How to deal with 1D Textures?

[tomb18]

Hi, I'm having great success with your c# libraries. I am stuck on something though. I have a heightmap where I need the heights colored according to a gradient I created. This is

        //here is the texture 
        myTextureData[0].X = 0x00;      //blue
        myTextureData[0].Y = 0x00;
        myTextureData[0].Z = 0xFF;
        myTextureData[0].W = 0xFF;

        myTextureData[0].X = 0xFF;      //yellow
        myTextureData[0].Y = 0xFF;
        myTextureData[0].Z = 0x00;
        myTextureData[0].W = 0xFF;

        myTextureData[0].X = 0xFF;      //red
        myTextureData[0].Y = 0x00;
        myTextureData[0].Z = 0x00;
        myTextureData[0].W = 0xFF;

I want to feed this to a fragment shader so that colors are assigned to my vertices. COuld you please give a hint as to how I would accomplish this? I understand I do not need texture coordinates defined for this. Thanks a bunch!

[tomb18]

Hi, I realize that the above is incorrect. What I am trying to do is create a 1D texture. So I have this: Texel[] mytexturedata = { new Texel() { r = 0x00, g = 0xFF, b = 0x00, a = 0xFF }, // Green new Texel() { r = 0xFF, g = 0xFF, b = 0x00, a = 0xFF }, // Yellow new Texel() { r = 0xFF, g = 0x00, b = 0x00, a = 0xFF } // Red }; I now need to do all of the opengl bindings. However in your tutorial you only show creating a texture based on a bitmap. This will not work here. So I have tried the following:

        var test = Gl.GenTexture();
        Gl.BindTexture(TextureTarget.Texture1DArray, test);

But my guess is that that is nowhere close to what I need to do. Could you please help out here? Thanks

[tomb18]

I have a complete example on StackOverflow. Here is the link: http://stackoverflow.com/questions/41644191/coloring-a-heightmap-with-1d-texture-in-c-sharp-and-opengl Please help!! You are the only person out there that knows your libraries and gives us examples in C#.

[giawa]

Hey tomb18,

Sorry for the delay in getting back to you. This got completely lost in my e-mail. Did you end up having any luck with this? You should be able to load a 1 dimensional texture into OpenGL no problem using the normal Texture class. You can then just address the texture using normal UV mapping (using only either the U or the V). You could base the U or V off the height data that comes from your vertex shader (I'm assuming this would be the y component).

If you truly want to use a 1 dimensional texture target then you will have to avoid the Texture class and do what you have suggested (Texture1D).

Cheers

[giawa]

Hey tomb18,

Please re-open this issue if you're still having issues. I'm going to close it for now.

[tomb18]

Hi I ended up using a 2D texture just as easy. BTW, using your tutorials and libraries and a lot of trial and error I wrote this:

https://www.youtube.com/watch?v=AwB-4OycS6o

It uses only 1 open GL call every time it plots the heightMap. The data comes from a fast fourier transform of 2048 points 10 times a second.

I wish I knew C++, I’ve only used C#. It makes it tough to find examples that make sense but your libraries helped me through it.

thanks, Tom

From: giawa Sent: Thursday, March 16, 2017 7:01 PM To: giawa/opengl4csharp Cc: tomb18 ; Author Subject: Re: [giawa/opengl4csharp] How to deal with 1D Textures? (#9)

Hey tomb18,

Sorry for the delay in getting back to you. This got completely lost in my e-mail. Did you end up having any luck with this? You should be able to load a 1 dimensional texture into OpenGL no problem using the normal Texture class. You can then just address the texture using normal UV mapping (using only either the U or the V). You could base the U or V off the height data that comes from your vertex shader (I'm assuming this would be the y component).

If you truly want to use a 1 dimensional texture target then you will have to avoid the Texture class and do what you have suggested (Texture1D).

Cheers

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[giawa]

Hey tomb18,

That looks awesome! I use the fourier transform all of the time at work, so this is really neat to see! I'm glad you were able to get it working, and sorry I wasn't able to help much when you were actively working on it. Please feel free to open any new issues if you run into bugs/issues or want to ask a question.

Take care