3D-2D Perspective Mapping in Excel – part #2

31/01/2011

The first half of this presentation dealt with mapping a 3D scene onto a 2D surface which can be a computer screen, a projection screen or the retina of the eye. By doing so we preserve much of the feel of depth of the scene. Of course when we look at an picture we get only part of the feel of depth because our both eyes see the same image….

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3D-2D Perspective Mapping in Excel – part #1

31/01/2011

In computer graphics we often need to be able to display a three-dimensional image in two dimensions and preserve the perspective appearance. If we walk on a straight road, it appears that the road narrows with the distance. This is the perspective effect and it is a result of mapping a three-dimensional image on a two-dimensional surface (i.e. a computer monitor, a screen, or the retina of the eye). This tutorial…

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A Virtual Joystick – How Can You Make That ? – tutorial

31/01/2011

Hello everybody, this is a tutorial in which a virtual  Excel joystick controlled by mouse movements on a scatter chart has been demonstrated . While in operation, a macro updates the coordinates of the pointer in two spreadsheet cells. The two coordinates are then incorporated in formulas which limit the range of motion of the joystick. Just like a real device the stick head movement is confined within a square (with a side…

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Modeling a Three-Pendulum Harmonograph – tutorial: part #2

23/01/2011

Hi guys, here is the second part of a tutorial describing the matematical equations used in modeling a three-pendulum harmonograph (automatic drawing machine). It pertains to the second version of the model. This section describes the kinematic equations involved in the articulated linkage mechanism on the top of the table, the custom spreadsheet functions used in the model and some overall considerations about the partition of the spreadsheet.  This is an…

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Writing Excel User Defined Functions in VBA – part #2 – time stamping, concatenating date and text while maintaining the date format

19/01/2011

Hi Folks, there are many available built-in spreadsheet functions in Excel. Ocasionaly one might need to write a special custom function. This second short tutorial is an introduction to that.  Creating a “Time Stamp” function is presented as a first example after which a concatenation function between a custom formatted date and a string (text) is introduced. This last function came about from a question I was asked by a finance person at…

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Modeling a Three-Pendulum Harmonograph – tutorial: part #1

19/01/2011

Hi guys, here is the first part of a tutorial describing the matematical equations used in modeling a three-pendulum harmonograph (automatic drawing machine). It pertains to the second version of the model. This section refers only to the kinematic equations for the movement of three pendulums. A second section will be published later and it will describe the kinematic equations involved in the articulated linkage mechanism on the top of the table,…

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Three-Pendulum Harmonograph #2 – an improved version

16/01/2011

Hi! Here is an improved (faster and cleaner) version of the harmonograph. The worksheet has three different areas, the physical machine (a photo of the machine build out of wood by Karl Sims), the virtual machine (which is a 2D chart with a top view of a model showing the three pendulum ends, the drawing table, and the linkage mechanism which connects pendulum #1, pendulum #2 and the pencil) and the detailed curve area….

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Writing Excel User Defined Functions in VBA – part #1 – the distance function

14/01/2011

There are many available built-in spreadsheet functions in Excel. Ocasionaly one might need a very special custom function. This short tutorial is an introduction about how to write a user defined function which calculate the distance between two points in a cartesian plane. The topic will be continued and custom functions will occasionally be used in future models. We’d love to hear from you.

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Digital Clock Model – an Excel 2007 adaptation

07/01/2011

Hello!  Due to some incompatibility, I re-adjusted the old digital clock for the 2007 version of Excel. In Excel 2003 or earlier if you click on a chart point twice (with a certain delay between clicks) you can paste a picture and have the data point actually convert into that picture. In 2007 the same trick works but somehow the picture expands by something like 20%, which makes a lot of…

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