avr/animation/animation.c

#include "animation.h"
#include <stdio.h>

int bound(int value, uint8_t min, uint8_t max) {
    if (value > max) {
        return max;
    } else if (value < min) {
        return min;
    } else {
        return value;
    }
}


time_line_t time_line_new(int t0, int y0, int t1, int y1) {
    int dt = t1 - t0;
    int dy = y1 - y0;
    int de = 2 * dy;

    int inc = dy > 0 ? 1 : dy == 0 ? 0 : -1;
    int error;
    
    if (de > 0) {
        error = de - dt;
    } else {
        error = de + dt;
    }

    return (time_line_t){ .y = y0, .dt = dt, .de = de, .error = error, .inc = inc, .dy = dy, .y0 = y0, .y1 = y1 };
}

int time_line_next(time_line_t *self) {
    int error = self->error + self->de;

    if (self->de > 0) {
        while (error >= 0) {
            self->y += self->inc;
            error -= 2 * self->dt;
        }
    } else {
        while (error < 0) {
            self->y += self->inc;
            error += 2 * self->dt;
        }
    }

    if (self->y0 < self->y1) {
        self->y = bound(self->y, self->y0, self->y1);
    } else {
        self->y = bound(self->y, self->y1, self->y0);
    }

    self->error = error;
    return self->y;
}

/*
time_line_t time_line_new(int t0, int y0, int t1, int y1) {
    int dt = t1 - t0;
    int dy = y1 - y0;
    int inc = dy > 0 ? 1 : dy == 0 ? 0 : -1;
    int m = 2 * dy;
    int error = 0;

    if (m > 0) {
        error = m - dt;
    } else {
        error = m + dt;
    }

    return (time_line_t){ .y = y0, .m = m, .error = error, .inc = inc, .dt = dt };
}
*/

/*
int time_line_next(time_line_t *slope) {
    slope->error += slope->m;

    if (slope->m > 0) {
        if (slope->error >= 0) {
            slope->y += slope->inc;
            slope->error -= 2 * slope->dt;
        }
    } else {
        if (slope->error <= 0) {
            slope->y += slope->inc;
            slope->error += 2 * slope->dt;
        }
    }

    return slope->y;
}
*/

void time_line_print(time_line_t *self) {
    printf("y: %d\tde: %d\terror: %d\tinc: %d\t:dt: %d\n", self->y, self->de, self->error, self->inc, self->dt);
}