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Mend Trochoid math

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h/t Pere for pointing out my mistake!
This commit is contained in:
Bill Kendrick 2024-01-15 22:14:33 -08:00
parent 9ab7b2b3b7
commit ab4cd4fdde
2 changed files with 55 additions and 19 deletions
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71
magic/src/trochoids.c
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@ -5,8 +5,9 @@
Spirograph and Wondergraph.
by Bill Kendrick <bill@newbreedsoftware.com>
with help from Pere Pujal Carabantes
January 6, 2024 - January 7, 2024
January 6, 2024 - January 15, 2024
*/
#include <stdio.h>
@ -17,8 +18,8 @@
#include "SDL_image.h"
#include "SDL_mixer.h"
#define deg_cos(x) cos((float) (x) * M_PI / 180.0)
#define deg_sin(x) sin((float) (x) * M_PI / 180.0)
#define deg_cos(x) cosf((float) (x) * M_PI / 180.0)
#define deg_sin(x) sinf((float) (x) * M_PI / 180.0)
/* All _possible_ tools */
enum
@ -347,17 +348,17 @@ void trochoids_work(magic_api * api, int which,
r = (r / 10) * 10;
/* Epitrochoid: rotator is outside the stator;
Hypotrochoid: rotator is inside the stator */
if (which == TOOL_HYPOTROCHOID_SIZES ||
which == TOOL_HYPOTROCHOID_NOSIZES_1 ||
which == TOOL_HYPOTROCHOID_NOSIZES_2 ||
which == TOOL_HYPOTROCHOID_NOSIZES_3) {
r = -r - 2;
/* Hypotrochoid */
r_ratio = (float) (R - r) / (float) r;
} else {
/* Epitrochoid */
r_ratio = (float) (R + r) / (float) r;
}
r_ratio = (float) (R + r) / (float) r;
/* Size option (or use of alternate tools, if --nomagicsizes)
determines the distance from the center of the rotator
that the pen draws */
@ -378,16 +379,30 @@ void trochoids_work(magic_api * api, int which,
SDL_BlitSurface(snapshot, update_rect, canvas, update_rect);
/* Draw the lines */
LCM = calc_lcm(r, R);
for (a = 0; a < 360.0 * (float) (LCM / R); a++) {
float a2 = (a + 1);
px = trochoids_x + (((R + r) * deg_cos(a)) + (d * deg_cos(r_ratio * a)));
py = trochoids_y + (((R + r) * deg_sin(a)) - (d * deg_sin(r_ratio * a)));
px2 = trochoids_x + (((R + r) * deg_cos((a2))) + (d * deg_cos(r_ratio * a2)));
py2 = trochoids_y + (((R + r) * deg_sin((a2))) - (d * deg_sin(r_ratio * a2)));
api->line((void *)api, which, canvas, snapshot, px, py, px2, py2, (20 * guides) + 1, trochoids_line_callback);
if (which == TOOL_HYPOTROCHOID_SIZES ||
which == TOOL_HYPOTROCHOID_NOSIZES_1 ||
which == TOOL_HYPOTROCHOID_NOSIZES_2 ||
which == TOOL_HYPOTROCHOID_NOSIZES_3) {
/* Hypotrochoid */
px = trochoids_x + (((R - r) * deg_cos(a)) + (d * deg_cos(r_ratio * a)));
py = trochoids_y + (((R - r) * deg_sin(a)) - (d * deg_sin(r_ratio * a)));
px2 = trochoids_x + (((R - r) * deg_cos((a2))) + (d * deg_cos(r_ratio * a2)));
py2 = trochoids_y + (((R - r) * deg_sin((a2))) - (d * deg_sin(r_ratio * a2)));
} else {
/* Epitrochoid */
px = trochoids_x + (((R + r) * deg_cos(a)) - (d * deg_cos(r_ratio * a)));
py = trochoids_y + (((R + r) * deg_sin(a)) - (d * deg_sin(r_ratio * a)));
px2 = trochoids_x + (((R + r) * deg_cos((a2))) - (d * deg_cos(r_ratio * a2)));
py2 = trochoids_y + (((R + r) * deg_sin((a2))) - (d * deg_sin(r_ratio * a2)));
}
api->line((void *)api, which, canvas, snapshot, px, py, px2, py2, (20 * (guides && (a >= 360.0))) + 1, trochoids_line_callback);
}
if (guides) {
@ -405,16 +420,38 @@ void trochoids_work(magic_api * api, int which,
api->xorpixel(canvas, px + 1, py + 1);
/* Rotator (rolling circle) */
px = (int) ((float) trochoids_x + ((R + r) * deg_cos(rotator_anim_a)) + ((float) r * deg_cos(a)));
py = (int) ((float) trochoids_y + ((R + r) * deg_sin(rotator_anim_a)) - ((float) r * deg_sin(a)));
if (which == TOOL_HYPOTROCHOID_SIZES ||
which == TOOL_HYPOTROCHOID_NOSIZES_1 ||
which == TOOL_HYPOTROCHOID_NOSIZES_2 ||
which == TOOL_HYPOTROCHOID_NOSIZES_3) {
/* Hypotrochoid */
px = (int) ((float) trochoids_x + ((R - r) * deg_cos(rotator_anim_a)) + ((float) -r * deg_cos(a)));
py = (int) ((float) trochoids_y + ((R - r) * deg_sin(rotator_anim_a)) - ((float) -r * deg_sin(a)));
} else {
/* Epitrochoid */
px = (int) ((float) trochoids_x + ((R + r) * deg_cos(rotator_anim_a)) + ((float) r * deg_cos(a)));
py = (int) ((float) trochoids_y + ((R + r) * deg_sin(rotator_anim_a)) - ((float) r * deg_sin(a)));
}
api->xorpixel(canvas, px, py);
api->xorpixel(canvas, px + 1, py);
api->xorpixel(canvas, px, py + 1);
api->xorpixel(canvas, px + 1, py + 1);
}
px = (int) ((float) trochoids_x + ((R + r) * deg_cos(rotator_anim_a)) + ((float) d * deg_cos(0)));
py = (int) ((float) trochoids_y + ((R + r) * deg_sin(rotator_anim_a)) - ((float) d * deg_sin(0)));
/* Pen */
if (which == TOOL_HYPOTROCHOID_SIZES ||
which == TOOL_HYPOTROCHOID_NOSIZES_1 ||
which == TOOL_HYPOTROCHOID_NOSIZES_2 ||
which == TOOL_HYPOTROCHOID_NOSIZES_3) {
/* Hypotrochoid */
px = trochoids_x + (((R - r) * deg_cos(rotator_anim_a)) + (d * deg_cos(rotator_anim_a)));
py = trochoids_y + (((R - r) * deg_sin(rotator_anim_a)) - (d * deg_sin(rotator_anim_a)));
} else {
/* Epitrochoid */
px = trochoids_x + (((R + r) * deg_cos(rotator_anim_a)) - (d * deg_cos(rotator_anim_a)));
py = trochoids_y + (((R + r) * deg_sin(rotator_anim_a)) - (d * deg_sin(rotator_anim_a)));
}
for (int yy = -2; yy <= 2; yy++) {
for (int xx = -2; xx <= 2; xx++) {
api->putpixel(canvas, px + xx, py + yy, trochoids_color);