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|
/*
* Copyright 2011 Vincent Sanders <vince@kyllikki.org>
*
* Licenced under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
*
* This file is part of png23d.
*
* Routines to handle mesh generation
*/
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include "option.h"
#include "bitmap.h"
#include "mesh.h"
#include "mesh_gen.h"
#include "mesh_math.h"
enum faces {
FACE_LEFT = 1,
FACE_RIGHT = 2,
FACE_TOP = 4,
FACE_BOT = 8,
FACE_FRONT = 16,
FACE_BACK = 32,
};
/** calculate which faces of a cube are adjacent solid cubes
*/
static uint32_t
mesh_gen_get_face(bitmap *bm,
unsigned int x,
unsigned int y,
unsigned int z,
struct options *options)
{
uint32_t faces = 0;
unsigned int transparent = options->transparent;
unsigned int pxl_lvl;
uint8_t pxl_val;
#define Z_LVL_VAL(val) ((val) * (256 / options->levels))
/* value at which pixel is transparent */
pxl_lvl = Z_LVL_VAL(z);
/* pixel value at sample point */
pxl_val = bm->data[(y * bm->width) + x];
if ((pxl_val == transparent) ||
(pxl_val < pxl_lvl)) {
/* only opaque squares can have faces */
return faces;
}
/* start with all faces set */
faces = FACE_TOP | FACE_BOT |
FACE_BACK | FACE_FRONT |
FACE_LEFT | FACE_RIGHT;
/* z axis faces */
/* only the bottom layer has a front face */
if (z > 0) {
faces = faces & ~FACE_FRONT;
}
if ((z < (options->levels - 1)) &&
(pxl_val >= Z_LVL_VAL(z + 1))) {
faces = faces & ~FACE_BACK;
}
/* x axis faces */
if (x > 0) {
/* pixel value left of sample point */
pxl_val = bm->data[(y * bm->width) + (x - 1)];
if ((pxl_val != transparent) &&
(pxl_val >= pxl_lvl)) {
faces = faces & ~FACE_LEFT;
}
}
if (x < (bm->width - 1)) {
/* pixel value right of sample point */
pxl_val = bm->data[(y * bm->width) + (x + 1)];
if ((pxl_val != transparent) &&
(pxl_val >= pxl_lvl)) {
faces = faces & ~FACE_RIGHT;
}
}
if (y > 0) {
pxl_val = bm->data[((y - 1) * bm->width) + x ];
if ((pxl_val != transparent) &&
(pxl_val >= pxl_lvl)) {
faces = faces & ~FACE_TOP;
}
}
if (y < (bm->height - 1)) {
pxl_val = bm->data[((y + 1) * bm->width) + x ];
if ((pxl_val != transparent) &&
(pxl_val >= pxl_lvl)) {
faces = faces & ~FACE_BOT;
}
}
return faces;
}
/** add a facet to the mesh */
static bool
mesh_add_facet(struct mesh *mesh,
float vx0,float vy0, float vz0,
float vx1,float vy1, float vz1,
float vx2,float vy2, float vz2)
{
struct facet *newfacet;
bool degenerate = false;
if ((mesh->fcount + 1) > mesh->falloc) {
/* array needs extending */
mesh->f = realloc(mesh->f, (mesh->falloc + 1000) * sizeof(struct facet));
mesh->falloc += 1000;
}
newfacet = mesh->f + mesh->fcount;
newfacet->v[0].x = vx0;
newfacet->v[0].y = vy0;
newfacet->v[0].z = vz0;
newfacet->v[1].x = vx1;
newfacet->v[1].y = vy1;
newfacet->v[1].z = vz1;
newfacet->v[2].x = vx2;
newfacet->v[2].y = vy2;
newfacet->v[2].z = vz2;
degenerate = pnt_normal(&newfacet->n,
&newfacet->v[0],
&newfacet->v[1],
&newfacet->v[2]);
/* do not add degenerate facets */
if (!degenerate) {
mesh->fcount++;
}
return degenerate;
}
#define ADDF(xa,ya,za,xb,yb,zb,xc,yc,zc) mesh_add_facet(mesh, \
x + (xa * width), y + (ya * height), z + (za * depth), \
x + (xb * width), y + (yb * height), z + (zb * depth), \
x + (xc * width), y + (yc * height), z + (zc * depth))
/* generates cube facets for a location */
static void
