /// Returns an inverted copy of this matrix
405             /// Returns: inverse of matrix.
406             /// Note: Matrix inversion is provided for 1x1, 2x2, 3x3 and 4x4 floating point matrices.
407             @nogc Matrix inverse() pure const nothrow
408             {
409                 T det = c[0][0] * (c[1][1] * c[2][2] - c[2][1] * c[1][2])
410                       - c[0][1] * (c[1][0] * c[2][2] - c[1][2] * c[2][0])
411                       + c[0][2] * (c[1][0] * c[2][1] - c[1][1] * c[2][0]);
412                 T invDet = 1 / det;
413 
414                 Matrix res = void;
415                 res.c[0][0] =  (c[1][1] * c[2][2] - c[2][1] * c[1][2]) * invDet;
416                 res.c[0][1] = -(c[0][1] * c[2][2] - c[0][2] * c[2][1]) * invDet;
417                 res.c[0][2] =  (c[0][1] * c[1][2] - c[0][2] * c[1][1]) * invDet;
418                 res.c[1][0] = -(c[1][0] * c[2][2] - c[1][2] * c[2][0]) * invDet;
419                 res.c[1][1] =  (c[0][0] * c[2][2] - c[0][2] * c[2][0]) * invDet;
420                 res.c[1][2] = -(c[0][0] * c[1][2] - c[1][0] * c[0][2]) * invDet;
421                 res.c[2][0] =  (c[1][0] * c[2][1] - c[2][0] * c[1][1]) * invDet;
422                 res.c[2][1] = -(c[0][0] * c[2][1] - c[2][0] * c[0][1]) * invDet;
423                 res.c[2][2] =  (c[0][0] * c[1][1] - c[1][0] * c[0][1]) * invDet;
424                 return res;
425             }
426         }
427 
428         static if (isSquare && isFloatingPoint!T && R == 4)
429         {
430             /// Returns an inverted copy of this matrix
431             /// Returns: inverse of matrix.
432             /// Note: Matrix inversion is provided for 1x1, 2x2, 3x3 and 4x4 floating point matrices.
433             @nogc Matrix inverse() pure const nothrow
434             {
435                 T det2_01_01 = c[0][0] * c[1][1] - c[0][1] * c[1][0];
436                 T det2_01_02 = c[0][0] * c[1][2] - c[0][2] * c[1][0];
437                 T det2_01_03 = c[0][0] * c[1][3] - c[0][3] * c[1][0];
438                 T det2_01_12 = c[0][1] * c[1][2] - c[0][2] * c[1][1];
439                 T det2_01_13 = c[0][1] * c[1][3] - c[0][3] * c[1][1];
440                 T det2_01_23 = c[0][2] * c[1][3] - c[0][3] * c[1][2];
441 
442                 T det3_201_012 = c[2][0] * det2_01_12 - c[2][1] * det2_01_02 + c[2][2] * det2_01_01;
443                 T det3_201_013 = c[2][0] * det2_01_13 - c[2][1] * det2_01_03 + c[2][3] * det2_01_01;
444                 T det3_201_023 = c[2][0] * det2_01_23 - c[2][2] * det2_01_03 + c[2][3] * det2_01_02;
445                 T det3_201_123 = c[2][1] * det2_01_23 - c[2][2] * det2_01_13 + c[2][3] * det2_01_12;
446 
447                 T det = - det3_201_123 * c[3][0] + det3_201_023 * c[3][1] - det3_201_013 * c[3][2] + det3_201_012 * c[3][3];
448                 T invDet = 1 / det;
449 
450                 T det2_03_01 = c[0][0] * c[3][1] - c[0][1] * c[3][0];
451                 T det2_03_02 = c[0][0] * c[3][2] - c[0][2] * c[3][0];
452                 T det2_03_03 = c[0][0] * c[3][3] - c[0][3] * c[3][0];
453                 T det2_03_12 = c[0][1] * c[3][2] - c[0][2] * c[3][1];
454                 T det2_03_13 = c[0][1] * c[3][3] - c[0][3] * c[3][1];
455                 T det2_03_23 = c[0][2] * c[3][3] - c[0][3] * c[3][2];
456                 T det2_13_01 = c[1][0] * c[3][1] - c[1][1] * c[3][0];
457                 T det2_13_02 = c[1][0] * c[3][2] - c[1][2] * c[3][0];
458                 T det2_13_03 = c[1][0] * c[3][3] - c[1][3] * c[3][0];
459                 T det2_13_12 = c[1][1] * c[3][2] - c[1][2] * c[3][1];
460                 T det2_13_13 = c[1][1] * c[3][3] - c[1][3] * c[3][1];
461                 T det2_13_23 = c[1][2] * c[3][3] - c[1][3] * c[3][2];
