在 Python 中使用 OpenGL 和 Gtk 进行 3D 绘制时，启用混合后，混合仍然不起作用。
2、解决方案
2.1 问题分析
在混合不起作用的情况下，需要检查几个方面：
- 确保已启用混合。在 OpenGL 中，可以使用 glEnable(GL_BLEND) 启用混合。
- 设置混合函数。可以使用 glBlendFunc() 设置混合函数。
- 确保源图像和目标图像具有透明度信息。源图像和目标图像都需要具有透明度信息，才能进行混合。
- 确保混合模式正确。在 OpenGL 中，可以使用 GL_SRC_ALPHA 和 GL_ONE_MINUS_SRC_ALPHA 等混合模式。
2.2 代码示例
import sys
import OpenGL.GL as GL
import OpenGL.GLU as GLU
import OpenGL.GLUT as GLUT
from OpenGL.raw._GLX import struct__XDisplay
import Xlib
import Xlib.display
from gi.repository import Gtk, GdkX11, Gdk
class gtkgl:
""" these method do not seem to exist in python x11 library lets exploit the c methods """
xlib = cdll.LoadLibrary('libX11.so')
xlib.XOpenDisplay.argtypes = [c_char_p]
xlib.XOpenDisplay.restype = POINTER(struct__XDisplay)
xdisplay = xlib.XOpenDisplay("")
display = Xlib.display.Display()
attrs = []
xwindow_id = None
width = height = 200
def __init__(self):
""" lets setup are opengl settings and create the context for our window """
self.add_attribute(GLX.GLX_RGBA, True)
self.add_attribute(GLX.GLX_RED_SIZE, 1)
self.add_attribute(GLX.GLX_GREEN_SIZE, 1)
self.add_attribute(GLX.GLX_BLUE_SIZE, 1)
self.add_attribute(GLX.GLX_ALPHA_SIZE, 1)
self.add_attribute(GLX.GLX_DOUBLEBUFFER, 0)
glClearDepth(1.0)
glEnable(GL_DEPTH_TEST)
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
glShadeModel(GL_SMOOTH)
glDepthFunc(GL_LEQUAL)
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST)
glEnable(GL_COLOR_MATERIAL)
glEnable(GL_LIGHTING)
glEnable(GL_LIGHT0)
glLight(GL_LIGHT0, GL_POSITION, (0, 1, 1, 0))
xvinfo = GLX.glXChooseVisual(self.xdisplay, self.display.get_default_screen(), self.get_attributes())
configs = GLX.glXChooseFBConfig(self.xdisplay, 0, None, byref(c_int()))
self.context = GLX.glXCreateContext(self.xdisplay, xvinfo, None, True)
def add_attribute(self, setting, value):
"""just to nicely add opengl parameters"""
self.attrs.append(setting)
self.attrs.append(value)
def get_attributes(self):
""" return our parameters in the expected structure"""
attrs = self.attrs + [0, 0]
return (c_int * len(attrs))(*attrs)
def configure(self, wid):
""" """
self.xwindow_id = GdkX11.X11Window.get_xid(wid)
if(not GLX.glXMakeCurrent(self.xdisplay, self.xwindow_id, self.context)):
print 'failed'
glViewport(0, 0, self.width, self.height)
def draw_start(self):
"""make cairo context current for drawing"""
if(not GLX.glXMakeCurrent(self.xdisplay, self.xwindow_id, self.context)):
print "failed"
def draw_finish(self):
"""swap buffer when we have finished drawing"""
GLX.glXSwapBuffers(self.xdisplay, self.xwindow_id)
def test(self):
"""Test method to draw something so we can make sure opengl is working and we can see something"""
self.draw_start()
glClearColor(0.0, 0.0, 0.0, 0.0)
glClear(GL_COLOR_BUFFER_BIT)
glBegin(GL_TRIANGLES)
glIndexi(0)
glColor4f(1.0, 0.0, 0.0, 0.2)
glVertex2i(0, 1)
glIndexi(0)
glColor4f(0.0, 1.0, 0.0, 0.2)
glVertex2i(-1, -1)
glIndexi(0)
glColor4f(0.0, 0.0, 1.0, 1.0)
glVertex2i(1, -1)
glEnd()
self.draw_finish()
class gui():
glwrap = gtkgl()
def __init__(self):
self.window = Gtk.Window()
self.window.realize()
self.window.resize(self.glwrap.width, self.glwrap.height)
self.window.set_resizable(True)
self.window.set_reallocate_redraws(True)
self.window.set_title("GTK3 with opengl")
self.window.connect('delete_event', Gtk.main_quit)
self.window.connect('destroy', lambda quit: Gtk.main_quit())
self.drawing_area = Gtk.DrawingArea()
self.drawing_area.connect('configure_event', self.on_configure_event)
self.drawing_area.connect('draw', self.on_draw)
self.drawing_area.set_double_buffered(False)
self.drawing_area.set_size_request(self.glwrap.width, self.glwrap.height)
self.window.add(self.drawing_area)
self.window.show_all()
def on_configure_event(self, widget, event):
self.glwrap.configure(widget.get_window())
return True
def on_draw(self, widget, context):
self.glwrap.test()
def main():
g = gui()
Gtk.main()
if __name__ == '__main__':
main()
2.3 总结
混合在 OpenGL 中是一个非常重要的概念，它可以用来创建各种各样的视觉效果。在使用 OpenGL 进行 3D 绘制时，混合是必不可少的。希望这篇技术文章能够帮助您解决混合不起作用的问题。
