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Optimize multiplication operators to avoid allocations
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@romainguy
romainguy committed Jul 21, 2021
1 parent 28dddee commit db86d8e
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Showing 2 changed files with 115 additions and 36 deletions.
105 changes: 69 additions & 36 deletions src/main/kotlin/com/curiouscreature/kotlin/math/Matrix.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -82,18 +82,22 @@ data class Mat2(
operator fun times(v: Float) = Mat2(x * v, y * v)
operator fun div(v: Float) = Mat2(x / v, y / v)

operator fun times(m: Mat2): Mat2 {
val t = transpose(this)
return Mat2(
Float2(dot(t.x, m.x), dot(t.y, m.x)),
Float2(dot(t.x, m.y), dot(t.y, m.y))
)
}
operator fun times(m: Mat2) = Mat2(
Float2(
x.x * m.x.x + y.x * m.x.y,
x.y * m.x.x + y.y * m.x.y,
),
Float2(
x.x * m.y.x + y.x * m.y.y,
x.y * m.y.x + y.y * m.y.y,
)
)

operator fun times(v: Float2) = Float2(
x.x * v.x + y.x * v.y,
x.y * v.x + y.y * v.y,
)

operator fun times(v: Float2): Float2 {
val t = transpose(this)
return Float2(dot(t.x, v), dot(t.y, v))
}

fun toFloatArray() = floatArrayOf(
x.x, y.x,
Expand Down Expand Up @@ -173,19 +177,29 @@ data class Mat3(
operator fun times(v: Float) = Mat3(x * v, y * v, z * v)
operator fun div(v: Float) = Mat3(x / v, y / v, z / v)

operator fun times(m: Mat3): Mat3 {
val t = transpose(this)
return Mat3(
Float3(dot(t.x, m.x), dot(t.y, m.x), dot(t.z, m.x)),
Float3(dot(t.x, m.y), dot(t.y, m.y), dot(t.z, m.y)),
Float3(dot(t.x, m.z), dot(t.y, m.z), dot(t.z, m.z))
)
}
operator fun times(m: Mat3) = Mat3(
Float3(
x.x * m.x.x + y.x * m.x.y + z.x * m.x.z,
x.y * m.x.x + y.y * m.x.y + z.y * m.x.z,
x.z * m.x.x + y.z * m.x.y + z.z * m.x.z,
),
Float3(
x.x * m.y.x + y.x * m.y.y + z.x * m.y.z,
x.y * m.y.x + y.y * m.y.y + z.y * m.y.z,
x.z * m.y.x + y.z * m.y.y + z.z * m.y.z,
),
Float3(
x.x * m.z.x + y.x * m.z.y + z.x * m.z.z,
x.y * m.z.x + y.y * m.z.y + z.y * m.z.z,
x.z * m.z.x + y.z * m.z.y + z.z * m.z.z,
)
)

operator fun times(v: Float3): Float3 {
val t = transpose(this)
return Float3(dot(t.x, v), dot(t.y, v), dot(t.z, v))
}
operator fun times(v: Float3) = Float3(
x.x * v.x + y.x * v.y + z.x * v.z,
x.y * v.x + y.y * v.y + z.y * v.z,
x.z * v.x + y.z * v.y + z.z * v.z,
)

fun toFloatArray() = floatArrayOf(
x.x, y.x, z.x,
Expand Down Expand Up @@ -315,20 +329,39 @@ data class Mat4(
operator fun times(v: Float) = Mat4(x * v, y * v, z * v, w * v)
operator fun div(v: Float) = Mat4(x / v, y / v, z / v, w / v)

