Forem: Sean Watkins

Making a Christmas Tree

Sean Watkins — Thu, 21 Apr 2022 12:34:25 +0000

Why make a Christmas tree in April? I don't know but it's harder than you might think, if you want a good one at least. To make a good Christmas tree you have to have at least four components the trunk, leaves, pot and baubles.

//Trunk
    colour(150, 75, 10);
    rect(378, 150, 44, 425);

The trunk is simple, a brown coloured rectangle. To make brown with RGB you have to make orange, red plus a little green. Then just reduce the numbers to make brown, which is, to the best of my knowledge, a dark orange.

//Leaves
    for (int y = 500; y >= 100; y = y - 20) {
        int w = y / 2;
        int h = y / 3;
                int green = 250 - y * 200 / 500; 
        colour(0, green, 0);
        tri(400 - w / 2, y, 400 + w / 2, y, 400, y - h);
    }

The Leaves are not as simple, I did some special things to make the trees leaves look like a golden cyprus.

I am making the tree out of triangles. The loop counts backwards from y = 500 to y = 100, 20 pixels at a time. I am starting at 500, which is near the bottom of the 800 × 600 canvas.

I calculate the width w and height h of the triangle based on the y coordinate, so that the triangles get smaller towards the top of the tree.

To make the tree become gradually lighter closer to the top of the canvas, I vary the amount of green based on the y coordinate. The y coordinate ranges from 100 to 500. First divide by 500 to make it approximately between 0 and 1. Then multiply by 200 to put it on the RGB scale from 0 to 255. Subtract from 250 so that the amount of green ranges roughly between 250 for the light green at the top of the tree, and 50 for the dark green at the bottom of the tree.

//Pot
    colour(75, 37, 10);
    quad(360, 530, 440, 530, 425, 590, 375, 590);

    colour(90, 45, 12);
    rect(355, 528, 90, 10);

Now we have a basic pine tree but it doesn't have a place to live... So let's put it in a comically small pot! All we need to do is put a quadrilateral with a smaller base for the body of the pot and a skinny rectangle at the top to be the brim.

//BAUBLES
    srandom(6);
    for (int i = 0; i < 36; i++) {
        if (i % 2) {
            colour(255, 0, 0);
        } else {
            colour(255, 200, 0);
        }
        int x, y;
        int w;
        do {
            y = random() % 433 + 67;
            x = random() % 250 + 275;
            w = y / 2;
        } while (x < 400 - w/2 || x > 400 + w/2);
        circle(x, y, 10);
    }

Finally, we have to show that is isn't just a pine tree, so let's add some baubles. To be honest I didn't program this, my dad did, and I have no idea how this was done. So let's hand over to dad:

We want to draw 36 baubles, so we have a loop to count from i = 0 to 35. The odd numbered ones where i % 2 == 1 are red, and the even numbered ones are gold, but we can't make them shiny, at least not today.

We choose a random point in a rectangle that surrounds the tree, its "bounding box", then work out the width of the tree at that y position. If the point is to the left or right of the tree, it tries again with a new random point using a do ... while loop.

Finally, we draw a small circle of radius 10 pixels at the chosen point.

The srandom(6) call at the top of this section seeds the random number generator. Seeding with a constant value like this gives us the same pattern of baubles each time we run the program. Number 6 happened to give a fairly good looking pattern.

Here is the full code to draw the Christmas tree.

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Previous post: Creating Drawings, by Thalia
Contents: Game Dev From Scratch

Loops and Math in C

Sean Watkins — Thu, 14 Apr 2022 09:16:55 +0000

I have over the last couple days, been learning more about the basics of C the programming language! Let me recap what I've learned for you.

I have already, similar to my sister (thalia), learned the very basics such as how to use the standard input/output library #include <stdio.h> and printf("Hello, world");.

To see more about this, please read Thalia's post.

loops.c

#include <stdio.h>

int main(void)
{
    for (int i = 0; i < 100; i++) {
        printf("Hello, Jerome. ");
    }

    int i = 0;

    while (i <= 1000) {
        printf("%d ", i);
        i = i + 1;
    }

    return 0;
}

I wrote a for loop to print a message 100 times, and a while loop to print the numbers from 0 to 1000 using the %d format to print integers in decimal.

In the for loop, all of the loop control is in one place, whereas in the while loop the initializer, test and increment are scattered around the code.

maths.c

#include <stdio.h>
#include <string.h>

int main(void)
{
    char *star_name = "Proxima Centauri";
    double star_distance_ly = 4.2465;
    double c = 299792458;
    double seconds_in_year = 3600 * 24 * 365.2422;
    double light_year = c * seconds_in_year;
    double star_distance_km = star_distance_ly * light_year / 1000;

    printf("The distance to %s is %.0f km.\n", star_name, star_distance_km);

    return 0;
}

This is probably already apparent, but maths is an extremely important part of any programming language, especially if you want to make games. This is why I thought a good next step would be to see if I could make simple calculations through C. I have, again, been watching more Kurzgesagt videos on YT. Inevitably I found many great videos on their channel about space and our universe, this got me wondering about the closest stars to our own.

This little program converts the distance to the closet star from light-years to kilometres. I used double variables; these are double-precision floating point numbers. We can print a double with %f and rounded off to a whole number with %.0f for 0 decimal places.

Next post: Basic Programming in C, by Sam
Previous post: My Simple Programs, by Thalia
Contents: Game Dev From Scratch

Creating Games

Sean Watkins — Tue, 05 Apr 2022 10:47:58 +0000

Recently, I have found myself wanting more and more to be able to play this game my imagination conjured up, a fast-paced multiplayer strategy game, in which you would be in charge of an entire ant colony, fighting against other ant colonies, gathering resources and becoming the strongest ant colony ever.

The only problem is that unsurprisingly, I couldn't find a game that was similar enough to the one I imagined that could satisfy my peculiar desire to command an army of ants and crush other inferior colonies! This is why, together with my sister and father, I have decided to learn how to create video games.

We are starting by learning how to program in C. Then we intend to develop our skills by making some simple games, and work towards the goal of creating an online multiplayer game based on the ant colony idea. We are writing about our progress here on this blog.

I first got the inspiration for this idea when I was watching a YouTube video made by Kurzgesagt (see below) explaining the life and daily struggle of weaver ants. The weaver ants create cities in the sky, with many castles high in the tree canopy, and bridges connecting to outposts at their borders.

I found it extremely interesting because although each individual is almost mindless, together these incredible ants work as one to accomplish amazing things. The ant colony reminds me of the second most complex system in our bodies, the immune system, where many mindless cells cooperate to defend the body.

Please follow along if you like the idea or are also interested in making games. Thanks for reading!

Next post: Deciding on a Programming Language for Game Dev, by Sam
Contents: Game Dev From Scratch