462 
463                 T det3_203_012 = c[2][0] * det2_03_12 - c[2][1] * det2_03_02 + c[2][2] * det2_03_01;
464                 T det3_203_013 = c[2][0] * det2_03_13 - c[2][1] * det2_03_03 + c[2][3] * det2_03_01;
465                 T det3_203_023 = c[2][0] * det2_03_23 - c[2][2] * det2_03_03 + c[2][3] * det2_03_02;
466                 T det3_203_123 = c[2][1] * det2_03_23 - c[2][2] * det2_03_13 + c[2][3] * det2_03_12;
467 
468                 T det3_213_012 = c[2][0] * det2_13_12 - c[2][1] * det2_13_02 + c[2][2] * det2_13_01;
469                 T det3_213_013 = c[2][0] * det2_13_13 - c[2][1] * det2_13_03 + c[2][3] * det2_13_01;
470                 T det3_213_023 = c[2][0] * det2_13_23 - c[2][2] * det2_13_03 + c[2][3] * det2_13_02;
471                 T det3_213_123 = c[2][1] * det2_13_23 - c[2][2] * det2_13_13 + c[2][3] * det2_13_12;
472 
473                 T det3_301_012 = c[3][0] * det2_01_12 - c[3][1] * det2_01_02 + c[3][2] * det2_01_01;
474                 T det3_301_013 = c[3][0] * det2_01_13 - c[3][1] * det2_01_03 + c[3][3] * det2_01_01;
475                 T det3_301_023 = c[3][0] * det2_01_23 - c[3][2] * det2_01_03 + c[3][3] * det2_01_02;
476                 T det3_301_123 = c[3][1] * det2_01_23 - c[3][2] * det2_01_13 + c[3][3] * det2_01_12;
477 
478                 Matrix res = void;
479                 res.c[0][0] = - det3_213_123 * invDet;
480                 res.c[1][0] = + det3_213_023 * invDet;
481                 res.c[2][0] = - det3_213_013 * invDet;
482                 res.c[3][0] = + det3_213_012 * invDet;
483 
484                 res.c[0][1] = + det3_203_123 * invDet;
485                 res.c[1][1] = - det3_203_023 * invDet;
486                 res.c[2][1] = + det3_203_013 * invDet;
487                 res.c[3][1] = - det3_203_012 * invDet;
488 
489                 res.c[0][2] = + det3_301_123 * invDet;
490                 res.c[1][2] = - det3_301_023 * invDet;
491                 res.c[2][2] = + det3_301_013 * invDet;
492                 res.c[3][2] = - det3_301_012 * invDet;
493 
494                 res.c[0][3] = - det3_201_123 * invDet;
495                 res.c[1][3] = + det3_201_023 * invDet;
496                 res.c[2][3] = - det3_201_013 * invDet;
497                 res.c[3][3] = + det3_201_012 * invDet;
498                 return res;
499             }
500         }
501 
502         /// Returns a transposed copy of this matrix
503         /// Returns: transposed matrice.
504         @nogc Matrix!(T, C, R) transposed() pure const nothrow
505         {
506             Matrix!(T, C, R) res;
507             for (int i = 0; i < C; ++i)
508                 for (int j = 0; j < R; ++j)
509                     res.c[i][j] = c[j][i];
510             return res;
511         }
512 
513         static if (isSquare && R > 1)
514         {
515             /// Makes a diagonal matrix from a vector.
516             @nogc static Matrix diag(Vector!(T, R) v) pure nothrow
517             {
518                 Matrix res = void;
519                 for (int i = 0; i < R; ++i)
520                     for (int j = 0; j < C; ++j)
521                         res.c[i][j] = (i == j) ? v.v[i] : 0;
522                 return res;
523             }
524 
525             /// In-place translate by (v, 1)
526             @nogc void translate(Vector!(T, R-1) v) pure nothrow
527             {
528                 for (int i = 0; i < R; ++i)
529                 {
530                     T dot = 0;
531                     for (int j = 0; j + 1 < C; ++j)
532                         dot += v.v[j] * c[i][j];
533 
534                     c[i][C-1] += dot;
535                 }
536             }
537 
538             /// Make a translation matrix.
