title: Triangle texture mapping OpenGL
body: <p>I am working on a project using the Marching Cubes algorithm and changing the data into a 3D model. Now I want to use texture mapping in OpenGL for my 3D model. I have tried a simple example to begin with, which maps a picture onto a triangle.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>int DrawGLScene(GLvoid)    // Here's Where We Do All The Drawing
  {
      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
      glLoadIdentity();                            // Reset The Current Matrix
      glTranslatef(1.0f,0.0f,-6.0f);               // Move Into The Screen 5 Units
      glRotatef(xrot,1.0f,0.0f,0.0f);              // Rotate On The X Axis
      glRotatef(yrot,0.0f,1.0f,0.0f);              // Rotate On The Y Axis
      glRotatef(zrot,0.0f,0.0f,1.0f);              // Rotate On The Z Axis
      glBindTexture(GL_TEXTURE_2D, texture[0]);    // Select Our Texture
      glBegin(GL_TRIANGLES);
  
      glTexCoord2f(0, 0); glVertex3f( -2,  0, -2 );
      glTexCoord2f(1, 0); glVertex3f(  2,  0, -2 );
      glTexCoord2f(0.5, 1); glVertex3f(  0,  2, -2 );
  
      glEnd();
  
      xrot+=0.3f;                             // X Axis Rotation
      yrot+=0.2f;                             // Y Axis Rotation
      zrot+=0.4f;                             // Z Axis Rotation
      return true;                            // Keep Going
  } 
  </code></pre>
  
  <p>Now the problem is that the picture does not map completely within the triangle, and the program cut the image for the triangle, so I am losing some part of my data.
  How can I  map the whole image into the triangle?</p>