288 lines
8.6 KiB
C
288 lines
8.6 KiB
C
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/*
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Copyright 2010 Google Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#ifndef GrPoint_DEFINED
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#define GrPoint_DEFINED
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#include "GrTypes.h"
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#include "GrScalar.h"
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/**
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* 2D Point struct
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*/
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struct GrPoint {
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public:
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GrScalar fX, fY;
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GrPoint() {}
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GrPoint(GrScalar x, GrScalar y) { fX = x; fY = y; }
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GrScalar x() const { return fX; }
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GrScalar y() const { return fY; }
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void set(GrScalar x, GrScalar y) {
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fX = x;
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fY = y;
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}
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void setAsMidPoint(const GrPoint& a, const GrPoint& b) {
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fX = GrScalarAve(a.fX, b.fX);
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fY = GrScalarAve(a.fY, b.fY);
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}
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void offset(GrScalar dx, GrScalar dy) {
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fX += dx;
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fY += dy;
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}
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GrScalar distanceToSqd(const GrPoint& p) const {
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GrScalar dx = (p.fX - fX);
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GrScalar dy = (p.fY - fY);
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return GrMul(dx, dx) + GrMul(dy, dy);
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}
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GrScalar distanceTo(const GrPoint& p) const {
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// TODO: fixed point sqrt
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return GrFloatToScalar(sqrtf(GrScalarToFloat(distanceToSqd(p))));
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}
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GrScalar distanceToOriginSqd() const {
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return GrMul(fX, fX) + GrMul(fY, fY);
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}
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GrScalar distanceToOrigin() const {
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return GrFloatToScalar(sqrtf(GrScalarToFloat(distanceToOriginSqd())));
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}
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inline GrScalar distanceToLineBetweenSqd(const GrPoint& a,
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const GrPoint& b) const;
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inline GrScalar distanceToLineBetween(const GrPoint& a,
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const GrPoint& b) const;
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inline GrScalar distanceToLineSegmentBetweenSqd(const GrPoint& a,
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const GrPoint& b) const;
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inline GrScalar distanceToLineSegmentBetween(const GrPoint& a,
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const GrPoint& b) const;
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// counter-clockwise fan
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void setRectFan(GrScalar l, GrScalar t, GrScalar r, GrScalar b) {
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GrPoint* v = this;
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v[0].set(l, t);
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v[1].set(l, b);
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v[2].set(r, b);
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v[3].set(r, t);
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}
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void setRectFan(GrScalar l, GrScalar t, GrScalar r, GrScalar b, size_t stride) {
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GrAssert(stride >= sizeof(GrPoint));
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((GrPoint*)((intptr_t)this + 0 * stride))->set(l, t);
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((GrPoint*)((intptr_t)this + 1 * stride))->set(l, b);
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((GrPoint*)((intptr_t)this + 2 * stride))->set(r, b);
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((GrPoint*)((intptr_t)this + 3 * stride))->set(r, t);
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}
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// counter-clockwise fan
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void setIRectFan(int l, int t, int r, int b) {
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GrPoint* v = this;
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v[0].set(GrIntToScalar(l), GrIntToScalar(t));
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v[1].set(GrIntToScalar(l), GrIntToScalar(b));
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v[2].set(GrIntToScalar(r), GrIntToScalar(b));
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v[3].set(GrIntToScalar(r), GrIntToScalar(t));
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}
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void setIRectFan(int l, int t, int r, int b, size_t stride) {
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GrAssert(stride >= sizeof(GrPoint));
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((GrPoint*)((intptr_t)this + 0 * stride))->set(GrIntToScalar(l),
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GrIntToScalar(t));
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((GrPoint*)((intptr_t)this + 1 * stride))->set(GrIntToScalar(l),
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GrIntToScalar(b));
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((GrPoint*)((intptr_t)this + 2 * stride))->set(GrIntToScalar(r),
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GrIntToScalar(b));
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((GrPoint*)((intptr_t)this + 3 * stride))->set(GrIntToScalar(r),
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GrIntToScalar(t));
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}
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bool operator ==(const GrPoint& p) const {
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return fX == p.fX && fY == p.fY;
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}
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bool operator !=(const GrPoint& p) const {
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return fX != p.fX || fY != p.fY;
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}
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};
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struct GrIPoint16 {
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int16_t fX, fY;
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void set(intptr_t x, intptr_t y) {
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fX = GrToS16(x);
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fY = GrToS16(y);
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}
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};
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struct GrVec {
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public:
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GrScalar fX, fY;
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GrVec() {}
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GrVec(GrScalar x, GrScalar y) { fX = x; fY = y; }
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GrScalar x() const { return fX; }
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GrScalar y() const { return fY; }
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/**
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* set x and y length of the vector.