mesh_gen_cube(struct mesh *mesh,
float x, float y, float z,
float width, float height, float depth,
uint32_t faces)
{
if (faces != 0) {
mesh->cubes++;
}
switch (faces & 0xf) {
case 0: /* empty */
break;
case FACE_LEFT:
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
break;
case FACE_RIGHT:
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case (FACE_LEFT | FACE_RIGHT) :
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case FACE_TOP:
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
break;
case (FACE_TOP | FACE_LEFT):
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
break;
case (FACE_TOP | FACE_RIGHT):
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case (FACE_TOP | FACE_LEFT | FACE_RIGHT):
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case FACE_BOT:
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
break;
case (FACE_BOT | FACE_LEFT):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
break;
case (FACE_BOT | FACE_RIGHT):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case (FACE_BOT | FACE_LEFT | FACE_RIGHT) :
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case (FACE_BOT | FACE_TOP):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
break;
case (FACE_BOT | FACE_TOP | FACE_LEFT):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
break;
case (FACE_BOT | FACE_TOP | FACE_RIGHT):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case (FACE_BOT | FACE_TOP | FACE_LEFT | FACE_RIGHT):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
}
if ((faces & FACE_FRONT) != 0) {
ADDF(0,0,0, 0,1,0, 1,0,0);
ADDF(0,1,0, 1,1,0, 1,0,0);
}
if ((faces & FACE_BACK) != 0) {
ADDF(0,0,1, 1,0,1, 0,1,1);
ADDF(0,1,1, 1,0,1, 1,1,1);
}
}
/* generates smoothed facets for a location
*
* appies marching squares (ish) to generate facets
*
* @todo make this table driven as a 64 entry switch is out of hand
*/
static void
mesh_gen_marching_squares(struct mesh *mesh,
float x, float y, float z,
float width, float height, float depth,
uint32_t faces)
{
if (faces != 0) {
mesh->cubes++;
}
switch (faces & 0xf) {
case 0: /* empty */
break;
case FACE_LEFT:
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
break;
case FACE_RIGHT:
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case (FACE_LEFT | FACE_RIGHT) :
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case FACE_TOP:
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
break;
case (FACE_TOP | FACE_LEFT):
ADDF(0,0,0, 0,0,1, 1,1,0);
ADDF(1,1,0, 0,0,1, 1,1,1);
if ((faces & FACE_FRONT) != 0) {
ADDF(0,0,0, 1,1,0, 1,0,0);
faces = faces & ~FACE_FRONT;
}
if ((faces & FACE_BACK) != 0) {
ADDF(0,0,1, 1,0,1, 1,1,1);
faces = faces & ~FACE_BACK;
}
break;
case (FACE_TOP | FACE_RIGHT):
ADDF(1,0,0, 0,1,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,0,1);
if ((faces & FACE_FRONT) != 0) {
ADDF(1,0,0, 0,0,0, 0,1,0);
faces = faces & ~FACE_FRONT;
}
if ((faces & FACE_BACK) != 0) {
ADDF(1,0,1, 0,1,1, 0,0,1);
faces = faces & ~FACE_BACK;
}
break;
case (FACE_TOP | FACE_LEFT | FACE_RIGHT):
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case FACE_BOT:
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
break;
case (FACE_BOT | FACE_LEFT):
ADDF(0,1,0, 1,0,0, 1,0,1);
ADDF(0,1,0, 1,0,1, 0,1,1);
if ((faces & FACE_FRONT) != 0) {
ADDF(1,0,0, 0,1,0, 1,1,0);
faces = faces & ~FACE_FRONT;
