We have some hard work coming in the next few episodes. Before we get there, let's get a couple incidentals out of the way. Reclaiming space Recall in the last few episodes we shrank our scene by 32 pixels vertically to give us room for text interaction at
We're going to take a little bit of a break from graphics and work on adding one of the defining features of the original King's Quest – a text interface underneath the scene. In King's Quest 1, you move Sir Grahame around and navigate between
One of the cool things about the original King's Quest was how they added a sense of depth to a two-dimensional scene. Just check it out: Sir Grahame emerges from behind the tree and walks around behind the well. And just a few seconds later, he is inside
In Episode 14 we wrote a Python script to take any 320x200 16-color PNG image and convert it to a format that can be used in our app, then we added code to load and display the image as our background. But our character just walks all over the image,
In Episode 12 we achieved fast, flicker-free character movement over a solid-color background via double-buffering. In Episode 13 we added a third video buffer, allowing us to have any arbitrary background. We demonstrated that by drawing a solid blue background with two rectangles over it. In this lesson we will
In Episode 12 we moved to a double-buffering scheme where the CPU draws the scene in a separate buffer, taking as long as it needs, then copies the finished product to video memory for display. It works great, except... our background is kinda bland: We draw the background using a
We thought we had fixed the flickering in Episode 10 when we made our draw_rect subroutine more efficient, but if you notice in the Episode 11 DOSBox video (and even more prominently in the video of the code running on my actual PCjr), it still appears occasionally. Our icon
Last episode saw us greatly increase the speed of our rectangle-rendering function by taking the rectangle line-by-line instead of pixel-by-pixel. In this episode we're going to adapt our function to drawing icons with just a couple extra lines of code. First we need an icon! The 320x200 CGI-Plus
When I last blogged on this project, over a year ago, I had all but given up. I was stuck on the fact that even after hours of optimization, my method of drawing an 8x8 block of pixels (by plotting each pixel individually) was just too slow for a workable
Let me go ahead and apologize for this episode. You know how some days you code for 5 minutes and it makes a huge improvement in your app... and some days you debug for 8 hours and the only "progress" you can say you've made is
First things first, we left the code in a sorry state at the end of the last episode. Let's do some organizing. We have some code that's specific to our program, such as the process_key and draw_player procedures. We also have some generic code
Last time, we figured out how to draw single pixels on the screen. Armed with this knowledge, we should be able to fill the whole screen with a background color and draw a little figure representing the player. In place of our setpixel calls, here's nice little double