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*/
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void set(GrScalar x, GrScalar y) {
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fX = x;
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fY = y;
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}
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/**
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* set vector to point from a to b.
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*/
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void setBetween(const GrPoint& a, const GrPoint& b) {
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fX = b.fX - a.fX;
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fY = b.fY - a.fY;
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}
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/**
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* length of the vector squared.
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*/
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GrScalar lengthSqd() const {
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return GrMul(fX, fX) + GrMul(fY, fY);
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}
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/**
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* length of the vector.
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*/
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GrScalar length() const {
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// TODO: fixed point sqrt
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return GrFloatToScalar(sqrtf(GrScalarToFloat(lengthSqd())));
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}
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/**
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* normalizes the vector if it's length is not 0.
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* @return true if normalized, otherwise false.
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*/
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bool normalize() {
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GrScalar l = lengthSqd();
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if (l) {
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// TODO: fixed point sqrt and invert
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l = 1 / sqrtf(l);
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fX *= l;
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fY *= l;
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return true;
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}
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return false;
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}
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/**
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* Dot product of this with vec.
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*/
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GrScalar dot(const GrVec& vec) const {
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return GrMul(vec.fX, fX) + GrMul(vec.fY, fY);
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}
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/**
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* z-value of this cross vec.
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*/
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GrScalar cross(const GrVec& vec) const {
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return GrMul(fX, vec.fY) - GrMul(fY, vec.fX);
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}
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bool operator ==(const GrPoint& p) const {
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return fX == p.fX && fY == p.fY;
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}
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bool operator !=(const GrPoint& p) const {
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return fX != p.fX || fY != p.fY;
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}
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};
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GrScalar GrPoint::distanceToLineBetweenSqd(const GrPoint& a,
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const GrPoint& b) const {
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// Let d be the distance between c (this) and line ab.
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// The area of the triangle defined by a, b, and c is
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// A = |b-a|*d/2. Let u = b-a and v = c-a. The cross product of
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// u and v is aligned with the z axis and its magnitude is 2A.
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// So d = |u x v| / |u|.
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GrVec u, v;
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u.setBetween(a,b);
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v.setBetween(a,*this);
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GrScalar det = u.cross(v);
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return (GrMul(det, det)) / u.lengthSqd();
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}
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GrScalar GrPoint::distanceToLineBetween(const GrPoint& a,
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const GrPoint& b) const {
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GrVec u, v;
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u.setBetween(a,b);
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v.setBetween(a,*this);
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GrScalar det = u.cross(v);
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return (GrScalarAbs(det)) / u.length();
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}
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GrScalar GrPoint::distanceToLineSegmentBetweenSqd(const GrPoint& a,
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const GrPoint& b) const {
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// See comments to distanceToLineBetweenSqd. If the projection of c onto
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// u is between a and b then this returns the same result as that
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// function. Otherwise, it returns the distance to the closer of a and
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// b. Let the projection of v onto u be v'. There are three cases:
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// 1. v' points opposite to u. c is not between a and b and is closer
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// to a than b.
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// 2. v' points along u and has magnitude less than y. c is between
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// a and b and the distance to the segment is the same as distance
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// to the line ab.
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// 3. v' points along u and has greater magnitude than u. c is not
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// not between a and b and is closer to b than a.
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// v' = (u dot v) * u / |u|. So if (u dot v)/|u| is less than zero we're
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// in case 1. If (u dot v)/|u| is > |u| we are in case 3. Otherwise
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// we're in case 2. We actually compare (u dot v) to 0 and |u|^2 to
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// avoid a sqrt to compute |u|.
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GrVec u, v;
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u.setBetween(a,b);
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v.setBetween(a,*this);
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GrScalar uLengthSqd = u.lengthSqd();
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GrScalar uDotV = u.dot(v);
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if (uDotV <= 0) {
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return v.lengthSqd();
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} else if (uDotV > uLengthSqd) {
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return b.distanceToSqd(*this);
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} else {
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GrScalar det = u.cross(v);
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return (GrMul(det, det)) / uLengthSqd;
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}
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}
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GrScalar GrPoint::distanceToLineSegmentBetween(const GrPoint& a,
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const GrPoint& b) const {
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// TODO: fixed point sqrt
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return GrFloatToScalar(sqrtf(GrScalarToFloat(distanceToLineSegmentBetweenSqd(a,b))));
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}
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#endif
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