Symkortem's picture

ANother noob problem: More than one texture

Hi Communety!

I have a little noob Problem.
Sorry for that, but iam still learning.

In my Programm i want to draw many Quads, and every quad should get another bitmap as texture.
So i tried to change the code from "" for my needs.
But all quads have the same texture.

Can anybody help me pls, how can i assign different textures to the quads?

best regards


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puklaus's picture

When loading textures, keep every created textures ID in memory and
when rendering quads, change (bind) before rendering the wanted texture id:
GL.BindTexture(TextureTarget.Texture2D, textureID);

Symkortem's picture


First of all i load the bitmap.

bitmap = new Bitmap(@"Resources\Düne.JPG");

than i upload the texture

            GL.Hint(HintTarget.PerspectiveCorrectionHint, HintMode.Nicest);
            if(bitmapindex >0 && texture[bitmapindex-1] == 0)
                texture[bitmapindex-1] = GL.GenTexture();
                //GL.GenTextures(1, out texture[bitmapindex - 1]);
            BitmapData data = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height),
                ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
            GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba, data.Width, data.Height, 0,
                OpenTK.Graphics.PixelFormat.Bgra, PixelType.UnsignedByte, data.Scan0);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);

than i want to load/upload the second bitmap/texture.
same procedure.

after that, i want to draw 2 quads, which i have stored in a list.
in itemindex is stored, whether it is the first, or second texture
the first quad has itemindex = 0 and the 2nd has itemindex = 1

            if (itemlist.Count != 0)
                foreach (Item i in itemlist)
                    GL.BindTexture(TextureTarget.Texture2D, i.ItemIndex);
                    label2.Text = i.ItemIndex.ToString();
                    GL.TexCoord2(0f, 1f);
                    GL.Vertex3(i.Posx - 15, i.Posy - 15, i.Posz);
                    GL.TexCoord2(0f, 0f);
                    GL.Vertex3(i.Posx + 15, i.Posy - 15, i.Posz);
                    GL.TexCoord2(1f, 0f);
                    GL.Vertex3(i.Posx + 15, i.Posy + 15, i.Posz);
                    GL.TexCoord2(1f, 1f);
                    GL.Vertex3(i.Posx - 15, i.Posy + 15, i.Posz);

but now i have 2 quads with the same texture. and always the last one i have uploaded.

objarni's picture

BindTexture should be called before Begin.

Entropy's picture

I guess it's a personal preference, but I like to keep all my OpenGL texture/VBO/buffer/FBO handles in separate instances of fully OO classes. That way I might load a .png of a cow and a .png of a sheep into 2 Texture2D objects called, respecively, "cow" and "sheep", with nested draw methods (cow.Draw();, or maybe game.RenderFrame += sheep.Draw;).

Edit: corrected my terminology. Changed "classes" to "objects".

Symkortem's picture

Thats. That hint with the OO class was great...

now i just have to rewrite my game class.

thanks alot