7 return (Transform) { .a1 = 1.0f, .a2 = 0.0f, .a3 = 0.0f, .a4 = 0.0f,
8 .b1 = 0.0f, .b2 = 1.0f, .b3 = 0.0f, .b4 = 0.0f,
9 .c1 = 0.0f, .c2 = 0.0f, .c3 = 1.0f, .c4 = 0.0f,
10 .d1 = 0.0f, .d2 = 0.0f, .d3 = 0.0f, .d4 = 1.0f };
13 Transform multiply(Transform t1, Transform t2) {
14 GLfloat* a = (GLfloat*) &t1;
15 GLfloat* b = (GLfloat*) &t2;
17 GLfloat* c = (GLfloat*) &result;
19 for (size_t row = 0; row < 4; ++row) {
20 for (size_t col = 0; col < 4; ++col) {
22 a[(row * 4) + 0] * b[(0 * 4) + col]
23 + a[(row * 4) + 1] * b[(1 * 4) + col]
24 + a[(row * 4) + 2] * b[(2 * 4) + col]
25 + a[(row * 4) + 3] * b[(3 * 4) + col];
31 void translate(Transform* transform, Vector vec) {
32 *transform = multiply(
33 (Transform) { .a1 = 1.0f, .a2 = 0.0f, .a3 = 0.0f, .a4 = vec.x,
34 .b1 = 0.0f, .b2 = 1.0f, .b3 = 0.0f, .b4 = vec.y,
35 .c1 = 0.0f, .c2 = 0.0f, .c3 = 1.0f, .c4 = vec.z,
36 .d1 = 0.0f, .d2 = 0.0f, .d3 = 0.0f, .d4 = 1.0f },
40 void rotate(Transform* transform, Vector axis, float angle) {
41 axis = normalized(axis);
45 float sinA = sinf(angle);
46 float cosA = cosf(angle);
47 float omcA = 1 - cosA;
49 *transform = multiply(
50 (Transform) { l*l*omcA + cosA, m*l*omcA - n*sinA, n*l*omcA + m*sinA, 0.0f,
51 l*m*omcA + n*sinA, m*m*omcA + cosA, n*m*omcA - l*sinA, 0.0f,
52 l*n*omcA - m*sinA, m*n*omcA + l*sinA, n*n*omcA + cosA, 0.0f,
53 0.0f, 0.0f, 0.0f, 1.0f },
57 Vector addVectors(Vector v1, Vector v2){
58 return (Vector) { v1.x + v2.x, v1.y + v2.y, v1.z + v2.z };
61 Vector subtractVectors(Vector v1, Vector v2) {
62 return (Vector) { v1.x - v2.x, v1.y - v2.y, v1.z - v2.z };
65 Vector crossProduct(Vector v1, Vector v2) {
66 return (Vector) { .x = (v1.y * v2.z) - (v1.z * v2.y),
67 .y = (v1.z * v2.x) - (v1.x * v2.z),
68 .z = (v1.x * v2.y) - (v1.y * v2.x) };
71 float dotProduct(Vector v1, Vector v2) {
72 return (v1.x * v2.x) + (v1.y * v2.y) + (v1.z * v2.z);
75 Vector scaleVector(Vector vec, float scale) {
76 return (Vector) { vec.x * scale,
81 Vector growVectorNoFlip(Vector vec, float amount) {
82 float mag = magnitude(vec);
83 float factor = (mag + amount) / mag;
87 return scaleVector(vec, factor);
90 Vector clampMagnitude(Vector vec, float maxMagnitude) {
91 float m = magnitude(vec);
92 if (m > maxMagnitude) {
93 vec = scaleVector(vec, maxMagnitude / m);
98 float magnitude(Vector vec) {
99 return sqrtf(vec.x * vec.x + vec.y * vec.y + vec.z * vec.z);
102 Vector applyTransform(Transform transform, Vector vec) {
103 GLfloat* a = (GLfloat*) &transform;
104 GLfloat b[4] = { vec.x, vec.y, vec.z, 1.0f };
107 for (size_t row = 0; row < 4; ++row) {
109 a[(row * 4) + 0] * b[0]
110 + a[(row * 4) + 1] * b[1]
111 + a[(row * 4) + 2] * b[2]
112 + a[(row * 4) + 3] * b[3];
114 return (Vector) { c[0], c[1], c[2] };
117 Vector translationOf(Transform transform) {
118 return (Vector) { transform.a4, transform.b4, transform.c4 };
121 Vector normalized(Vector vec) {
122 float m = magnitude(vec);
123 return (Vector) { vec.x / m, vec.y / m, vec.z / m };