OpenGL 位图程序只显示白色、黑色和黄色？

Question

我正在使用http://partow.net/programming/bitmap/index.html 和 OpenGL 上的库来制作在我的屏幕上加载位图的函数。图像加载但只显示黑色、白色和黄色。我在 Windows 7 上使用 Dev C++。这是我的代码：

void Load_Image(HDC hDC, string File_Name, int x_position, int y_position, int length, int height)
{     
bitmap_image image(File_Name);      // Open the bitmap
unsigned char red;
unsigned char green;
unsigned char blue;
restart:
image.get_pixel(x_position, y_position, red, green, blue);     // Get the red green and blue from x_position and y_position and store it in red green and blue. 
glBegin (GL_TRIANGLES);                                        // Make a pixel at x_position and y_position with red green and blue.
glColor3f (red, green, blue);
glVertex2f (-1 + 0.0015 * x_position, 1 - 0.003 * y_position);
glVertex2f (-1 + 0.0015 * x_position, 0.997 - 0.003 * y_position);
glVertex2f (-0.9985 + 0.0015 * x_position, 1 - 0.003 * y_position);
glEnd();
glBegin (GL_TRIANGLES);
glColor3f (red, green, blue);
glVertex2f (-1 + 0.0015 * x_position, 0.997 - 0.003 * y_position);
glVertex2f (-0.9985 + 0.0015 * x_position, 1 - 0.003 * y_position);
glVertex2f (-0.9985 + 0.0015 * x_position, 0.997 - 0.003 * y_position);
glEnd();
if (x_position==length)      // If x_position equals to length of bmp set x_position to 0 and add 1 to y_position.
{
if (y_position==height)      // If bmp is done loading go to done.
{
goto done;
}
x_position = 0;
y_position = y_position + 1;
}
x_position = x_position + 1;
goto restart;
done:         
SwapBuffers(hDC);            // Put it on the screen.
}

关于什么是错的任何想法？谢谢！

Answer 1

颜色值red, green,blue的类型unsigned char为 0..255。glColor然而，的浮点变体glColor3f期望输入值在 0..1 范围内。尝试使用glColor3ub()替代。

更新：我最初的答案建议，glColor3b()但它应该是 unsignedvariant glColor3ub()。