1 /*
2 * Copyright 2018 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "include/utils/Sk3D.h"
9
set_col(SkMatrix44 * m,int col,const SkPoint3 & v)10 static void set_col(SkMatrix44* m, int col, const SkPoint3& v) {
11 m->set(0, col, v.fX);
12 m->set(1, col, v.fY);
13 m->set(2, col, v.fZ);
14 }
15
cross(const SkPoint3 & a,const SkPoint3 & b)16 static SkPoint3 cross(const SkPoint3& a, const SkPoint3& b) {
17 return {
18 a.fY * b.fZ - a.fZ * b.fY,
19 a.fZ * b.fX - a.fX * b.fZ,
20 a.fX * b.fY - a.fY * b.fX,
21 };
22 }
23
Sk3LookAt(SkMatrix44 * dst,const SkPoint3 & eye,const SkPoint3 & center,const SkPoint3 & up)24 void Sk3LookAt(SkMatrix44* dst, const SkPoint3& eye, const SkPoint3& center, const SkPoint3& up) {
25 SkPoint3 f = center - eye;
26 f.normalize();
27 SkPoint3 u = up;
28 u.normalize();
29 SkPoint3 s = cross(f, u);
30 s.normalize();
31 u = cross(s, f);
32
33 dst->setIdentity();
34 set_col(dst, 0, s);
35 set_col(dst, 1, u);
36 set_col(dst, 2, -f);
37 set_col(dst, 3, eye);
38 dst->invert(dst);
39 }
40
Sk3Perspective(SkMatrix44 * dst,float near,float far,float angle)41 bool Sk3Perspective(SkMatrix44* dst, float near, float far, float angle) {
42 SkASSERT(far > near);
43
44 float denomInv = sk_ieee_float_divide(1, far - near);
45 float halfAngle = angle * 0.5f;
46 float cot = sk_float_cos(halfAngle) / sk_float_sin(halfAngle);
47
48 dst->setIdentity();
49 dst->set(0, 0, cot);
50 dst->set(1, 1, cot);
51 dst->set(2, 2, (far + near) * denomInv);
52 dst->set(2, 3, 2 * far * near * denomInv);
53 dst->set(3, 2, -1);
54 return true;
55 }
56
Sk3MapPts(SkPoint dst[],const SkMatrix44 & m4,const SkPoint3 src[],int count)57 void Sk3MapPts(SkPoint dst[], const SkMatrix44& m4, const SkPoint3 src[], int count) {
58 for (int i = 0; i < count; ++i) {
59 SkVector4 v = m4 * SkVector4{ src[i].fX, src[i].fY, src[i].fZ, 1 };
60 // clip v;
61 dst[i] = { v.fData[0] / v.fData[3], v.fData[1] / v.fData[3] };
62 }
63 }
64
65