Skip to main content
Engineering LibreTexts

9.36: Checking if Outside the Active Area

  • Page ID
    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    def isOutsideActiveArea(camerax, cameray, obj):
        # Return False if camerax and cameray are more than
        # a half-window length beyond the edge of the window.
        boundsLeftEdge = camerax - WINWIDTH
        boundsTopEdge = cameray - WINHEIGHT
        boundsRect = pygame.Rect(boundsLeftEdge, boundsTopEdge, WINWIDTH * 3, WINHEIGHT * 3)
        objRect = pygame.Rect(obj['x'], obj['y'], obj['width'], obj['height'])
        return not boundsRect.colliderect(objRect)
    if __name__ == '__main__':

    The isOutsideActiveArea() will return True if the object you pass it is outside of the "active area" that is dictated by the camerax and cameray parameters. Remember that the active area is an area around the camera view the size of the camera view (which has a width and height set by WINWIDTH and WINHEIGHT), like this:

    Figure 53

    We can create a Rect object that represents the active area by passing camerax - WINWIDTH for the left edge value and cameray - WINHEIGHT for the top edge value, and then WINWIDTH * 3 and WINHEIGHT * 3 for the width and height. Once we have the active area represented as a Rect object, we can use the colliderect() method to determine if the object in the obj parameter is collides with (that is, is inside of) the active area Rect object.

    Since the player squirrel, enemy squirrel and grass objects all have 'x', 'y', 'width' and 'height' keys, the isOutsideActiveArea() code can work with any type of those game objects.

    Finally, after all the functions have been defined, the program will run the main() function and start the game.

    This page titled 9.36: Checking if Outside the Active Area is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by Al Sweigart via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

    • Was this article helpful?