Edit data in a float buffer

jeremydouglass · November 10, 2019, 12:33am

@sash – this question is listed in p5.js – can you just confirm that you are only using Processing (Java) for this project?

Have you looked at the RecordPointCloud example?

github.com

ThomasLengeling/KinectPV2/blob/master/KinectPV2/examples/RecordPointCloud/RecordPointCloud.pde

/*
Thomas Sanchez Lengeling.
 http://codigogenerativo.com/
 
 KinectPV2, Kinect for Windows v2 library for processing
 
 How to record Point Cloud Data and store it in several obj files.
 Record with 'r'
 */

import java.util.ArrayList;
import java.nio.*;
import KinectPV2.*;

KinectPV2 kinect;

PGL pgl;
PShader sh;

int  vertLoc;

This file has been truncated. show original

…and at the available methods on a FloatBuffer for inspection?

https://docs.oracle.com/javase/7/docs/api/java/nio/FloatBuffer.html

It sounds like you just want to replace those values (which I believe are in ordered triples?) with a subsampled list of values, so that

0,1,2, 3,4,5, 6,7,8, 9,10,11

becomes

0,1,2, 6,7,8

Is that right?

I think (?) that the Kinect library grabs raw data and puts it in the float buffer here:

github.com

ThomasLengeling/KinectPV2/blob/master/Build_libs/KinectPV2_Eclipse/src/KinectPV2/Device.java#L473-L483


	 * Get Point Cloud Depth Map as FloatBuffer, transform to a float array with .array(), or get values with get(index)
	 *
	 * @return FloatBuffer
	 */
	public FloatBuffer getPointCloudDepthPos() {
		float[] pcRawData = jniGetPointCloudDeptMap();
		pointCloudDepthPos.put(pcRawData, 0, WIDTHDepth * HEIGHTDepth * 3);
		pointCloudDepthPos.rewind();


		return pointCloudDepthPos;
	}

…which it originally dumps from JNI here:

github.com

ThomasLengeling/KinectPV2/blob/master/Build_libs/KinectPV2_vc2012/KinectLib_V2.0/KinectV2_JNI_Device.cpp#L639-L659


* Class:     KinectPV2_Device
* Method:    jniGetPointCloudDeptMap
* Signature: ()[F
*/
JNIEXPORT jfloatArray JNICALL Java_KinectPV2_Device_jniGetPointCloudDeptMap
(JNIEnv * env, jobject obj)
{
	jclass cls = env->GetObjectClass(obj);
	jfieldID fid = env->GetFieldID(cls, "ptr", "J");
	KinectPV2::Device * kinect = (KinectPV2::Device *) env->GetLongField(obj, fid);


	jfloat * pFloat = (jfloat *)kinect->JNI_pointCloudPosData();


	jfloatArray buffer = env->NewFloatArray(frame_size_depth * 3);
	env->SetFloatArrayRegion(buffer, 0, frame_size_depth * 3, pFloat);




	env->DeleteLocalRef(cls);


	return buffer;
}

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Edit data in a float buffer

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