如何在 PyOpenGL 中将 png 图像作为图像叠加层？

Question

我正在使用 PyOpenGL 制作游戏，并希望将一些图像作为一些叠加层（例如，暂停按钮）在屏幕上显示。我该怎么做？

我尝试过使用glBitmap()，但它不起作用。

这就是我所拥有的：

pauseimg = pygame.image.load(path + "pause.png").convert_alpha()
def blit_image(x,y,w,h,img,r,g,b):
    glColor3f(r,g,b)
    glWindowPos2f(x,y)
    glBitmap(w,h,0,0,0,0,img)
blit_image(300,300,313,115,pauseimg,1,1,1)

我希望它会 blit 图像，但它却抛出了异常：

Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/OpenGL/latebind.py", line 41, in __call__
    return self._finalCall( *args, **named )
TypeError: 'NoneType' object is not callable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File ".py", line 438, in <module>
    blit_image(300,300,313,115,pauseimg,1,1,1)
  File ".py", line 135, in blit_image
    glBitmap(w,h,0,0,0,0,img)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/OpenGL/latebind.py", line 45, in __call__
    return self._finalCall( *args, **named )
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/OpenGL/wrapper.py", line 675, in wrapperCall
    pyArgs = tuple( calculate_pyArgs( args ))
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/OpenGL/wrapper.py", line 436, in calculate_pyArgs
    yield converter(args[index], self, args)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/OpenGL/converters.py", line 135, in __call__
    return self.function( incoming )
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/OpenGL/arrays/arraydatatype.py", line 149, in asArray
    return cls.getHandler(value).asArray( value, typeCode or cls.typeConstant )
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/OpenGL/arrays/arraydatatype.py", line 53, in __call__
    typ.__module__, type.__name__, repr(value)[:50]
TypeError: ('No array-type handler for type pygame.type (value: <Surface(313x114x32 SW)>) registered', <OpenGL.converters.CallFuncPyConverter object at 0x111a720b8>)```

Answer 1

glBitmap 无法绘制格式为GL_RGBA8 的位图，因为缓冲区被视为格式为GL_COLOR_INDEX 的缓冲区（参见glTexImage2D）

参见OpenGL 4.6 API Compatibility Profile Specification - 14.8 Bitmaps，第 579 页：

像多边形图案一样，位图是根据 第 18.1 节中给出的 DrawPixels 程序；好像宽度和高度 传递给该命令的分别等于 w 和 h，类型为 BITMAP， 格式为 COLOR_INDEX。

---

如果你想绘制一个 RGBA trexutre，那么你必须创建一个 butte 数组缓冲区。这可以通过NumPy实现：

raw_data = img.get_buffer().raw
data = numpy.fromstring(raw_data, numpy.uint8)

通过glTexImage2D创建纹理对象：

bitmap_tex = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, bitmap_tex)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,w,h,0,GL_BGRA,GL_UNSIGNED_BYTE,data)

并通过Quads - Primitive绘制纹理：

glEnable(GL_TEXTURE_2D)
glBegin(GL_QUADS)
glTexCoord2f(0, 1)
glVertex2f(x, y)
glTexCoord2f(1, 1)
glVertex2f(x+w, y)
glTexCoord2f(1, 0)
glVertex2f(x+w, y+h)
glTexCoord2f(0, 0)
glVertex2f(x, y+h)
glEnd()
glDisable(GL_TEXTURE_2D)

如果纹理是透明的，那么你必须激活Blending。
该功能可以实现如下：

bitmap_tex = None
def blit_image(x,y,img,r,g,b):
    global bitmap_tex

    # get texture data
    w,h = img.get_size()
    raw_data = img.get_buffer().raw
    data = numpy.fromstring(raw_data, numpy.uint8)

    # create texture object
    if bitmap_tex == None:
      bitmap_tex = glGenTextures(1)
    glBindTexture(GL_TEXTURE_2D, bitmap_tex)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
    glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,w,h,0,GL_BGRA,GL_UNSIGNED_BYTE,data)

    # save and set model view and projection matrix
    glMatrixMode(GL_PROJECTION)
    glPushMatrix()
    glLoadIdentity()
    glOrtho(0, display[0], 0, display[1], -1, 1)
    glMatrixMode(GL_MODELVIEW)
    glPushMatrix()
    glLoadIdentity()

    # enable blending
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
    glEnable(GL_BLEND)

    # draw textured quad
    glColor3f(r,g,b)

    glEnable(GL_TEXTURE_2D)
    glBegin(GL_QUADS)
    glTexCoord2f(0, 1)
    glVertex2f(x, y)
    glTexCoord2f(1, 1)
    glVertex2f(x+w, y)
    glTexCoord2f(1, 0)
    glVertex2f(x+w, y+h)
    glTexCoord2f(0, 0)
    glVertex2f(x, y+h)
    glEnd()
    glDisable(GL_TEXTURE_2D)

    # restore matrices
    glMatrixMode(GL_PROJECTION)
    glPopMatrix()
    glMatrixMode(GL_MODELVIEW)
    glPopMatrix()

    # disable blending
    glDisable(GL_BLEND)

pauseimg = pygame.image.load(path + "pause.png").convert_alpha()
blit_image(300,300,pauseimg,1,1,1)