64 lines
2.0 KiB
Markdown
64 lines
2.0 KiB
Markdown
# orx-integral-image
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CPU and GPU-based implementation for integral images (summed area tables)
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#### Usage
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```
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val image = colorBuffer( ... )
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image.shadow.download()
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val integralImage = IntegralImage.fromColorBufferShadow(image.shadow)
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// -- the sum for a given area can be queried using
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val sum = integralImage.sum(IntRectangle(20, 20, 100, 100))
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```
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## Fast Integral Image
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Since v0.0.20 orx-integral-image comes with `FastIntegralImage` which calculates integral images fully on the GPU.
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```kotlin
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import org.openrndr.application
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import org.openrndr.color.ColorRGBa
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import org.openrndr.draw.*
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import org.openrndr.extra.integralimage.*
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fun main(args: Array<String>) = application {
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configure {
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width = 1024
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height = 1024
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}
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program {
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val fii = FastIntegralImage()
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val target = colorBuffer(1024, 512, 1.0, ColorFormat.RGBa, ColorType.FLOAT32)
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val rt = renderTarget(1024, 512) {
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colorBuffer()
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}
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extend {
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drawer.background(ColorRGBa.PINK)
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drawer.isolatedWithTarget(rt) {
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drawer.ortho(rt)
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drawer.background(ColorRGBa.BLACK)
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drawer.fill = ColorRGBa.PINK.shade(1.0)
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drawer.circle(mouse.position, 128.0)
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}
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fii.apply(rt.colorBuffer(0),target)
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// -- here we sample from the integral image
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drawer.shadeStyle = shadeStyle {
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fragmentTransform = """
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float w = 128.0;
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vec2 step = 1.0 / textureSize(image, 0);
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vec4 t11 = texture(image, va_texCoord0 + step * vec2(w,w));
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vec4 t01 = texture(image, va_texCoord0 + step * vec2(-w,w));
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vec4 t00 = texture(image, va_texCoord0 + step * vec2(-w,-w));
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vec4 t10 = texture(image, va_texCoord0 + step * vec2(w,-w));
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x_fill = (t11 - t01 - t10 + t00) / (w*w);
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""".trimIndent()
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}
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drawer.image(target)
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}
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}
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}
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```
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