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Member Since 18 Dec 2002
Offline Last Active Yesterday, 06:55 AM

#5280049 Registry Entry Locator

Posted by Nik02 on 07 March 2016 - 01:05 PM

MSDN is Microsoft's official documentation :D

#5280015 Having problems with 3D pipeline

Posted by Nik02 on 07 March 2016 - 08:30 AM

World space is too early - consider that the camera transformation can (and likely will) rotate the geometry so that faces which were "backfacing" (if that even makes sense without a camera) are no longer oriented in their original directions. Projection can also affect the orientation of the faces with regard to the screen. Backface culling should be done, at the earliest, after projection.

#5278653 How to clear this offset bit?

Posted by Nik02 on 29 February 2016 - 02:16 AM

You could verify the function by reading the documentation of the bitwise operators used therein, and testing it by feeding various values to it and comparing the returned values with known, expected values. It would also be a good chance to learn unit testing.


It is dangerous to use copy/pasted code in production projects, if you don't understand what it does. When stuff breaks, it is your fault, whether or not you understand why.

#5278045 HLSL SM3 Loop into a 1280x720 sampler texture

Posted by Nik02 on 25 February 2016 - 04:13 AM

256x256 does fit within your hardware's capabilities. Still, 65536 samples per pixel is a very large number.

Depending on what you're trying to do, you could use mip-mapping to downsample your source texture so that you'd drastically reduce the amount of samples needed. Of course, this sacrifices a little bit of precision, but you would gain a lot of performance in return.

#5277240 vertex shader useless when using geometry shader?

Posted by Nik02 on 21 February 2016 - 01:27 AM

Consider that the GPU can usually cache the output of the vertex shader, but not the geometry shader. This is because very little can be assumed about GS output in advance.

#5275915 Draw arc from 2 points and radius

Posted by Nik02 on 16 February 2016 - 08:26 AM

See the attached file.


Consider that n1 is the normalized vector from the center to the arc start point p1. Its tangent t1 with respect to the circle is simply n1 rotated 90 degrees. If you need to "place" the tangent vector, move it to start it from the arc point. However, for measuring the screen-space angle of it, you don't have to offset it.


angleOfTangent1 = atan2 (t1.x, t1.y)


Since you calculate the n1 already, you can find the angle of the tangent vector by swapping the x and y components of the normal n1 (thus implicitly performing the 90deg rotation), and put them to the atan2.


You can find the t2 and its angle exactly the same way.


Note that common implementations of atan2 return the angle in radians. 90 degrees is pi/2 radians. Also, atan2 is usually a helper layer on top of atan, that considers if either or both components are zero or negative, and adjusts the return value accordingly to arrive to a correct angle across the full circle. Atan, by itself, would only make sense when both parameters are positive.

Attached Thumbnails

  • tangents.jpg

#5274238 Hi there. Please read. Many thanks.

Posted by Nik02 on 04 February 2016 - 08:20 AM

If you don't have the skills to develop the game prototype yourself, you'll have to pay for other people to develop it, or have such an impressive portfolio that you attract people to work for free initially, with the promise of future profits.


Professionals usually get the job done, but you generally need to pay at least something up front, because their livelihood is tied to the work. Some developers may work initially for free, but if you don't promise anything concrete, you do run into the risk of losing them without notice; they are not obligated to work for you, because you are not obligated to pay for them.


Depending on which of these is your approach, you could post in "help wanted" (if seeking free help) or "classifieds" (if seeking professional help for a fee).


Finally, everyone has ideas. Even if you have the greatest game idea ever, it is the execution of the idea that matters.

#5273806 How find sample positions in mulisampling rendering?

Posted by Nik02 on 02 February 2016 - 01:50 AM

MJP's approach works even when GetSamplePosition is not available or applicable.

#5272822 Maximum image size of a WriteableBitmap?

Posted by Nik02 on 27 January 2016 - 06:07 AM

It is very possible to load the compressed files to memory and unpack them when you need to display them. Simply load them to byte vectors and when you need the Bitmap object from the data, initialize that from memory instead of from a file.


Note that scroll viewer virtualization (as in not keeping all items in memory) is a very common performance optimization technique in data-heavy user interfaces.


In combination with the aforementioned things, you could use an alternative PNG library that lets you specify the rectangle to load from the image, while not consuming the memory for the rest of the image. The format itself makes this possible, but I don't know specific libraries off the top of my head that can achieve this.  

#5272352 Going 64-bit, can't use Jet4 any more :(

Posted by Nik02 on 23 January 2016 - 07:37 AM

Also, consider replacing the Jet engine with SQL Server :)

#5272351 Going 64-bit, can't use Jet4 any more :(

Posted by Nik02 on 23 January 2016 - 07:33 AM

If Ace12 (or other alternative libraries) is not a viable path, you could separate the data access layer to its own process, and use some kind of inter-process communication mechanism to call it.

Windows offers several options for this; RPC, TCP or UDP (sockets), named pipes and shared memory files come to mind immediately. All of these allow 32- and 64-bit processes to communicate with each other.

#5270346 Draw without Buffers

Posted by Nik02 on 10 January 2016 - 02:36 AM

IIRC you don't have to set the buffers to null. Having no input layout means that the device won't try to access the buffers anyway.

#5266518 Your development workflow

Posted by Nik02 on 15 December 2015 - 12:10 PM

While (task = tasks.pop()) task.perform();

#5266053 C# Color Wheel

Posted by Nik02 on 12 December 2015 - 01:20 PM

Please find attached a sample which plots hue and saturation over x and y. Took half an hour to make it.


All and any improvement is left as an exercise to the reader smile.png


The code included herein is a C# project with .net 4.5.1 Windows Forms target. Should open in Visual Studio 2013 or later.


I was lazy with the HSL->RGB conversion and ported it from a StackOverflow article because it was more elegant than my old code. Link is in the source.

Attached Files

#5265940 C# Color Wheel

Posted by Nik02 on 11 December 2015 - 04:00 PM

A good starting point would be to just draw a color wheel to a window.


If you're using Windows Forms, you can use a Bitmap object to draw the graphic. You can get access to the image pixels and fill them yourself.


Since Bitmap is usually represented as RGB(a) values, you would probably find RGB<->HSL conversion functions useful. A simple HSL to RGB function divides the circle into six sectors and performs linear interpolation over the nearest sector to the hue angle as triangle. Saturation is simply linear interpolation between gray and the found hue, and lightness is interpolation between black, the color and white.


The "wheel" is a function of the angle and the distance from the center point. You can use atan (or atan2) to find an angle of a pixel relative to the center of the bitmap. This angle would be the hue angle parameter (as described in the previous paragraph). Lightness or saturation, could be the Euclidean distance of the pixel from the center. Either one could also be represented as a separate slider, because you cannot represent all three dimensions (h, s and l) in the same 2d area.


When you manage to draw the wheel, getting the RGB value given a clicked HSL point becomes simply evaluating the HSL to RGB conversion function at the clicked point. The restrictions that you mention can be implemented by simply restricting the selected parameters to given ranges.


The actual coding takes about half a day to a day, if you understand the concepts. Googling will readily find RGB-HSL conversion functions as well as the atan and distance functions, if they are not familiar. The .net reference documentation includes the Bitmap class documentation, which explains how to fill a bitmap manually in memory (as opposed to loading it from a file).