}
if ((faces & FACE_BACK) != 0) {
ADDF(1,0,1, 1,1,1, 0,1,1);
faces = faces & ~FACE_BACK;
}
break;
case (FACE_BOT | FACE_RIGHT):
ADDF(0,0,0, 1,1,0, 0,0,1);
ADDF(0,0,1, 1,1,0, 1,1,1);
if ((faces & FACE_FRONT) != 0) {
ADDF(0,0,0, 0,1,0, 1,1,0);
faces = faces & ~FACE_FRONT;
}
if ((faces & FACE_BACK) != 0) {
ADDF(0,0,1, 1,1,1, 0,1,1);
faces = faces & ~FACE_BACK;
}
break;
case (FACE_BOT | FACE_LEFT | FACE_RIGHT) :
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case (FACE_BOT | FACE_TOP):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
break;
case (FACE_BOT | FACE_TOP | FACE_LEFT):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
break;
case (FACE_BOT | FACE_TOP | FACE_RIGHT):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
case (FACE_BOT | FACE_TOP | FACE_LEFT | FACE_RIGHT):
ADDF(0,0,0, 1,0,0, 0,0,1);
ADDF(0,0,1, 1,0,0, 1,0,1);
ADDF(0,1,0, 0,1,1, 1,1,0);
ADDF(0,1,1, 1,1,1, 1,1,0);
ADDF(0,0,0, 0,0,1, 0,1,0);
ADDF(0,1,0, 0,0,1, 0,1,1);
ADDF(1,0,0, 1,1,0, 1,0,1);
ADDF(1,1,0, 1,1,1, 1,0,1);
break;
}
if ((faces & FACE_FRONT) != 0) {
ADDF(0,0,0, 0,1,0, 1,0,0);
ADDF(0,1,0, 1,1,0, 1,0,0);
}
if ((faces & FACE_BACK) != 0) {
ADDF(0,0,1, 1,0,1, 0,1,1);
ADDF(0,1,1, 1,0,1, 1,1,1);
}
}
typedef void (meshgenerator)(struct mesh *mesh,
float x, float y, float z,
float width, float height, float depth,
uint32_t faces);
/* generate maching squares
*
* this is a simple 2d extrusion of modified marching squares
* http://en.wikipedia.org/wiki/Marching_cubes
*
* consider each pixel in the raster image:
* - generate a bitfield indicating on which sides of the pixel faces need to
* be covered to generate a convex manifold.
* - add triangle facets to list for each face present
*
*/
static bool mesh_gen_squares(struct mesh *mesh, bitmap *bm, options *options)
{
unsigned int yloop;
unsigned int xloop;
unsigned int zloop;
uint32_t faces;
meshgenerator *meshgen;
if (options->levels == 1) {
meshgen = &mesh_gen_marching_squares;
} else {
meshgen = &mesh_gen_cube;
}
for (zloop = 0; zloop < options->levels; zloop++) {
for (yloop = 0; yloop < bm->height; yloop++) {
for (xloop = 0; xloop < bm->width; xloop++) {
faces = mesh_gen_get_face(bm, xloop, yloop, zloop, options);
meshgen(mesh, xloop, -(float)yloop, zloop, 1, 1, 1, faces);
}
}
}
return true;
}
/* generate cubic mesh
*
* consider each pixel in the raster image:
* - generate a bitfield indicating on which sides of the pixel faces need to
* be covered to generate a convex manifold.
* - add triangle facets to list for each face present
*
* @todo This could probably be better converted to a marching cubes solution
* instead http://en.wikipedia.org/wiki/Marching_cubes
*/
static bool mesh_gen_cubes(struct mesh *mesh, bitmap *bm, options *options)
{
unsigned int yloop;
unsigned int xloop;
unsigned int zloop;
uint32_t faces;
for (zloop = 0; zloop < options->levels; zloop++) {
for (yloop = 0; yloop < bm->height; yloop++) {
for (xloop = 0; xloop < bm->width; xloop++) {
faces = mesh_gen_get_face(bm, xloop, yloop, zloop, options);
mesh_gen_cube(mesh, xloop, -(float)yloop, zloop, 1, 1, 1, faces);
}
}
}
return true;
}
static inline float
surfacegen_calcp(bitmap *bm,
int x,
int y,
options *options)
{
uint8_t pxl_val;
int res;
/* range check, casts are safe because value cannot be -ve from previous
* test.
