About Point Cloud Example

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Learning Objectives

This openFrameworks Example is demonstrates how to create a [point cloud] (https://en.wikipedia.org/wiki/Point_cloud) of data points in 3d space from an image, and represented by a mesh to represent the exterior surface.

After studying this example, you will understand how to

In the code, pay attention to:

• ofSetVerticalSync to synchronize the redraw of the screen to the vertical refresh of your screen
• setting the mode of the mesh to use points with mesh.setMode(OF_PRIMITIVE_POINTS);
• Loading the image using img.load and then examining the pixels in the image by looping through the grid of pixels and getting color with img.getColor(x,y)
• Utilizing the alpha value of the current pixel from the image to determine the z space coordinate and mapping it to a good depth rangefloat z = ofMap(cur.a, 0, 255, -300, 300);
• ofEnableDepthTest to ensure rendering happens according to z-depth rather than draw order.
• glEnable(GL_POINT_SMOOTH) to make the points round
• glPointSize(3) to the points bigger
• ofScale(2,-2,2) to flip the y axis and zoom the item in
• ofRotateY(90) to rotate on the y axis so we are looking at the face from the side.
• cam.begin use of an ofEasyCam to render the scene

Expected Behavior

When launching this app, you should see

• A mesh that uses points to draw the exterior surface of the side of a face

Instructions for use:

• Try pressing the various keys to alter the drawing state. Refer to the overlay on the application to know which keys to press.