80 lines
2.5 KiB
Kotlin
80 lines
2.5 KiB
Kotlin
package studio.rndnr.packture
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import org.openrndr.color.ColorRGBa
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import org.openrndr.draw.ColorBufferShadow
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import org.openrndr.shape.IntRectangle
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class IntegralImage(val width: Int, val height: Int, val integral: LongArray) {
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internal val maximum: Long
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get() = integral[integral.size - 1]
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companion object {
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fun fromColorBufferShadow(shadow: ColorBufferShadow, sampler: (ColorRGBa) -> Long = { (it.r * 255.0).toLong() }): IntegralImage {
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val integral = LongArray(shadow.colorBuffer.width * shadow.colorBuffer.height)
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val width = shadow.colorBuffer.width
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val height = shadow.colorBuffer.height
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for (i in integral.indices) {
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integral[i] = 0
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}
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for (y in 0 until height) {
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for (x in 0 until width) {
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val i = sampler(shadow.read(x, y))
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var i10: Long = 0
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if (x > 0)
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i10 = integral[x - 1 + y * width]
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var i01: Long = 0
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if (y > 0) {
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i01 = integral[x + (y - 1) * width]
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}
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var i11: Long = 0
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if (y > 0 && x > 0) {
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i11 = integral[x - 1 + (y - 1) * width]
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}
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integral[y * width + x] = i + i10 + i01 - i11
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}
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}
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return IntegralImage(width, height, integral)
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}
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}
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private fun clip(x: Int, left: Int, right: Int): Int {
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return Math.min(right, Math.max(left, x))
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}
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fun sum(area: IntRectangle): Long {
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return sum(area.x, area.y, area.x + area.width - 1, area.y + area.height - 1)
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}
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private fun sum(left: Int, top: Int, right: Int, bottom: Int): Long {
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var left = left
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var top = top
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var right = right
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var bottom = bottom
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top = clip(top, 0, height - 1)
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bottom = clip(bottom, 0, height - 1)
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left = clip(left, 0, width - 1)
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right = clip(right, 0, width - 1)
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val a = integral[left + top * width]
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val b = integral[right + top * width]
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val c = integral[right + bottom * width]
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val d = integral[left + bottom * width]
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return a + c - b - d
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}
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private fun average(left: Int, top: Int, right: Int, bottom: Int): Double {
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val area = ((right - left) * (bottom - top)).toDouble()
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return sum(left, top, right, bottom) / area
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}
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} |