1.1 --- a/src/metasurf.c	Tue Oct 25 13:30:03 2011 +0300
     1.2 +++ b/src/metasurf.c	Tue Oct 25 23:21:32 2011 +0300
     1.3 @@ -38,6 +38,9 @@
     1.4  	msurf_vertex_func_t vertex;
     1.5  	msurf_normal_func_t normal;
     1.6  
     1.7 +	float dx, dy, dz;
     1.8 +	int flip;
     1.9 +
    1.10  	vec3 vbuf[3];
    1.11  	int nverts;
    1.12  };
    1.13 @@ -81,9 +84,28 @@
    1.14  	ms->res[0] = ms->res[1] = ms->res[2] = 40;
    1.15  	ms->nverts = 0;
    1.16  
    1.17 +	ms->dx = ms->dy = ms->dz = 0.001;
    1.18 +	ms->flip = 0;
    1.19 +
    1.20  	return 0;
    1.21  }
    1.22  
    1.23 +void msurf_inside(struct metasurface *ms, int inside)
    1.24 +{
    1.25 +	switch(inside) {
    1.26 +	case MSURF_GREATER:
    1.27 +		ms->flip = 0;
    1.28 +		break;
    1.29 +
    1.30 +	case MSURF_LESS:
    1.31 +		ms->flip = 1;
    1.32 +		break;
    1.33 +
    1.34 +	default:
    1.35 +		fprintf(stderr, "msurf_inside expects MSURF_GREATER or MSURF_LESS\n");
    1.36 +	}
    1.37 +}
    1.38 +
    1.39  void msurf_eval_func(struct metasurface *ms, msurf_eval_func_t func)
    1.40  {
    1.41  	ms->eval = func;
    1.42 @@ -219,6 +241,10 @@
    1.43  	vec3 vert[12];
    1.44  	unsigned int code = mc_bitcode(val, ms->thres);
    1.45  
    1.46 +	if(ms->flip) {
    1.47 +		code = ~code & 0xff;
    1.48 +	}
    1.49 +
    1.50  	if(mc_edge_table[code] == 0) {
    1.51  		return;
    1.52  	}
    1.53 @@ -238,6 +264,21 @@
    1.54  	for(i=0; mc_tri_table[code][i] != -1; i+=3) {
    1.55  		for(j=0; j<3; j++) {
    1.56  			float *v = vert[mc_tri_table[code][i + j]];
    1.57 +
    1.58 +			if(ms->normal) {
    1.59 +				float dfdx, dfdy, dfdz;
    1.60 +				dfdx = ms->eval(v[0] - ms->dx, v[1], v[2]) - ms->eval(v[0] + ms->dx, v[1], v[2]);
    1.61 +				dfdy = ms->eval(v[0], v[1] - ms->dy, v[2]) - ms->eval(v[0], v[1] + ms->dy, v[2]);
    1.62 +				dfdz = ms->eval(v[0], v[1], v[2] - ms->dz) - ms->eval(v[0], v[1], v[2] + ms->dz);
    1.63 +
    1.64 +				if(ms->flip) {
    1.65 +					dfdx = -dfdx;
    1.66 +					dfdy = -dfdy;
    1.67 +					dfdz = -dfdz;
    1.68 +				}
    1.69 +				ms->normal(dfdx, dfdy, dfdz);
    1.70 +			}
    1.71 +
    1.72  			ms->vertex(v[0], v[1], v[2]);
    1.73  		}
    1.74  	}