539             @nogc static Matrix translation(Vector!(T, R-1) v) pure nothrow
540             {
541                 Matrix res = identity();
542                 for (int i = 0; i + 1 < R; ++i)
543                     res.c[i][C-1] += v.v[i];
544                 return res;
545             }
546 
547             /// In-place matrix scaling.
548             void scale(Vector!(T, R-1) v) pure nothrow
549             {
550                 for (int i = 0; i < R; ++i)
551                     for (int j = 0; j + 1 < C; ++j)
552                         c[i][j] *= v.v[j];
553             }
554 
555             /// Make a scaling matrix.
556             @nogc static Matrix scaling(Vector!(T, R-1) v) pure nothrow
557             {
558                 Matrix res = identity();
559                 for (int i = 0; i + 1 < R; ++i)
560                     res.c[i][i] = v.v[i];
561                 return res;
562             }
563         }
564 
565         // rotations are implemented for 3x3 and 4x4 matrices.
566         static if (isSquare && (R == 3 || R == 4) && isFloatingPoint!T)
567         {
568             @nogc public static Matrix rotateAxis(int i, int j)(T angle) pure nothrow
569             {
570                 Matrix res = identity();
571                 const T cosa = cos(angle);
572                 const T sina = sin(angle);
573                 res.c[i][i] = cosa;
574                 res.c[i][j] = -sina;
575                 res.c[j][i] = sina;
576                 res.c[j][j] = cosa;
577                 return res;
578             }
579 
580             /// Rotate along X axis
581             /// Returns: rotation matrix along axis X
582             alias rotateAxis!(1, 2) rotateX;
583 
584             /// Rotate along Y axis
585             /// Returns: rotation matrix along axis Y
586             alias rotateAxis!(2, 0) rotateY;
587 
588             /// Rotate along Z axis
589             /// Returns: rotation matrix along axis Z
590             alias rotateAxis!(0, 1) rotateZ;
591 
592             /// Similar to the glRotate matrix, however the angle is expressed in radians
593             /// See_also: $(LINK http://www.cs.rutgers.edu/~decarlo/428/gl_man/rotate.html)
594             @nogc static Matrix rotation(T angle, vec3!T axis) pure nothrow
595             {
596                 Matrix res = identity();
597                 const T c = cos(angle);
598                 const oneMinusC = 1 - c;
599                 const T s = sin(angle);
600                 axis = axis.normalized();
601                 T x = axis.x,
602                   y = axis.y,
603                   z = axis.z;
604                 T xy = x * y,
605                   yz = y * z,
606                   xz = x * z;
607 
608                 res.c[0][0] = x * x * oneMinusC + c;
609                 res.c[0][1] = x * y * oneMinusC - z * s;
610                 res.c[0][2] = x * z * oneMinusC + y * s;
611                 res.c[1][0] = y * x * oneMinusC + z * s;
612                 res.c[1][1] = y * y * oneMinusC + c;
613                 res.c[1][2] = y * z * oneMinusC - x * s;
614                 res.c[2][0] = z * x * oneMinusC - y * s;
615                 res.c[2][1] = z * y * oneMinusC + x * s;
616                 res.c[2][2] = z * z * oneMinusC + c;
617                 return res;
618             }
619         }
620 
621         // 4x4 specific transformations for 3D usage
622         static if (isSquare && R == 4 && isFloatingPoint!T)
623         {
624             /// Orthographic projection
625             /// Returns: orthographic projection.
626             @nogc static Matrix orthographic(T left, T right, T bottom, T top, T near, T far) pure nothrow
627             {
628                 T dx = right - left,
629                   dy = top - bottom,
630                   dz = far - near;
631 
632                 T tx = -(right + left) / dx;
633                 T ty = -(top + bottom) / dy;
634                 T tz = -(far + near)   / dz;
635 
636                 return Matrix(2 / dx,   0,      0,    tx,
637                                 0,    2 / dy,   0,    ty,
638                                 0,      0,   -2 / dz, tz,
639                                 0,      0,      0,     1);
640             }
641 
642             /// Perspective projection
643             /// Returns: perspective projection.
