140 lines
2.3 KiB
Go
140 lines
2.3 KiB
Go
package canvas
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import (
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"fmt"
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"math"
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)
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type vec [2]float64
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func (v vec) String() string {
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return fmt.Sprintf("[%f,%f]", v[0], v[1])
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}
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func (v vec) add(v2 vec) vec {
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return vec{v[0] + v2[0], v[1] + v2[1]}
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}
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func (v vec) sub(v2 vec) vec {
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return vec{v[0] - v2[0], v[1] - v2[1]}
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}
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func (v vec) mul(v2 vec) vec {
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return vec{v[0] * v2[0], v[1] * v2[1]}
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}
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func (v vec) mulf(f float64) vec {
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return vec{v[0] * f, v[1] * f}
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}
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func (v vec) mulMat(m mat) vec {
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return vec{
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m[0]*v[0] + m[2]*v[1] + m[4],
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m[1]*v[0] + m[3]*v[1] + m[5]}
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}
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func (v vec) mulMat2(m mat2) vec {
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return vec{m[0]*v[0] + m[2]*v[1], m[1]*v[0] + m[3]*v[1]}
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}
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func (v vec) div(v2 vec) vec {
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return vec{v[0] / v2[0], v[1] / v2[1]}
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}
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func (v vec) divf(f float64) vec {
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return vec{v[0] / f, v[1] / f}
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}
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func (v vec) dot(v2 vec) float64 {
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return v[0]*v2[0] + v[1]*v2[1]
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}
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func (v vec) len() float64 {
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return math.Sqrt(v[0]*v[0] + v[1]*v[1])
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}
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func (v vec) lenSqr() float64 {
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return v[0]*v[0] + v[1]*v[1]
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}
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func (v vec) norm() vec {
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return v.mulf(1.0 / v.len())
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}
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func (v vec) atan2() float64 {
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return math.Atan2(v[1], v[0])
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}
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func (v vec) angle() float64 {
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return math.Pi*0.5 - math.Atan2(v[1], v[0])
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}
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func (v vec) angleTo(v2 vec) float64 {
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return math.Acos(v.norm().dot(v2.norm()))
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}
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type mat [6]float64
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func (m *mat) String() string {
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return fmt.Sprintf("[%f,%f,0,\n %f,%f,0,\n %f,%f,1,]", m[0], m[2], m[4], m[1], m[3], m[5])
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}
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var matIdentity = mat{
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1, 0,
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0, 1,
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0, 0}
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func matTranslate(v vec) mat {
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return mat{
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1, 0,
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0, 1,
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v[0], v[1]}
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}
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func matScale(v vec) mat {
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return mat{
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v[0], 0,
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0, v[1],
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0, 0}
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}
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func matRotate(radians float64) mat {
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s, c := math.Sincos(radians)
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return mat{
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c, s,
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-s, c,
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0, 0}
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}
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func (m mat) mul(m2 mat) mat {
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return mat{
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m[0]*m2[0] + m[1]*m2[2],
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m[0]*m2[1] + m[1]*m2[3],
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m[2]*m2[0] + m[3]*m2[2],
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m[2]*m2[1] + m[3]*m2[3],
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m[4]*m2[0] + m[5]*m2[2] + m2[4],
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m[4]*m2[1] + m[5]*m2[3] + m2[5]}
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}
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func (m mat) invert() mat {
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identity := 1.0 / (m[0]*m[3] - m[2]*m[1])
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return mat{
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m[3] * identity,
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-m[1] * identity,
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-m[2] * identity,
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m[0] * identity,
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(m[2]*m[5] - m[3]*m[4]) * identity,
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(m[1]*m[4] - m[0]*m[5]) * identity,
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}
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}
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type mat2 [4]float64
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func (m mat) mat2() mat2 {
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return mat2{m[0], m[1], m[2], m[3]}
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}
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func (m *mat2) String() string {
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return fmt.Sprintf("[%f,%f,\n %f,%f]", m[0], m[2], m[1], m[3])
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}
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