1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
|
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <math.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL2_gfxPrimitives.h>
#define FRAME_DELAY 5
#define WINDOW_WIDTH 900
#define WINDOW_HEIGHT 600
#define CIRCLE_RAD 100
#define CIRCLE_DIAMETER (CIRCLE_RAD * 2)
#define HISTORY_SIZE (WINDOW_WIDTH - CIRCLE_DIAMETER)
#define POINT_RAD 3
#define PADDING_SIZE 100
#define SEP_SIZE (PADDING_SIZE + 100)
#define HISTORY_COLOR 0xffffffff
#define POINT_COLOR 0xffffffff
#define CIRCLE_COLOR 0xffffffff
int g_history[HISTORY_SIZE] = {0};
double g_angle = 0.0;
int g_circle_count = 1;
bool g_pause = false;
bool g_running = true;
void reset_history(void)
{
for (size_t i = 0; i < HISTORY_SIZE; i++)
g_history[i] = WINDOW_HEIGHT;
}
int main(void)
{
reset_history();
if (SDL_Init(SDL_INIT_VIDEO) != 0)
exit(1);
SDL_Window *window = SDL_CreateWindow(
"fourier-series-viz",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
WINDOW_WIDTH,
WINDOW_HEIGHT,
0
);
if (window == NULL)
exit(1);
SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, 0);
if (renderer == NULL)
exit(1);
while (g_running)
{
SDL_Event e;
while (SDL_PollEvent(&e))
{
switch (e.type)
{
case SDL_QUIT:
g_running = false;
break;
case SDL_KEYDOWN:
switch (e.key.keysym.sym)
{
case SDLK_q:
case SDLK_ESCAPE:
g_running = false;
break;
case SDLK_p:
case SDLK_SPACE:
g_pause = !g_pause;
break;
case SDLK_j:
case SDLK_MINUS:
g_circle_count--;
if (g_circle_count < 1)
g_circle_count = 1;
reset_history();
break;
case SDLK_k:
case SDLK_EQUALS:
g_circle_count++;
reset_history();
break;
}
}
}
if (g_pause)
{
SDL_Delay(FRAME_DELAY);
continue;
}
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
SDL_RenderClear(renderer);
SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
/*
** n = range(1, inf, 2)
**
** 4 * sin(n * theta)
** -----------------
** pi
**
*/
double sum_x = 0.0;
double sum_y = 0.0;
for (int circle_num = 0; circle_num < g_circle_count; circle_num++)
{
double factor = 1 + circle_num * 2;
double radius = (CIRCLE_RAD - 25) * 4 / (factor * M_PI);
double x = radius * cos(factor * g_angle);
double y = radius * sin(factor * g_angle);
int center_x = CIRCLE_RAD + sum_x + PADDING_SIZE;
int center_y = WINDOW_HEIGHT / 2 + sum_y;
aacircleColor(renderer, center_x, center_y, radius, CIRCLE_COLOR);
filledCircleColor(renderer, center_x + x, center_y + y, POINT_RAD, POINT_COLOR);
sum_x += x;
sum_y += y;
}
g_angle += 0.01;
int draw_point_x = CIRCLE_DIAMETER + SEP_SIZE;
int draw_point_y = WINDOW_HEIGHT / 2 + sum_y;
hlineColor(renderer, CIRCLE_RAD + sum_x + PADDING_SIZE, draw_point_x, draw_point_y, HISTORY_COLOR);
filledCircleColor(renderer, draw_point_x, draw_point_y, POINT_RAD, POINT_COLOR);
memmove(g_history + 1, g_history, sizeof(g_history[0]) * (HISTORY_SIZE - 1));
g_history[0] = sum_y;
for (size_t i = 0; i < HISTORY_SIZE - 1; i++)
{
size_t next = i + 1;
if (g_history[next] == WINDOW_HEIGHT)
break;
aalineColor(
renderer,
CIRCLE_DIAMETER + i + SEP_SIZE,
WINDOW_HEIGHT / 2 + g_history[i],
CIRCLE_DIAMETER + next + SEP_SIZE,
WINDOW_HEIGHT / 2 + g_history[next],
HISTORY_COLOR
);
}
SDL_RenderPresent(renderer);
SDL_Delay(FRAME_DELAY);
}
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
|