operator fun times(m: Mat4): Mat4 {
val t = transpose(this)
return Mat4(
Float4(dot(t.x, m.x), dot(t.y, m.x), dot(t.z, m.x), dot(t.w, m.x)),
Float4(dot(t.x, m.y), dot(t.y, m.y), dot(t.z, m.y), dot(t.w, m.y)),
Float4(dot(t.x, m.z), dot(t.y, m.z), dot(t.z, m.z), dot(t.w, m.z)),
Float4(dot(t.x, m.w), dot(t.y, m.w), dot(t.z, m.w), dot(t.w, m.w))
)
}
operator fun times(m: Mat4) = Mat4(
Float4(
x.x * m.x.x + y.x * m.x.y + z.x * m.x.z + w.x * m.x.w,
x.y * m.x.x + y.y * m.x.y + z.y * m.x.z + w.y * m.x.w,
x.z * m.x.x + y.z * m.x.y + z.z * m.x.z + w.z * m.x.w,
x.w * m.x.x + y.w * m.x.y + z.w * m.x.z + w.w * m.x.w,
),
Float4(
x.x * m.y.x + y.x * m.y.y + z.x * m.y.z + w.x * m.y.w,
x.y * m.y.x + y.y * m.y.y + z.y * m.y.z + w.y * m.y.w,
x.z * m.y.x + y.z * m.y.y + z.z * m.y.z + w.z * m.y.w,
x.w * m.y.x + y.w * m.y.y + z.w * m.y.z + w.w * m.y.w,
),
Float4(
x.x * m.z.x + y.x * m.z.y + z.x * m.z.z + w.x * m.z.w,
x.y * m.z.x + y.y * m.z.y + z.y * m.z.z + w.y * m.z.w,
x.z * m.z.x + y.z * m.z.y + z.z * m.z.z + w.z * m.z.w,
x.w * m.z.x + y.w * m.z.y + z.w * m.z.z + w.w * m.z.w,
),
Float4(
x.x * m.w.x + y.x * m.w.y + z.x * m.w.z + w.x * m.w.w,
x.y * m.w.x + y.y * m.w.y + z.y * m.w.z + w.y * m.w.w,
x.z * m.w.x + y.z * m.w.y + z.z * m.w.z + w.z * m.w.w,
x.w * m.w.x + y.w * m.w.y + z.w * m.w.z + w.w * m.w.w,
)
)

operator fun times(v: Float4): Float4 {
val t = transpose(this)
return Float4(dot(t.x, v), dot(t.y, v), dot(t.z, v), dot(t.w, v))
}
operator fun times(v: Float4) = Float4(
x.x * v.x + y.x * v.y + z.x * v.z+ w.x * v.w,
x.y * v.x + y.y * v.y + z.y * v.z+ w.y * v.w,
x.z * v.x + y.z * v.y + z.z * v.z+ w.z * v.w,
x.w * v.x + y.w * v.y + z.w * v.z+ w.w * v.w
)

fun toFloatArray() = floatArrayOf(
x.x, y.x, z.x, w.x,
Expand Down
46 changes: 46 additions & 0 deletions src/test/kotlin/com/curiouscreature/kotlin/math/MatrixTest.kt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,8 +19,54 @@ package com.curiouscreature.kotlin.math
import org.junit.Assert
import org.junit.Test
import kotlin.test.assertEquals
import kotlin.test.assertNotEquals

class MatrixTest {
@Test
fun `Mat2 multiplication`() {
val a = Mat2.of(1.0f, 2.0f, 3.0f, 4.0f)
val b = Mat2.of(2.0f, 0.0f, 1.0f, 2.0f)
assertEquals(
Mat2.of(4.0f, 4.0f, 10.0f, 8.0f),
a * b
)
}

@Test
fun `Mat3 multiplication`() {
val a = Mat3.of(1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f, 7.0f, 8.0f, 9.0f)
val b = Mat3.of(2.0f, 0.0f, 1.0f, 2.0f, 3.0f, 1.0f, 2.0f, 0.0f, 1.0f)
assertEquals(
Mat3.of(12.0f, 6.0f, 6.0f, 30.0f, 15.0f, 15.0f, 48.0f, 24.0f, 24.0f),
a * b
)
}

@Test
fun `Mat4 multiplication`() {
val a = Mat4.of(
1.0f, 2.0f, 3.0f, 4.0f,
5.0f, 6.0f, 7.0f, 8.0f,
9.0f, 10.0f, 11.0f, 12.0f,
13.0f, 14.0f, 15.0f, 16.0f,
)
val b = Mat4.of(
2.0f, 0.0f, 1.0f, 2.0f,
1.0f, 1.0f, 2.0f, 0.0f,
2.0f, 1.0f, 2.0f, 2.0f,
0.0f, 1.0f, 1.0f, 2.0f,
)
assertEquals(
Mat4.of(
10.0f, 9.0f, 15.0f, 16.0f,
30.0f, 21.0f, 39.0f, 40.0f,
50.0f, 33.0f, 63.0f, 64.0f,
70.0f, 45.0f, 87.0f, 88.0f
),
a * b
)
}

@Test
fun `Mat3 identity`() {
assertEquals(
Expand Down

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