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Soundbomber's picture

Texture sizes

Posted Monday, 8 June, 2009 - 08:32 by Soundbomber in

How do I scale the size of a texture?
I have the correct mapping of my texture but it is tiny, how can I make the size bigger?

        Dim iTextureID As Integer
       Dim oData As Imaging.BitmapData = Nothing
       Dim bmp As Bitmap = Nothing
       If m_bUseTextures Then
            oGL.Hint(HintTarget.PerspectiveCorrectionHint, HintMode.Nicest)
            oGL.GenTextures(1, iTextureID)
            oGL.BindTexture(TextureTarget.Texture2D, iTextureID)
            oGL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, _
                TextureMinFilter.Linear)
            oGL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, _
                TextureMinFilter.Linear)
            oGL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, _
                TextureWrapMode.Repeat)
            oGL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, _
                TextureWrapMode.Repeat)
            bmp = My.Resources.resResources.old_steel_big
            oData = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), _
                Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb)
            oGL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, oData.Width, _
                oData.Height, 0, OpenTK.Graphics.PixelFormat.Bgra, PixelType.UnsignedByte, oData.Scan0)
            oGL.Enable(EnableCap.Texture2D)
            oGL.Enable(EnableCap.TextureGenS)
            oGL.Enable(EnableCap.TextureGenT)
            oGL.TexGen(TextureCoordName.S, TextureGenParameter.TextureGenMode, _
                TextureGenMode.EyeLinear)
            oGL.TexGen(TextureCoordName.T, TextureGenParameter.TextureGenMode, _
                TextureGenMode.EyeLinear)
        End If
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objarni's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 08:34 by objarni

Could you draw a screenshot of what you are trying to do?

Soundbomber's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 08:40 by Soundbomber

View1.png shows my object full size with the textures applied.
View2 shows a close up with many very small texture bitmaps instead of of one or two texture bitmaps drawn at full size and repeated.

AttachmentSize
View2.PNG241.04 KB
View1.PNG48.73 KB
objarni's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 08:51 by objarni

You should be able to multiply the texture matrix with a Scale matrix (0.1, 0.1, 0.1). At least that is my guess; I am not sure if the texture matrix is applied when you use TexGen functions, but I think so:

GL.MatrixMode(Texture);
GL.LoadIdentity();
GL.Scale(0.1, 0.1, 0.1); // or 10, 10, 10 I'm not sure which you want
GL.MatrixMode(ModelView);
Soundbomber's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 09:17 by Soundbomber

That worked a treat, but now the texture isn't rotating a with the view. It just appears to be always rendering at a fixed point.

objarni's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 09:31 by objarni

Are you using TexGen?

Soundbomber's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 09:41 by Soundbomber

Yes

martinsm's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 10:42 by martinsm

Don't use TexGen. Specify texture coordinates manually with glTexCoord - like you specify vertex coordinates with glVertex. Or if you use VA or VBO, then use glTexCoordPointer.

Soundbomber's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 10:45 by Soundbomber

I want to automatically generate my texture coords. My model is too complex to do it by hand.

objarni's picture

Re: Texture sizes

Posted Monday, 8 June, 2009 - 11:05 by objarni

TexGen + texture matrix scaling should be possible, see for example this PDF:

http://developer.nvidia.com/attach/6750