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libobs/graphics/math-extra.c

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+/******************************************************************************
+    Copyright (C) 2013 by Hugh Bailey <obs.jim@gmail.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    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/>.
+******************************************************************************/
+
+#include <stdlib.h>
+#include "vec2.h"
+#include "vec3.h"
+#include "math-extra.h"
+
+void polar_to_cart(struct vec3 *dst, const struct vec3 *v)
+{
+	struct vec3 cart;
+	float  sinx = cosf(v->x);
+	float  sinx_z = v->z * sinx;
+
+	cart.x = sinx_z * sinf(v->y);
+	cart.z = sinx_z * cosf(v->y);
+	cart.y = v->z   * sinf(v->x);
+
+	vec3_copy(dst, &cart);
+}
+
+void cart_to_polar(struct vec3 *dst, const struct vec3 *v)
+{
+	struct vec3 polar;
+	polar.z = vec3_len(v);
+
+	if (close_float(polar.z, 0.0f, EPSILON)) {
+		vec3_zero(&polar);
+	} else {
+		polar.x = asinf(v->y / polar.z);
+		polar.y = atan2f(v->x, v->z);
+	}
+
+	vec3_copy(dst, &polar);
+}
+
+void norm_to_polar(struct vec2 *dst, const struct vec3 *norm)
+{
+	dst->x = atan2f(norm->x, norm->z);
+	dst->y = asinf(norm->y);
+}
+
+void polar_to_norm(struct vec3 *dst, const struct vec2 *polar)
+{
+	float sinx = sinf(polar->x);
+
+	dst->x = sinx * cosf(polar->y);
+	dst->y = sinx * sinf(polar->y);
+	dst->z = cosf(polar->x);
+}
+
+float calc_torquef(float val1, float val2, float torque, float min_adjust,
+		float t)
+{
+	float out = val1;
+	float dist;
+	bool  over;
+
+	if (val1 == val2)
+		return val1;
+
+	dist = (val2-val1)*torque;
+	over = dist > 0.0f;
+
+	if (over) {
+		if (dist < min_adjust) /* prevents from going too slow */
+			dist = min_adjust;
+		out += dist*t;         /* add torque */
+		if (out > val2)        /* clamp if overshoot */
+			out = val2;
+	} else {
+		if (dist > -min_adjust)
+			dist = -min_adjust;
+		out += dist*t;
+		if (out < val2)
+			out = val2;
+	}
+
+	return out;
+}
+
+void calc_torque(struct vec3 *dst, const struct vec3 *v1,
+		const struct vec3 *v2, float torque, float min_adjust,
+		float t)
+{
+	struct vec3 line, dir;
+	float orig_dist, torque_dist, adjust_dist;
+
+	if (vec3_close(v1, v2, EPSILON)) {
+		vec3_copy(dst, v1);
+		return;
+	}
+
+	vec3_sub(&line, v2, v1);
+	orig_dist = vec3_len(&line);
+	vec3_mulf(&dir, &line, 1.0f/orig_dist);
+
+	torque_dist = orig_dist*torque; /* use distance to determine speed */
+	adjust_dist = torque_dist*t;
+
+	if (torque_dist < min_adjust)   /* prevent from going too slow */
+		torque_dist = min_adjust;
+
+	if (adjust_dist <= (orig_dist-LARGE_EPSILON)) {
+		vec3_mulf(dst, &dir, adjust_dist);
+		vec3_add(dst, dst, v1); /* add torque */
+	} else {
+		vec3_copy(dst, v2);     /* clamp if overshoot */ 
+	}
+}
+
+float rand_float(int positive_only)
+{
+	if (positive_only)
+		return (float)((double)rand()/(double)RAND_MAX);
+	else
+		return (float)(((double)rand()/(double)RAND_MAX*2.0)-1.0);
+}