#include "shader.h"
#include "miaux.h"

int voxel_dataset_version(void) { return 1; }

#define MAX_DATASET_SIZE 400*400*400

typedef struct {
    int width, height, depth;
    float block[MAX_DATASET_SIZE];
} voxel_data;


float voxel_value(voxel_data *voxels, float x, float y, float z)
{
    return voxels->block[ 
        ((int)(z + .5)) * voxels->depth * voxels->height +
        ((int)(y + .5)) * voxels->height +
        ((int)(x + .5)) ];
}

struct voxel_density {
    miTag filename_tag;
    miVector min_point;
    miVector max_point;
    miColor color;
};

DLLEXPORT
int voxel_density_version(void) { return 1; }

DLLEXPORT
miBoolean voxel_density_init(
    miState *state, struct voxel_density *params,
    miBoolean *instance_init_required)
{
    if (!params) {  /* Main shader init (not an instance): */
        *instance_init_required = miTRUE;
    } else {        /* Instance initialization: */
        char* filename = 
            miaux_tag_to_string(*mi_eval_tag(&params->filename_tag), NULL);
        if (filename) {
            voxel_data *voxels = 
                miaux_user_memory_pointer(state, sizeof(voxel_data));
            miaux_read_volume_block(
                filename, &voxels->width, &voxels->height, &voxels->depth, 
                voxels->block);
            mi_progress("Voxel dataset: %dx%dx%d", 
                        voxels->width, voxels->height, voxels->depth);
        }
    }
    return miTRUE;
}


DLLEXPORT
miBoolean voxel_density_exit(miState *state, void *params)
{
    return miaux_release_user_memory("voxel_density", state, params);
}


DLLEXPORT
miBoolean voxel_density ( 
    miScalar *result, miState *state, struct voxel_density *params  )
{
    miVector *min_point = mi_eval_vector(&params->min_point);
    miVector *max_point = mi_eval_vector(&params->max_point);
    miVector *p = &state->point;

    if (miaux_point_inside(p, min_point, max_point)) {
        float x, y, z;
        voxel_data *voxels = miaux_user_memory_pointer(state, 0);
        x = miaux_fit(p->x, min_point->x, max_point->x, 0, voxels->width-1);
        y = miaux_fit(p->y, min_point->y, max_point->y, 0, voxels->height-1);
        z = miaux_fit(p->z, min_point->z, max_point->z, 0, voxels->depth-1);
        *result = voxel_value(voxels, x, y, z);
    } else 
        *result = 0.0;

    return miTRUE;
}