Line code

lines.c

void drawLine(short x1, short y1, short x2, short y2, char color) {
    short dx = x2 - x1;
    short dy = y2 - y1;
    short newX = x1;
    short newY = y1;
    
    // Iterate along the X axis if slope is not steep (m <= 1)
    if (dx >= dy) {
        for (; newX <= x2; newX++) {
            setPixel(
                newX,
                ((dy * newX) / dx) + y1,
                color);
        }
    }
    
    // Iterate along the Y axis if slope is steep (m > 1)
    else {
        for (; newY <= y2; newY++) {
            setPixel(
                ((dx * newY) / dy) + x1,
                newY,
                color);
        }
    }
}

/*
    When the X axis is the major axis...
    
    y = mx+b;
    
    setPixel(x, mx+b, color);
*/