summaryrefslogtreecommitdiff
path: root/src/modules/meta2d/meta2d.c
blob: ddf20f16273cd82dee7cb10890448c8ec86d0d8a (plain)
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
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
/*
 *  Copyright (C) 2019 - Vito Caputo - <vcaputo@pengaru.com>
 *
 *  This program is free software: you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License version 2 as published
 *  by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/* https://en.wikipedia.org/wiki/Metaballs */

#include <stdlib.h>
#include <unistd.h>

#include "til.h"
#include "til_fb.h"

#include "din/din.h"

#include "v2f.h"
#include "v3f.h"

#define	META2D_NUM_BALLS	10

typedef struct meta2d_ball_t {
	v2f_t		position;
	float		radius;
	v3f_t		color;
} meta2d_ball_t;

typedef struct meta2d_context_t {
	unsigned	n;
	din_t		*din_a, *din_b;
	float		din_t;
	unsigned	n_cpus;
	meta2d_ball_t	balls[META2D_NUM_BALLS];
} meta2d_context_t;


/* convert a color into a packed, 32-bit rgb pixel value (taken from libs/ray/ray_color.h) */
static inline uint32_t color_to_uint32(v3f_t color) {
	uint32_t	pixel;

	if (color.x > 1.0f) color.x = 1.0f;
	if (color.y > 1.0f) color.y = 1.0f;
	if (color.z > 1.0f) color.z = 1.0f;

	if (color.x < .0f) color.x = .0f;
	if (color.y < .0f) color.y = .0f;
	if (color.z < .0f) color.z = .0f;

	pixel = (uint32_t)(color.x * 255.0f);
	pixel <<= 8;
	pixel |= (uint32_t)(color.y * 255.0f);
	pixel <<= 8;
	pixel |= (uint32_t)(color.z * 255.0f);

	return pixel;
}


static void * meta2d_create_context(unsigned ticks, unsigned num_cpus, void *setup)
{
	meta2d_context_t	*ctxt;

	ctxt = calloc(1, sizeof(meta2d_context_t));

	/* perlin noise is used for some organic-ish random movement of the balls */
	ctxt->din_a = din_new(10, 10, META2D_NUM_BALLS + 2);
	ctxt->din_b = din_new(10, 10, META2D_NUM_BALLS + 2);

	srand(getpid());
	ctxt->n_cpus = num_cpus;

	for (int i = 0; i < META2D_NUM_BALLS; i++) {
		meta2d_ball_t	*ball = &ctxt->balls[i];

		v2f_rand(&ball->position, &(v2f_t){-.7f, -.7f}, &(v2f_t){.7f, .7f});
		ball->radius = rand() / (float)RAND_MAX * .2f + .05f;
		v3f_rand(&ball->color, &(v3f_t){0.f, 0.f, 0.f}, &(v3f_t){1.f, 1.f, 1.f});
	}

	return ctxt;
}


static void meta2d_destroy_context(void *context)
{
	meta2d_context_t	*ctxt = context;

	din_free(ctxt->din_a);
	din_free(ctxt->din_b);
	free(ctxt);
}


static int meta2d_fragmenter(void *context, const til_fb_fragment_t *fragment, unsigned number, til_fb_fragment_t *res_fragment)
{
	meta2d_context_t	*ctxt = context;

	return til_fb_fragment_slice_single(fragment, ctxt->n_cpus, number, res_fragment);
}


static void meta2d_prepare_frame(void *context, unsigned ticks, unsigned n_cpus, til_fb_fragment_t *fragment, til_fragmenter_t *res_fragmenter)
{
	meta2d_context_t	*ctxt = context;

	*res_fragmenter = meta2d_fragmenter;

	/* move the balls around */
	for (int i = 0; i < META2D_NUM_BALLS; i++) {
		meta2d_ball_t	*ball = &ctxt->balls[i];
		float		rad;