644             @nogc static Matrix perspective(T FOVInRadians, T aspect, T zNear, T zFar) pure nothrow
645             {
646                 T f = 1 / tan(FOVInRadians / 2);
647                 T d = 1 / (zNear - zFar);
648 
649                 return Matrix(f / aspect, 0,                  0,                    0,
650                                        0, f,                  0,                    0,
651                                        0, 0, (zFar + zNear) * d, 2 * d * zFar * zNear,
652                                        0, 0,                 -1,                    0);
653             }
654 
655             /// Look At projection
656             /// Returns: "lookAt" projection.
657             /// Thanks to vuaru for corrections.
658             @nogc static Matrix lookAt(vec3!T eye, vec3!T target, vec3!T up) pure nothrow
659             {
660                 vec3!T Z = (eye - target).normalized();
661                 vec3!T X = cross(-up, Z).normalized();
662                 vec3!T Y = cross(Z, -X);
663 
664                 return Matrix(-X.x,        -X.y,        -X.z,      dot(X, eye),
665                                Y.x,         Y.y,         Y.z,     -dot(Y, eye),
666                                Z.x,         Z.y,         Z.z,     -dot(Z, eye),
667                                0,           0,           0,        1);
668             }
669 
670             /// Extract frustum from a 4x4 matrice.
671             @nogc Frustum!T frustum() pure const nothrow
672             {
673                 auto left   = Plane!T(row(3) + row(0));
674                 auto right  = Plane!T(row(3) - row(0));
675                 auto top    = Plane!T(row(3) - row(1));
676                 auto bottom = Plane!T(row(3) + row(1));
677                 auto near   = Plane!T(row(3) + row(2));
678                 auto far    = Plane!T(row(3) - row(2));
679                 return Frustum!T(left, right, top, bottom, near, far);
680             }
681 
682         }
683     }
684 
685     package
686     {
687         alias T _T;
688         enum _R = R;
689         enum _C = C;
690     }
691 
692     private
693     {
694         template isAssignable(T)
695         {
696             enum bool isAssignable = std.traits.isAssignable!(Matrix, T);
697         }
698 
699         template isConvertible(T)
700         {
701             enum bool isConvertible = (!is(T : Matrix)) && isAssignable!T;
702         }
703 
704         template isTAssignable(U)
705         {
706             enum bool isTAssignable = std.traits.isAssignable!(T, U);
707         }
708 
709         template isRowConvertible(U)
710         {
711             enum bool isRowConvertible = is(U : row_t);
712         }
713 
714         template isColumnConvertible(U)
715         {
716             enum bool isColumnConvertible = is(U : column_t);
717         }
718     }
719 
720     public
721     {
722         /// Construct an identity matrix
723         /// Returns: an identity matrix.
724         /// Note: the identity matrix, while only meaningful for square matrices,
725         /// is also defined for non-square ones.
726         @nogc static Matrix identity() pure nothrow
727         {
728             Matrix res = void;
729             for (int i = 0; i < R; ++i)
730                 for (int j = 0; j < C; ++j)
731                     res.c[i][j] = (i == j) ? 1 : 0;
732             return res;
733         }
734 
735         /// Construct an constant matrix
736         /// Returns: a constant matrice.
737         @nogc static Matrix constant(U)(U x) pure nothrow
738         {
739             Matrix res = void;
740 
741             for (int i = 0; i < R * C; ++i)
742                 res.v[i] = cast(T)x;
743             return res;
744         }
745     }
746 }
747 
748 template isMatrixInstantiation(U)
749 {
750     private static void isMatrix(T, int R, int C)(Matrix!(T, R, C) x)
751     {
752     }
753 
754     enum bool isMatrixInstantiation = is(typeof(isMatrix(U.init)));
755 }
756 
757 // GLSL is a big inspiration here
758 // we defines types with more or less the same names
759 
760 ///
761 template mat2x2(T) { alias Matrix!(T, 2, 2) mat2x2; }
762 ///
763 template mat3x3(T) { alias Matrix!(T, 3, 3) mat3x3; }
764 ///
765 template mat4x4(T) { alias Matrix!(T, 4, 4) mat4x4; }
766 
767 // WARNING: in GLSL, first number is _columns_, second is rows
768 // It is the opposite here: first number is rows, second is columns
769 // With this convention mat2x3 * mat3x4 -> mat2x4.
