Home/ Questions/Q 117827
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-11T03:23:52+00:00

I’m stuck at not being able to map texture to a square in openGLES.

  • 0

I’m stuck at not being able to map texture to a square in openGLES. I’m trying to display a jpg image on the screen, and in order for me to do that, I draw a square that I want to then map image onto. However all I get as an output is a white square. I don’t know what am I doing wrong. And this problem is preventing me from moving forward with my project. I’m using Managed OpenGL ES wrapper for Windows Mobile. I verified that the texture is loading correctly, but I can’t apply it to my object. I uploaded sample project that shows my problem here. You would need VS2008 with Windows Mobile 6 SDK to be able to run it. I’m also posting the code of the Form that renders and textures an object here. Any suggestions would be much appreciated, since I’ve been stuck on this problem for a while, and I can’t figure out what am I doing wrong.

    public partial class Form1 : Form {     [DllImport('coredll')]     extern static IntPtr GetDC(IntPtr hwnd);      EGLDisplay myDisplay;     EGLSurface mySurface;     EGLContext myContext;      public Form1()     {         InitializeComponent();         myDisplay = egl.GetDisplay(new EGLNativeDisplayType(this));          int major, minor;         egl.Initialize(myDisplay, out major, out minor);          EGLConfig[] configs = new EGLConfig[10];         int[] attribList = new int[]          {              egl.EGL_RED_SIZE, 5,              egl.EGL_GREEN_SIZE, 6,              egl.EGL_BLUE_SIZE, 5,              egl.EGL_DEPTH_SIZE, 16 ,              egl.EGL_SURFACE_TYPE, egl.EGL_WINDOW_BIT,             egl.EGL_STENCIL_SIZE, egl.EGL_DONT_CARE,             egl.EGL_NONE, egl.EGL_NONE          };          int numConfig;         if (!egl.ChooseConfig(myDisplay, attribList, configs, configs.Length, out numConfig) || numConfig < 1)             throw new InvalidOperationException('Unable to choose config.');          EGLConfig config = configs[0];         mySurface = egl.CreateWindowSurface(myDisplay, config, Handle, null);         myContext = egl.CreateContext(myDisplay, config, EGLContext.None, null);          egl.MakeCurrent(myDisplay, mySurface, mySurface, myContext);         gl.ClearColor(0, 0, 0, 0);         InitGL();     }      void InitGL()     {         gl.ShadeModel(gl.GL_SMOOTH);         gl.ClearColor(0.0f, 0.0f, 0.0f, 0.5f);         gl.BlendFunc(gl.GL_SRC_ALPHA, gl.GL_ONE_MINUS_SRC_ALPHA);         gl.Hint(gl.GL_PERSPECTIVE_CORRECTION_HINT, gl.GL_NICEST);     }      public unsafe void DrawGLScene()     {         gl.MatrixMode(gl.GL_PROJECTION);         gl.LoadIdentity();         gl.Orthof(0, ClientSize.Width, ClientSize.Height, 0, 0, 1);         gl.Disable(gl.GL_DEPTH_TEST);          gl.MatrixMode(gl.GL_MODELVIEW);         gl.LoadIdentity();          Texture myImage;         Bitmap Image = new Bitmap(@'\Storage Card\Texture.jpg');         using (MemoryStream ms = new MemoryStream())         {             Image.Save(ms, System.Drawing.Imaging.ImageFormat.Bmp);             myImage = Texture.LoadStream(ms, false);         }          float[] rectangle = new float[] {                 0, 0,                 myImage.Width, 0,                 0,  myImage.Height,                 myImage.Width,  myImage.Height             };          float[] texturePosition = new float[] {                 0, 0,                 myImage.Width, 0,                 0,  myImage.Height,                 myImage.Width,  myImage.Height             };          //Bind texture         gl.BindTexture(gl.GL_TEXTURE_2D, myImage.Name);         gl.TexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MIN_FILTER, gl.GL_LINEAR);         gl.TexParameteri(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MAG_FILTER, gl.GL_LINEAR);         gl.EnableClientState(gl.GL_TEXTURE_COORD_ARRAY);         gl.EnableClientState(gl.GL_VERTEX_ARRAY);          //draw square and texture it.         fixed (float* rectanglePointer = &rectangle[0], positionPointer = &texturePosition[0])         {             gl.TexCoordPointer(2, gl.GL_FLOAT, 0, (IntPtr)positionPointer);             gl.VertexPointer(2, gl.GL_FLOAT, 0, (IntPtr)rectanglePointer);             gl.DrawArrays(gl.GL_TRIANGLE_STRIP, 0, 4);         }          gl.DisableClientState(gl.GL_TEXTURE_COORD_ARRAY);         gl.DisableClientState(gl.GL_VERTEX_ARRAY);      }      protected override void OnPaintBackground(PaintEventArgs e)     {      }      protected override void OnPaint(PaintEventArgs e)     {         base.OnPaint(e);         gl.Clear(gl.GL_COLOR_BUFFER_BIT);          DrawGLScene();         egl.SwapBuffers(myDisplay, mySurface);         gl.Clear(gl.GL_COLOR_BUFFER_BIT);     }      protected override void OnClosing(CancelEventArgs e)     {         if (!egl.DestroySurface(myDisplay, mySurface))             throw new Exception('Error while destroying surface.');         if (!egl.DestroyContext(myDisplay, myContext))             throw new Exception('Error while destroying context.');         if (!egl.Terminate(myDisplay))             throw new Exception('Error while terminating display.');         base.OnClosing(e);     } }
Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. You need to enable texturing:

    glEnable( GL_TEXTURE_2D );

    before rendering the square.

    • 0