In this recipe we will take the position coordinates of the previous tutorial and make a graph from them. Perform the following steps to do so:
use
function. This function has to be called immediately after importing the main Matplotlib module and before other Matplotlib modules are imported.import matplotlib as mpl mpl.use("Agg")
import matplotlib.pyplot as plt import matplotlib.backends.backend_agg as agg fig = plt.figure(figsize=[3, 3]) ax = fig.add_subplot(111) canvas = agg.FigureCanvasAgg(fig)
def plot(data): ax.plot(data) canvas.draw() renderer = canvas.get_renderer() raw_data = renderer.tostring_rgb() size = canvas.get_width_height() return pygame.image.fromstring(raw_data, size, "RGB")
The following screenshot shows the animation in action. You can also view a screencast on YouTube at https://www.youtube.com/watch?v=t6qTeXxtnl4.
import pygame, sys from pygame.locals import * import numpy as np import matplotlib as mpl mpl.use("Agg") import matplotlib.pyplot as plt import matplotlib.backends.backend_agg as agg fig = plt.figure(figsize=[3, 3]) ax = fig.add_subplot(111) canvas = agg.FigureCanvasAgg(fig) def plot(data): ax.plot(data) canvas.draw() renderer = canvas.get_renderer() raw_data = renderer.tostring_rgb() size = canvas.get_width_height() return pygame.image.fromstring(raw_data, size, "RGB") pygame.init() clock = pygame.time.Clock() screen = pygame.display.set_mode((400, 400)) pygame.display.set_caption('Animating Objects') img = pygame.image.load('head.jpg') steps = np.linspace(20, 360, 40).astype(int) right = np.zeros((2, len(steps))) down = np.zeros((2, len(steps))) left = np.zeros((2, len(steps))) up = np.zeros((2, len(steps))) right[0] = steps right[1] = 20 down[0] = 360 down[1] = steps left[0] = steps[::-1] left[1] = 360 up[0] = 20 up[1] = steps[::-1] pos = np.concatenate((right.T, down.T, left.T, up.T)) i = 0 history = np.array([]) surf = plot(history) while True: # Erase screen screen.fill((255, 255, 255)) if i >= len(pos): i = 0 surf = plot(history) screen.blit(img, pos[i]) history = np.append(history, pos[i]) screen.blit(surf, (100, 100)) i += 1 for event in pygame.event.get(): if event.type == QUIT: pygame.quit() sys.exit() pygame.display.update() clock.tick(30)
The plotting-related functions are explained in the following table:
Function |
Description |
---|---|
This specifies the use of the noninteractive backend. | |
This creates a figure of 3 x 3 inches. | |
This creates a canvas in noninteractive mode. | |
This draws on the canvas. | |
This gets a renderer for the canvas. |