我得到白色纹理OpenGL

Question

I'm trying to draw a texture, but it is white :( I checked and the texture is 32 * 32 pixels.

Here is my code for drawing :

GL11.glBegin(GL11.GL_QUADS);
            GL11.glBindTexture(GL11.GL_TEXTURE_2D, Loader.textures.get(3).getTextureID());
            GL11.glVertex2f(n.getPosition().x * 40 + 3, n.getPosition().y * 40 + 3);
            GL11.glVertex2f(n.getPosition().x * 40 + 3, n.getPosition().y * 40 + 37);
            GL11.glVertex2f(n.getPosition().x * 40 + 37, n.getPosition().y * 40 + 37);
            GL11.glVertex2f(n.getPosition().x * 40 + 37, n.getPosition().y * 40 + 3);
            GL11.glBindTexture(GL11.GL_TEXTURE_2D, 0);
        GL11.glEnd();

And initializing OpenGL :

try {
            Display.setDisplayMode(new DisplayMode(WIDTH, HEIGHT)); 
            Display.create();
            Display.setTitle(title);
            glMatrixMode(GL_PROJECTION);
            glLoadIdentity();
            glOrtho(0, WIDTH, HEIGHT, 0, 1, -1);
            glMatrixMode(GL_MODELVIEW);
            glEnable(GL_TEXTURE_2D);
            glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
            glEnable(GL_BLEND);
            glEnable(GL_CULL_FACE);
            glCullFace(GL11.GL_BACK);
            glClearColor(0.25f, 0.25f, 0.25f, 1);
        } catch (LWJGLException e) {
            e.printStackTrace();
        }

        GL11.glViewport(0, 0, WIDTH, HEIGHT);
        lastFrameTime = getCurrentTime();

Help me, please!

Answer 1

You have to specify texture coordinates . I'm not sure about the exact syntax in your situation, but the resulting code should be similar to this:

GL11.glBegin(GL11.GL_QUADS);
    GL11.glBindTexture(GL11.GL_TEXTURE_2D, Loader.textures.get(3).getTextureID());
    GL11.glVertex2f(n.getPosition().x * 40 + 3, n.getPosition().y * 40 + 3);
    GL11.glTexCoord2f(0f, 0f);
    GL11.glVertex2f(n.getPosition().x * 40 + 3, n.getPosition().y * 40 + 37);
    GL11.glTexCoord2f(0f, 1f);
    GL11.glVertex2f(n.getPosition().x * 40 + 37, n.getPosition().y * 40 + 37);
    GL11.glTexCoord2f(1f, 1f);
    GL11.glVertex2f(n.getPosition().x * 40 + 37, n.getPosition().y * 40 + 3);
    GL11.glTexCoord2f(1f, 0f);
    GL11.glBindTexture(GL11.GL_TEXTURE_2D, 0);
GL11.glEnd();

Answer 2

You have two problems.

First, you cannot call glBindTexture within the boundary of glBegin/End . You call it before or afterwards:

GL11.glBindTexture(GL11.GL_TEXTURE_2D, loader.textures.get(3).getTextureID());
GL11.glBegin(GL11.GL_QUADS);
...

Second, you need to provide texture coordinates. These ought to be provided for each vertex. And you must provide the texture coordinate before calling glVertex :

GL11.glTexCoord2f(0.0, 0.0);
GL11.glVertex2f(n.getPosition().x * 40 + 3, n.getPosition().y * 40 + 3);
GL11.glTexCoord2f(0.0, 1.0);
GL11.glVertex2f(n.getPosition().x * 40 + 3, n.getPosition().y * 40 + 37);
GL11.glTexCoord2f(1.0, 1.0);
GL11.glVertex2f(n.getPosition().x * 40 + 37, n.getPosition().y * 40 + 37);
GL11.glTexCoord2f(1.0, 0.0);
GL11.glVertex2f(n.getPosition().x * 40 + 37, n.getPosition().y * 40 + 3);

Exactly which texture coordinates you want to use depends on exactly how you want to do the mapping.