*/
if ((x < 0) || ((unsigned int)x >= bm->width) ||
(y < 0) || ((unsigned int)y >= bm->height)) {
return 0.0f;
}
pxl_val = bm->data[(y * bm->width) + x];
if (pxl_val == options->transparent) {
return 0.0f;
}
res = 1+(pxl_val + 1) / (256 / options->levels);
return res;
}
#define ADDSF(xa,ya,za,xb,yb,zb,xc,yc,zc) mesh_add_facet(mesh, \
x + (xa * width), y + (ya * height), za * points[xa][ya], \
x + (xb * width), y + (yb * height), zb * points[xb][yb], \
x + (xc * width), y + (yc * height), zc * points[xc][yc])
static void
gen_surface(struct mesh *mesh,
float x, float y,
float width, float height,
bool evenp, float points[2][2])
{
if (evenp) {
if ( (points[0][0] != 0) ||
(points[1][1] != 0) ||
(points[0][1] != 0)) {
/* top surface */
ADDSF(0,0,1, 0,1,1, 1,1,1);
/* flat bottom */
ADDSF(0,0,0, 1,1,0, 0,1,0);
}
if ( (points[0][0] != 0) ||
(points[1][0] != 0) ||
(points[1][1] != 0)) {
/* top surface */
ADDSF(0,0,1, 1,1,1, 1,0,1);
/* flat bottom */
ADDSF(0,0,0, 1,0,0, 1,1,0);
}
} else {
if ( (points[0][0] != 0) ||
(points[1][0] != 0) ||
(points[0][1] != 0)) {
/* top surface */
ADDSF(0,0,1, 0,1,1, 1,0,1);
/* flat bottom */
ADDSF(0,0,0, 1,0,0, 0,1,0);
}
if ( (points[1][0] != 0) ||
(points[1][1] != 0) ||
(points[0][1] != 0)) {
/* top surface */
ADDSF(1,0,1, 0,1,1, 1,1,1);
/* flat bottom */
ADDSF(1,0,0, 1,1,0, 0,1,0);
}
}
}
static bool mesh_gen_surface(struct mesh *mesh, bitmap *bm, options *options)
{
unsigned int yloop;
unsigned int xloop;
float points[2][2];
for (yloop = 0; yloop <= bm->height; yloop++) {
for (xloop = 0; xloop <= bm->width; xloop++) {
points[0][0] = surfacegen_calcp(bm, xloop - 1, yloop - 1, options);
points[1][0] = surfacegen_calcp(bm, xloop, yloop - 1, options);
points[0][1] = surfacegen_calcp(bm, xloop - 1, yloop, options);
points[1][1] = surfacegen_calcp(bm, xloop, yloop, options);
gen_surface(mesh,
xloop, -(float)yloop,
1, -1,
(((xloop + yloop) & 1) == 0),
points);
}
}
return true;
}
/* exported method documented in mesh_gen.h */
bool
mesh_from_bitmap(struct mesh *mesh, bitmap *bm, options *options)
{
bool res = false;
mesh->height = bm->height;
mesh->width = bm->width;
INFO("Generating mesh from bitmap of size %dx%d with %d levels\n",
bm->width, bm->height, options->levels);
switch (options->finish) {
case FINISH_SURFACE:
res = mesh_gen_surface(mesh, bm, options);
break;
case FINISH_SMOOTH:
res = mesh_gen_squares(mesh, bm, options);
break;
case FINISH_CUBE:
res = mesh_gen_cubes(mesh, bm, options);
break;
case FINISH_RECT:
fprintf(stderr, "Cannot generate mesh with Rectangular Cuboid finish\n");
break;
}
return res;
}
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