770 
771 ///
772 template mat2x3(T) { alias Matrix!(T, 2, 3) mat2x3; }
773 ///
774 template mat2x4(T) { alias Matrix!(T, 2, 4) mat2x4; }
775 ///
776 template mat3x2(T) { alias Matrix!(T, 3, 2) mat3x2; }
777 ///
778 template mat3x4(T) { alias Matrix!(T, 3, 4) mat3x4; }
779 ///
780 template mat4x2(T) { alias Matrix!(T, 4, 2) mat4x2; }
781 ///
782 template mat4x3(T) { alias Matrix!(T, 4, 3) mat4x3; }
783 
784 // shorter names for most common matrices
785 alias mat2x2 mat2;///
786 alias mat3x3 mat3;///
787 alias mat4x4 mat4;///
788 
789 // Define a lot of type names
790 // Most useful are probably mat4f and mat4d
791 
792 alias mat2!float  mat2f;///
793 alias mat2!double mat2d;///
794 
795 alias mat3!float  mat3f;///
796 alias mat3!double mat3d;///
797 
798 alias mat4!float  mat4f;///
799 alias mat4!double mat4d;///
800 
801 alias mat2x2!float  mat2x2f;///
802 alias mat2x2!double mat2x2d;///
803 
804 alias mat3x3!float  mat3x3f;///
805 alias mat3x3!double mat3x3d;///
806 
807 alias mat4x4!float  mat4x4f;///
808 alias mat4x4!double mat4x4d;///
809 
810 unittest
811 {
812     alias mat2i = mat2!int;
813     alias mat2x3f = mat2x3!float;
814     alias mat3x4f = mat3x4!float;
815     alias mat2x4f = mat2x4!float;
816 
817     mat2i x = mat2i(0, 1,
818                     2, 3);
819     assert(x.c[0][0] == 0 && x.c[0][1] == 1 && x.c[1][0] == 2 && x.c[1][1] == 3);
820 
821     vec2i[2] cols = [vec2i(0, 2), vec2i(1, 3)];
822     mat2i y = mat2i.fromColumns(cols[]);
823     assert(y.c[0][0] == 0 && y.c[0][1] == 1 && y.c[1][0] == 2 && y.c[1][1] == 3);
824     y = mat2i.fromRows(cols[]);
825     assert(y.c[0][0] == 0 && y.c[1][0] == 1 && y.c[0][1] == 2 && y.c[1][1] == 3);
826     y = y.transposed();
827 
828     assert(x == y);
829     x = [0, 1, 2, 3];
830     assert(x == y);
831 
832     mat2i z = x * y;
833     assert(z == mat2i([2, 3, 6, 11]));
834     vec2i vz = z * vec2i(2, -1);
835     assert(vz == vec2i(1, 1));
836 
837     mat2f a = z;
838     mat2d ad = a;
839     ad += a;
840     mat2f w = [4, 5, 6, 7];
841     z = cast(mat2i)w;
842     assert(w == z);
843 
844     {
845         mat2x3f A;
846         mat3x4f B;
847         mat2x4f C = A * B;
848     }
849 
850     assert(mat2i.diag(vec2i(1, 2)) == mat2i(1, 0,
851                                             0, 2));
852 
853     // Construct with a single scalar
854     auto D = mat4f(1.0f);
855 }
856 
857 // Issue #206 (matrix *= scalar) not yielding matrix * scalar but matrix * matrix(scalar)
858 unittest
859 {
860     mat4f mvp = mat4f.identity;
861     mvp *= 2;
862     assert(mvp == mat4f(2, 0, 0, 0,
863                         0, 2, 0, 0,
864                         0, 0, 2, 0,
865                         0, 0, 0, 2));
866 
867     mvp = mat4f.identity * 2;
868     assert(mvp == mat4f(2, 0, 0, 0,
869                         0, 2, 0, 0,
870                         0, 0, 2, 0,
871                         0, 0, 0, 2));
872 
873 
874     mvp = mat4f(1) * mat4f(1);
875     assert(mvp == mat4f(4, 4, 4, 4,
876                         4, 4, 4, 4,
877                         4, 4, 4, 4,
878                         4, 4, 4, 4));
879 
880     mvp = mat4f(1);
881     mvp *= mat4f(1);
882     assert(mvp == mat4f(4, 4, 4, 4,
883                         4, 4, 4, 4,
884                         4, 4, 4, 4,
885                         4, 4, 4, 4));
886 }