nuclear@5: #include <vector>
nuclear@5: #include "opengl.h"
nuclear@5: #include "mballs.h"
nuclear@5: #include "metasurf.h"
nuclear@5: #include "vmath/vmath.h"
nuclear@5: 
nuclear@5: struct MetaBall {
nuclear@5: 	Vector3 pos;
nuclear@5: 	float orbit;
nuclear@5: 	float energy;
nuclear@5: 	float phase_offs;
nuclear@5: };
nuclear@5: 
nuclear@5: #define VOL_SZ			2
nuclear@5: #define MBALL_GRID_SZ	50
nuclear@5: 
nuclear@5: static void update();
nuclear@5: static float calc_field(float x, float y, float z);
nuclear@5: static float eval(float x, float y, float z);
nuclear@5: static void vertex(float x, float y, float z);
nuclear@5: static void normal(float x, float y, float z);
nuclear@5: 
nuclear@5: static float grid[MBALL_GRID_SZ][MBALL_GRID_SZ][MBALL_GRID_SZ];
nuclear@5: static std::vector<MetaBall> balls;
nuclear@5: static struct metasurface *msurf;
nuclear@5: 
nuclear@5: bool mball_init()
nuclear@5: {
nuclear@5: 	static const float bbmin = -VOL_SZ / 2.0;
nuclear@5: 	static const float bbmax = VOL_SZ / 2.0;
nuclear@5: 
nuclear@5: 	if(!(msurf = msurf_create())) {
nuclear@5: 		return false;
nuclear@5: 	}
nuclear@5: 	msurf_threshold(msurf, 10);
nuclear@5: 	msurf_resolution(msurf, MBALL_GRID_SZ, MBALL_GRID_SZ, MBALL_GRID_SZ);
nuclear@5: 	msurf_bounds(msurf, bbmin, bbmin, bbmin, bbmax, bbmax, bbmax);
nuclear@5: 	msurf_eval_func(msurf, eval);
nuclear@5: 	msurf_vertex_func(msurf, vertex);
nuclear@5: 	//msurf_normal_func(msurf, normal);
nuclear@5: 
nuclear@5: 	for(int i=0; i<10; i++) {
nuclear@5: 		MetaBall mb;
nuclear@5: 		mb.orbit = 0.25 * rand() / (float)RAND_MAX + 0.35;
nuclear@5: 		mb.energy = 0.2 * rand() / (float)RAND_MAX + 0.15;
nuclear@5: 		mb.phase_offs = rand() / (float)RAND_MAX * M_PI * 2.0;
nuclear@5: 		balls.push_back(mb);
nuclear@5: 	}
nuclear@5: 
nuclear@5: 	return true;
nuclear@5: }
nuclear@5: 
nuclear@5: void mball_render()
nuclear@5: {
nuclear@5: 	update();
nuclear@5: 
nuclear@5: 	glMatrixMode(GL_MODELVIEW);
nuclear@5: 	glPushMatrix();
nuclear@5: 	glScalef(4.0, 4.0, 4.0);
nuclear@5: 
nuclear@5: 	glBegin(GL_TRIANGLES);
nuclear@5: 	msurf_polygonize(msurf);
nuclear@5: 	glEnd();
nuclear@5: 
nuclear@5: 	glPopMatrix();
nuclear@5: }
nuclear@5: 
nuclear@5: 
nuclear@5: static void update()
nuclear@5: {
nuclear@5: 	unsigned int msec = glutGet(GLUT_ELAPSED_TIME);
nuclear@5: 	float sec = msec / 1000.0;
nuclear@5: 
nuclear@5: 	for(size_t i=0; i<balls.size(); i++) {
nuclear@5: 		float t = sec + balls[i].phase_offs;
nuclear@5: 		balls[i].pos.x = cos(t * 1.8) * balls[i].orbit;
nuclear@5: 		balls[i].pos.z = sin(t * 1.2) * balls[i].orbit;
nuclear@5: 		balls[i].pos.y = (sin(t) + cos(t * 2.0) / 2.0 + sin(t * 3.0) / 3.0) * 0.45;
nuclear@5: 	}
nuclear@5: 
nuclear@5: 	for(int i=0; i<MBALL_GRID_SZ; i++) {
nuclear@5: 		float x = (float)i / (float)MBALL_GRID_SZ * 2.0 - 1.0;
nuclear@5: 		for(int j=0; j<MBALL_GRID_SZ; j++) {
nuclear@5: 			float y = (float)j / (float)MBALL_GRID_SZ * 2.0 - 1.0;
nuclear@5: 			for(int k=0; k<MBALL_GRID_SZ; k++) {
nuclear@5: 				float z = (float)k / (float)MBALL_GRID_SZ * 2.0 - 1.0;
nuclear@5: 				grid[i][j][k] = calc_field(x, y, z);
nuclear@5: 			}
nuclear@5: 		}
nuclear@5: 	}
nuclear@5: }
nuclear@5: 
nuclear@5: static float calc_field(float x, float y, float z)
nuclear@5: {
nuclear@5: 	Vector3 pt(x, y, z);
nuclear@5: 
nuclear@5: 	float sum = 0.0f;
nuclear@5: 	for(size_t i=0; i<balls.size(); i++) {
nuclear@5: 		float dist_sq = (balls[i].pos - pt).length_sq();
nuclear@5: 		if(dist_sq > 1e-6) {
nuclear@5: 			sum += balls[i].energy / dist_sq;
nuclear@5: 		} else {
nuclear@5: 			sum += 1000.0;
nuclear@5: 		}
nuclear@5: 	}
nuclear@5: 	return sum;
nuclear@5: }
nuclear@5: 
nuclear@5: static inline int clamp(int x, int a, int b)
nuclear@5: {
nuclear@5: 	return x < a ? a : (x > b ? b : x);
nuclear@5: }
nuclear@5: 
nuclear@5: static float eval(float x, float y, float z)
nuclear@5: {
nuclear@5: 	int cell_x = clamp((int)((x / VOL_SZ + 0.5) * MBALL_GRID_SZ), 0, MBALL_GRID_SZ - 1);
nuclear@5: 	int cell_y = clamp((int)((y / VOL_SZ + 0.5) * MBALL_GRID_SZ), 0, MBALL_GRID_SZ - 1);
nuclear@5: 	int cell_z = clamp((int)((z / VOL_SZ + 0.5) * MBALL_GRID_SZ), 0, MBALL_GRID_SZ - 1);
nuclear@5: 
nuclear@5: 	return grid[cell_x][cell_y][cell_z];
nuclear@5: }
nuclear@5: 
nuclear@5: static void vertex(float x, float y, float z)
nuclear@5: {
nuclear@5: 	float delta = (float)VOL_SZ / (float)MBALL_GRID_SZ;
nuclear@5: 
nuclear@5: 	float dfdx = calc_field(x - delta, y, z) - calc_field(x + delta, y, z);
nuclear@5: 	float dfdy = calc_field(x, y - delta, z) - calc_field(x, y + delta, z);
nuclear@5: 	float dfdz = calc_field(x, y, z - delta) - calc_field(x, y, z + delta);
nuclear@5: 
nuclear@5: 	float len = sqrt(dfdx * dfdx + dfdy * dfdy + dfdz * dfdz);
nuclear@5: 
nuclear@5: 	glNormal3f(dfdx / len, dfdy / len, dfdz / len);
nuclear@5: 	glVertex3f(x, y, z);
nuclear@5: }
nuclear@5: 
nuclear@5: static void normal(float x, float y, float z)
nuclear@5: {
nuclear@5: 	glNormal3f(x, y, z);
nuclear@5: }