小精灵OpenGL。如何基于“ z”轴在其他物体前面绘制矩形

时间:2018-10-31 20:51:19

标签: python python-3.x opengl 3d pyglet

环境:

Python:3.6.6
pyglet版本:1.3.2
操作系统(两者均复制):Windows 10主机,Ubuntu 14.04来宾(不带3d加速的Virtualbox)

代码:

code in github

import pyglet


class Window(pyglet.window.Window):

    def __init__(self, *args, **kwargs):
        super(Window, self).__init__(*args, **kwargs)
        self.batch = pyglet.graphics.Batch()
        self.position = [0, 0, 300.0]
        self.vertices_list = []

        # BLUE rect
        self.add_rect("blue.png", x=0, y=0, z=0)
        # RED rect
        self.add_rect("red.png", x=10, y=10, z=10)
        # Expects RED will be in front of BLUE, but it isn't
        # BLUE on top regardless of z value. I tried -10/10, etc.

        pyglet.clock.schedule_interval(self.move_red_forward, 1 / 60)

    def add_rect(self, file_name, x, y, z):
        image = pyglet.image.load(file_name)
        image_grid = pyglet.image.ImageGrid(image, 1, 1)
        texture_grid = image_grid.get_texture_sequence()
        texture_group = pyglet.graphics.TextureGroup(texture_grid)
        x_ = (texture_group.texture.width + x)
        y_ = (texture_group.texture.height + y)
        tex_coords = ('t3f', texture_grid[0].texture.tex_coords)

        vert_list = self.batch.add(
            4, pyglet.gl.GL_QUADS,
            texture_group,
            ('v3f', (x, y, z,
                     x_, y, z,
                     x_, y_, z,
                     x, y_, z)),
            tex_coords)
        self.vertices_list.append(vert_list)

    def move_red_forward(self, dt):
        # move z += 1 for all corners
        red_vertices = self.vertices_list[1].vertices
        red_vertices[2] += 1
        red_vertices[5] += 1
        red_vertices[8] += 1
        red_vertices[11] += 1

    def set_3d(self):
        width, height = self.get_size()
        pyglet.graphics.glEnable(pyglet.graphics.GL_BLEND)
        pyglet.graphics.glBlendFunc(
            pyglet.graphics.GL_SRC_ALPHA,
            pyglet.graphics.GL_ONE_MINUS_SRC_ALPHA)
        pyglet.graphics.glViewport(0, 0, width, height)
        pyglet.graphics.glMatrixMode(pyglet.graphics.GL_PROJECTION)
        pyglet.graphics.glLoadIdentity()
        pyglet.graphics.gluPerspective(90, width / height, 0.1, 6000.0)
        pyglet.graphics.glMatrixMode(pyglet.graphics.GL_MODELVIEW)
        pyglet.graphics.glLoadIdentity()
        x, y, z = self.position
        pyglet.graphics.glTranslatef(x, y, -z)

    def on_draw(self):
        self.clear()
        self.set_3d()
        self.batch.draw()


if __name__ == '__main__':
    window = Window(width=1400, height=800, caption='Pyglet', resizable=True)
    pyglet.app.run()

问题:

part of screenshot
蓝色矩形在红色前面绘制。我希望z轴负责定义应该在前面绘制的对象。

问题:

我该如何实现?
还是在了解这种过程时错过了什么?

1 个答案:

答案 0 :(得分:2)

您必须启用Depth Test

pyglet.graphics.glEnable(pyglet.graphics.GL_DEPTH_TEST)

请注意,默认深度功能为GL_LESS,如果片段在同一位置绘制,并且新片段的深度大于或等于深度,则这会导致片段被丢弃的片段。

如果未启用深度测试,则以后的几何图形总是绘制在前者的顶部。


如果要将红色图像混合在蓝色图像上,则必须禁用深度测试,并且必须在蓝色图像之后绘制红色图像。对于Blending,绘制顺序至关重要。后一个对象通过混合函数(glBlendFunc)和混合方程式(glBlendEquation)与前一个对象混合。
更改图像的顺序:

 self.add_rect("red.png", x=10, y=10, z=10) 
 self.add_rect("blue.png", x=0, y=0, z=0)