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- /*
- * Copyright 2018 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #include "include/utils/Sk3D.h"
- static void set_col(SkMatrix44* m, int col, const SkPoint3& v) {
- m->set(0, col, v.fX);
- m->set(1, col, v.fY);
- m->set(2, col, v.fZ);
- }
- static SkPoint3 cross(const SkPoint3& a, const SkPoint3& b) {
- return {
- a.fY * b.fZ - a.fZ * b.fY,
- a.fZ * b.fX - a.fX * b.fZ,
- a.fX * b.fY - a.fY * b.fX,
- };
- }
- void Sk3LookAt(SkMatrix44* dst, const SkPoint3& eye, const SkPoint3& center, const SkPoint3& up) {
- SkPoint3 f = center - eye;
- f.normalize();
- SkPoint3 u = up;
- u.normalize();
- SkPoint3 s = cross(f, u);
- s.normalize();
- u = cross(s, f);
- dst->setIdentity();
- set_col(dst, 0, s);
- set_col(dst, 1, u);
- set_col(dst, 2, -f);
- set_col(dst, 3, eye);
- dst->invert(dst);
- }
- bool Sk3Perspective(SkMatrix44* dst, float near, float far, float angle) {
- SkASSERT(far > near);
- float denomInv = sk_ieee_float_divide(1, far - near);
- float halfAngle = angle * 0.5f;
- float cot = sk_float_cos(halfAngle) / sk_float_sin(halfAngle);
- dst->setIdentity();
- dst->set(0, 0, cot);
- dst->set(1, 1, cot);
- dst->set(2, 2, (far + near) * denomInv);
- dst->set(2, 3, 2 * far * near * denomInv);
- dst->set(3, 2, -1);
- return true;
- }
- void Sk3MapPts(SkPoint dst[], const SkMatrix44& m4, const SkPoint3 src[], int count) {
- for (int i = 0; i < count; ++i) {
- SkVector4 v = m4 * SkVector4{ src[i].fX, src[i].fY, src[i].fZ, 1 };
- // clip v;
- dst[i] = { v.fData[0] / v.fData[3], v.fData[1] / v.fData[3] };
- }
- }
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