Wayland compositor (wlroots)
git clone https://git.lucas.co/cce-compositor.git
scenefx/util/matrix.c (3.9K)
1 #include <assert.h>
2 #include <string.h>
3 #include <wayland-server-protocol.h>
4 #include <wlr/util/box.h>
5 #include "util/matrix.h"
6
7 void wlr_matrix_identity(float mat[static 9]) {
8 static const float identity[9] = {
9 1.0f, 0.0f, 0.0f,
10 0.0f, 1.0f, 0.0f,
11 0.0f, 0.0f, 1.0f,
12 };
13 memcpy(mat, identity, sizeof(identity));
14 }
15
16 void wlr_matrix_multiply(float mat[static 9], const float a[static 9],
17 const float b[static 9]) {
18 float product[9];
19
20 product[0] = a[0]*b[0] + a[1]*b[3] + a[2]*b[6];
21 product[1] = a[0]*b[1] + a[1]*b[4] + a[2]*b[7];
22 product[2] = a[0]*b[2] + a[1]*b[5] + a[2]*b[8];
23
24 product[3] = a[3]*b[0] + a[4]*b[3] + a[5]*b[6];
25 product[4] = a[3]*b[1] + a[4]*b[4] + a[5]*b[7];
26 product[5] = a[3]*b[2] + a[4]*b[5] + a[5]*b[8];
27
28 product[6] = a[6]*b[0] + a[7]*b[3] + a[8]*b[6];
29 product[7] = a[6]*b[1] + a[7]*b[4] + a[8]*b[7];
30 product[8] = a[6]*b[2] + a[7]*b[5] + a[8]*b[8];
31
32 memcpy(mat, product, sizeof(product));
33 }
34
35 void wlr_matrix_translate(float mat[static 9], float x, float y) {
36 float translate[9] = {
37 1.0f, 0.0f, x,
38 0.0f, 1.0f, y,
39 0.0f, 0.0f, 1.0f,
40 };
41 wlr_matrix_multiply(mat, mat, translate);
42 }
43
44 void wlr_matrix_scale(float mat[static 9], float x, float y) {
45 float scale[9] = {
46 x, 0.0f, 0.0f,
47 0.0f, y, 0.0f,
48 0.0f, 0.0f, 1.0f,
49 };
50 wlr_matrix_multiply(mat, mat, scale);
51 }
52
53 static const float transforms[][9] = {
54 [WL_OUTPUT_TRANSFORM_NORMAL] = {
55 1.0f, 0.0f, 0.0f,
56 0.0f, 1.0f, 0.0f,
57 0.0f, 0.0f, 1.0f,
58 },
59 [WL_OUTPUT_TRANSFORM_90] = {
60 0.0f, 1.0f, 0.0f,
61 -1.0f, 0.0f, 0.0f,
62 0.0f, 0.0f, 1.0f,
63 },
64 [WL_OUTPUT_TRANSFORM_180] = {
65 -1.0f, 0.0f, 0.0f,
66 0.0f, -1.0f, 0.0f,
67 0.0f, 0.0f, 1.0f,
68 },
69 [WL_OUTPUT_TRANSFORM_270] = {
70 0.0f, -1.0f, 0.0f,
71 1.0f, 0.0f, 0.0f,
72 0.0f, 0.0f, 1.0f,
73 },
74 [WL_OUTPUT_TRANSFORM_FLIPPED] = {
75 -1.0f, 0.0f, 0.0f,
76 0.0f, 1.0f, 0.0f,
77 0.0f, 0.0f, 1.0f,
78 },
79 [WL_OUTPUT_TRANSFORM_FLIPPED_90] = {
80 0.0f, 1.0f, 0.0f,
81 1.0f, 0.0f, 0.0f,
82 0.0f, 0.0f, 1.0f,
83 },
84 [WL_OUTPUT_TRANSFORM_FLIPPED_180] = {
85 1.0f, 0.0f, 0.0f,
86 0.0f, -1.0f, 0.0f,
87 0.0f, 0.0f, 1.0f,
88 },
89 [WL_OUTPUT_TRANSFORM_FLIPPED_270] = {
90 0.0f, -1.0f, 0.0f,
91 -1.0f, 0.0f, 0.0f,
92 0.0f, 0.0f, 1.0f,
93 },
94 };
95
96 void wlr_matrix_transform(float mat[static 9],
97 enum wl_output_transform transform) {
98 wlr_matrix_multiply(mat, mat, transforms[transform]);
99 }
100
101 void matrix_projection(float mat[static 9], int width, int height,
102 enum wl_output_transform transform) {
103 memset(mat, 0, sizeof(*mat) * 9);
104
105 const float *t = transforms[transform];
106 float x = 2.0f / width;
107 float y = 2.0f / height;
108
109 // Rotation + reflection
110 mat[0] = x * t[0];
111 mat[1] = x * t[1];
112 mat[3] = y * -t[3];
113 mat[4] = y * -t[4];
114
115 // Translation
116 mat[2] = -copysign(1.0f, mat[0] + mat[1]);
117 mat[5] = -copysign(1.0f, mat[3] + mat[4]);
118
119 // Identity
120 mat[8] = 1.0f;
121 }
122
123 void wlr_matrix_project_box(float mat[static 9], const struct wlr_box *box,
124 enum wl_output_transform transform, const float projection[static 9]) {
125 int x = box->x;
126 int y = box->y;
127 int width = box->width;
128 int height = box->height;
129
130 wlr_matrix_identity(mat);
131 wlr_matrix_translate(mat, x, y);
132
133 wlr_matrix_scale(mat, width, height);
134
135 if (transform != WL_OUTPUT_TRANSFORM_NORMAL) {
136 wlr_matrix_translate(mat, 0.5, 0.5);
137 wlr_matrix_transform(mat, transform);
138 wlr_matrix_translate(mat, -0.5, -0.5);
139 }
140
141 wlr_matrix_multiply(mat, projection, mat);
142 }
143
144 void matrix_invert(float out[static 9], float m[static 9]) {
145 float a = m[0], b = m[1], c = m[2], d = m[3], e = m[4], f = m[5], g = m[6], h = m[7], i = m[8];
146
147 // See: https://en.wikipedia.org/wiki/Determinant
148 float det = a*e*i + b*f*g + c*d*h - c*e*g - b*d*i - a*f*h;
149 assert(det != 0);
150 float inv_det = 1 / det;
151
152 // See: https://en.wikipedia.org/wiki/Invertible_matrix#Inversion_of_3_%C3%97_3_matrices
153 float result[] = {
154 inv_det * (e*i - f*h),
155 inv_det * -(b*i - c*h),
156 inv_det * (b*f - c*e),
157 inv_det * -(d*i - f*g),
158 inv_det * (a*i - c*g),
159 inv_det * -(a*f - c*d),
160 inv_det * (d*h - e*g),
161 inv_det * -(a*h - b*g),
162 inv_det * (a*e - b*d),
163 };
164 memcpy(out, result, sizeof(result));
165 }