使用 PyOpenGL 渲染纹理矩形

Question

我正在使用 PyOpenGL 开发一个项目，目前我正在尝试让 OpenGL 渲染一种启动画面。我决定的解决方案是绘制一个带纹理的二维矩形。不幸的是，似乎无论我做什么，都没有绘制任何东西，我只是得到一个黑屏（所以我猜想绘制了一些东西，否则它将是一个透明的窗口，但这绝对不是我想要的）。这是我的班级的相关代码：

class ClassThing:
    def __init__(self):
        self.Splash = True
        glutInit(sys.argv)

    def TexFromPNG(self, filename):
        img = Image.open(filename)
        img_data = numpy.array(list(img.getdata()), numpy.uint8)

        texture = glGenTextures(1)
        glPixelStorei(GL_UNPACK_ALIGNMENT,1)
        glBindTexture(GL_TEXTURE_2D, texture)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img.size[0], img.size[1], 0, GL_RGB, GL_UNSIGNED_BYTE, img_data)
        return texture

    def run(self):
        glutInitDisplayMode(GLUT_RGBA)

        glutInitWindowSize(256,224)
        self.window = glutCreateWindow("GL")
        glutDisplayFunc(self.draw)

        glClearColor(0,0,0,0)
        glEnable(GL_TEXTURE_2D)
        glEnable(GL_VERTEX_ARRAY)

        self.MainTex = glGenTextures(1)
        self.SplashTex = self.TexFromPNG("Resources/Splash.png")

        glutMainLoop()

    def draw(self):
        glClear(GL_COLOR_BUFFER_BIT)
        glLoadIdentity()
        if self.Splash:
            glBindTexture(GL_TEXTURE_2D, self.SplashTex)
        else:
            glBindTexture(GL_TEXTURE_2D, self.MainTex)

        glTexParameter(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
        glTexParameter(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER)
        Varray = numpy.array([[0,0],[0,256],[224,256],[224,0]],numpy.uint16)
        glVertexPointer(2,GL_SHORT,0,Varray)
        indices = [0,1,2,3]
        glDrawElements(GL_QUADS,1,GL_UNSIGNED_SHORT,indices)

        glFlush()
thing = ClassThing()
thing.run()

正如我所说，这让我遇到了全黑的屏幕。感觉我可能缺少某种初始化或启用，但我不知道还需要启用什么。

顺便说一句，显然 glVertexPointer 已被弃用，如果没有它，我将如何运行 glDrawElements ？是否可以进行某种类似于纹理生成的顶点生成或其他操作？

Answer 1

难道是因为你调用了glGenTextures(1)两次？您将其分配给 TexFromPNG 中的纹理，并在运行中将其分配给 self.MainTex。

Answer 2

您还需要提供纹理坐标，否则 OpenGL 不知道如何将纹理映射到您的四边形 - 您也可以使用自动纹理坐标生成，但在您的情况下，仅指定坐标更简单。此外还需要指定视口和投影

class ClassThing:
    def __init__(self):
        self.Splash = True

    def TexFromPNG(self, filename):
        img = Image.open(filename)
        img_data = numpy.array(list(img.getdata()), numpy.uint8)

        texture = glGenTextures(1)
        glPixelStorei(GL_UNPACK_ALIGNMENT,1)
        glBindTexture(GL_TEXTURE_2D, texture)

        # Texture parameters are part of the texture object, so you need to 
        # specify them only once for a given texture object.
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR)
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img.size[0], img.size[1], 0, GL_RGB, GL_UNSIGNED_BYTE, img_data)
        return texture

    def run(self):
        glutInitDisplayMode(GLUT_RGBA)

        glutInitWindowSize(256,224)
        self.window = glutCreateWindow("GL")
        glutReshapeFunc(self.reshape)
        glutDisplayFunc(self.draw)

        self.MainTex = glGenTextures(1)
        self.SplashTex = self.TexFromPNG("Resources/Splash.png")

        glutMainLoop()

    def reshape(self, width, height):
        self.width = width
        self.height = height
        glutPostRedisplay();

    def draw(self):
        glViewport(0, 0, self.width, self.height)

        glClearDepth(1) # just for completeness
        glClearColor(0,0,0,0)
        glClear(GL_COLOR_BUFFER_BIT)

        glMatrixMode(GL_PROJECTION)
        glLoadIdentity()
        glOrtho(0, 1, 0, 1, -1, 1)

        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity()

        if self.Splash:
            glBindTexture(GL_TEXTURE_2D, self.SplashTex)
        else:
            glBindTexture(GL_TEXTURE_2D, self.MainTex)

        # it's a good idea to enable state right before you need it
        # there's no such thing like global state intialization in
        # OpenGL
        glEnable(GL_TEXTURE_2D)
        # vertex arrays must be enabled using glEnableClientState
        glEnableClientState(GL_VERTEX_ARRAY)
        glEnableClientState(GL_TEXTURE_COORD_ARRAY)

        Varray = numpy.array([[0,0],[0,1],[1,1],[1,0]],numpy.float)
        glVertexPointer(2,GL_FLOAT,0,Varray)
        glTexCoordPointer(2,GL_FLOAT,0,Varray)
        indices = [0,1,2,3]
        glDrawElements(GL_QUADS,1,GL_UNSIGNED_SHORT,indices)

        # This implies a glFinish, which includes a glFlush
        glutSwapBuffers() 

# GLUT initialization in program global, so initialize it on
# the process level. It might be 
glutInit(sys.argv)

thing = ClassThing()
thing.run()