		/* Perlin noise indexed by position for x,y and i for z
		 * is used just for moving the metaballs around.
		 *
		 * Two noise fields are used with their values interpolated,
		 * starting with the din_a being 100% of the movement,
		 * with every frame migrating closer to din_b being 100%.
		 *
		 * Once din_b contributes 100%, it becomes din_a, and the old
		 * din_a becomes din_b which gets randomized, and the % resets
		 * to 0.
		 *
		 * This allows an organic continuous evolution of the field
		 * over time, at double the sampling cost since we're sampling
		 * two noise fields and interpolating them.  Since this is
		 * just per-ball every frame, it's probably OK.  Not like it's
		 * every pixel.
		 */

		/* ad-hoc lerp of the two dins */
		rad = din(ctxt->din_a, &(v3f_t){
			  .x = ball->position.x,
			  .y = ball->position.y,
			  .z = (float)i * (1.f / (float)META2D_NUM_BALLS)}
			 ) * (1.f - ctxt->din_t);

		rad += din(ctxt->din_b, &(v3f_t){
			  .x = ball->position.x,
			  .y = ball->position.y,
			  .z = (float)i * (1.f / (float)META2D_NUM_BALLS)}
			 ) * ctxt->din_t;

		/* Perlin noise doesn't produce anything close to a uniform random distribution
		 * of -1..+1, so it can't just be mapped directly to 2*PI with all angles getting
		 * roughly equal occurrences in the long-run.  For now I just *10.f and it seems
		 * to be OK.
		 */
		rad *= 10.f * 2.f * M_PI;
		v2f_add(&ball->position,
			&ball->position,
			&(v2f_t){
				.x = cosf(rad) * .003f,	/* small steps */
				.y = sinf(rad) * .003f,
			});

		v2f_clamp(&ball->position,
			  &ball->position,
			  &(v2f_t){-.8f, -.8f},	/* keep the balls mostly on-screen */
			  &(v2f_t){.8f, .8f}
			);
	}

	/* when din_t reaches 1 swap a<->b, reset din_t, randomize b */
	ctxt->din_t += .01f;
	if (ctxt->din_t >= 1.f) {
		din_t	*tmp;

		tmp = ctxt->din_a;
		ctxt->din_a = ctxt->din_b;
		ctxt->din_b = tmp;

		din_randomize(ctxt->din_b);
		ctxt->din_t = 0.f;
	}
}


static void meta2d_render_fragment(void *context, unsigned ticks, unsigned cpu, til_fb_fragment_t *fragment)
{
	meta2d_context_t	*ctxt = context;
	float			xf = 2.f / (float)fragment->frame_width;
	float			yf = 2.f / (float)fragment->frame_height;
	v2f_t			coord;

	for (int y = fragment->y; y < fragment->y + fragment->height; y++) {
		coord.y = yf * (float)y - 1.f;

		for (int x = fragment->x; x < fragment->x + fragment->width; x++) {
			v3f_t		color = {};
			uint32_t	pixel;
			float		t = 0;

			coord.x = xf * (float)x - 1.f;

			for (int i = 0; i < META2D_NUM_BALLS; i++) {
				meta2d_ball_t	*ball = &ctxt->balls[i];

				float	f;

				f = ball->radius * ball->radius / v2f_distance_sq(&coord, &ball->position);
				v3f_add(&color, &color, v3f_mult_scalar(&(v3f_t){}, &ball->color, f));
				t += f;
			}

			/* these thresholds define the thickness of the ribbon */
			if (t < .7f || t > .8f)
				color = (v3f_t){};

			pixel = color_to_uint32(color);
			til_fb_fragment_put_pixel_unchecked(fragment, x, y, pixel);
		}
	}
}


til_module_t	meta2d_module = {
	.create_context = meta2d_create_context,
	.destroy_context = meta2d_destroy_context,
	.prepare_frame = meta2d_prepare_frame,
	.render_fragment = meta2d_render_fragment,
	.name = "meta2d",
	.description = "Classic 2D metaballs (threaded)",
	.author = "Vito Caputo <vcaputo@pengaru.com>",
};
© All Rights Reserved