i have made a view frustum from scratch in javascript. i have been having trouble with objects that the camera is place within and also facing away from.
an example of the problem is below
ive been stuck on this for months with little help, chatgpt recommended that i switch to a right handed corodinate system, so i did, but it didnt seem to fix the problem.
my proccess for putting pixels on the screen is described below
step 1 = cross product with camera matrix
step 2 = cross product with projection matrix
step 3 = divide co-ordinates by their own w co-ord (normalize w to 1)
step 3.5 = im currently skipping culling. culling would go here, but since my object is made of multiple vertices i cant cull a vertex just because its offscreen as it forms part of a whole object, and that would deform the rest of the object
step 4 = cross product with projection to screen matrix
below shows how the co-ordinates of 1 vertex changes with each step
co-ordinates of vertex before projection
[5.00,9.00,10.00,1.00]
good projection (tile is good)
step 1 = [5, 9, -4.799999999999979, 10]
step 2 = [-8.660254038143698, 15.588457268658656, 15.353535353535376, 4.799999999999979]
step 3 = [-1.8042195912799448, 3.2475952643039006, 3.198653198653217, 1]
step 4 = [-120.63293869199174, 637.1392896455851, 3.198653198653217, 1]
pixels = -120.63293869199174,637.1392896455851
#############################
bad projection from within the object (tile is deformed)
step 1 = [5, 9, 0.6000000000000014, 10]
step 2 = [-8.660254038143698, 15.588457268658656, 20.808080808080813, -0.6000000000000014]
step 3 = [14.433756730239462, -25.980762114431034, -34.68013468013461, 1]
step 4 = [2315.0635095359194, -3747.114317164655, -34.68013468013461, 1]
pixels = 2315.0635095359194,-3747.114317164655
###############################
bad projection from behind (tile appears on the ceiling, when A it should be on the floor and B it shouldn't be visible)
step 1 = [5, 9, 16.800000000000004, 10]
step 2 = [-8.660254038143698, 15.588457268658656, 37.17171717171718, -16.800000000000004]
step 3 = [0.5154913117942677, -0.9278843612296817, -2.2126022126022122, 1]
step 4 = [227.32369676914016, 10.817345815547753, -2.2126022126022122, 1]
pixels = 227.32369676914016, 10.817345815547753
does anyone know which step could be wrong or need changing in situation 2 and 3? and why?
below is a minimal (i know its 500 lines... but its about as minimal as i can get it) just open it in a browser and use wasd to control it.
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/mathjs/11.3.3/math.js"></script>
<script async src="https://unpkg.com/es-module-shims#1.3.6/dist/es-module-shims.js"></script>
</head>
<body>
<div id="canvas div" style = "position: relative; left: 0px; float:left; top: 0px;" >
<h1> first person below </h1>
<canvas id="mi_canvas" width="300" height="300" style="border-style: solid;"></canvas> <br>
<h1> radar below </h1>
<canvas id="radar_canvas" width="300" height="300" style="border-style: solid;"></canvas>
</div>
<div id="big info div" style = "position: relative; left: 310px; float:left; float:top; top: 0px; width:400px;" >
<div id = "info_1111"> </div><br>
</div>
<script>
var floor_y_pos = 9
canvas = document.getElementById("mi_canvas");
ctx = canvas.getContext("2d");
radar = document.getElementById("radar_canvas");
radar_ctx = radar.getContext("2d");
render_distance = 1000;
fov = math.pi / 2
class Projection{
constructor(){
var NEAR = player.near_plane
var FAR = player.far_plane
var RIGHT = Math.tan(player.h_fov/2)
var LEFT = - RIGHT
var TOP = Math.tan(player.v_fov /2)
var BOTTOM = -TOP
var m00 = 2*NEAR / (RIGHT - LEFT)
var m02 = (RIGHT + LEFT)/(RIGHT - LEFT)
var m11 = 2*NEAR / (TOP - BOTTOM)
var m12 = (TOP + BOTTOM) /(TOP - BOTTOM)
var m22 = (FAR * NEAR) / (FAR - NEAR)
var m23 = -2 * NEAR * FAR / (FAR-NEAR)
this.projection_matrix = [
[-m00,0,m02,0],
[0,m11,0,0],
[m02,m12,-m22,-1],
[0,0,m23,0]
]
var HW=player.H_WIDTH
var HH = player.H_HEIGHT
this.to_screen_matrix = [
[HW,0,0,0],
[0,HH,0,0],
[0,0,1,0],
[HW,HH,0,1]
]
}
}
function multiply(a, b) {
var aNumRows = a.length, aNumCols = a[0].length,
bNumRows = b.length, bNumCols = b[0].length,
m = new Array(aNumRows); // initialize array of rows
for (var r = 0; r < aNumRows; ++r) {
m[r] = new Array(bNumCols); // initialize the current row
for (var c = 0; c < bNumCols; ++c) {
m[r][c] = 0; // initialize the current cell
for (var i = 0; i < aNumCols; ++i) {
m[r][c] += a[r][i] * b[i][c];
}
}
}
return m;
}
function mi_position_matrix_multiplier(A, B)
{
var new_matrix = []
for (var new_num_ind = 0; new_num_ind < A.length; ++new_num_ind)
{
this_num = 0;
for (var a_ind = 0; a_ind < A.length; ++a_ind)
{
this_num += (A[a_ind] * B[a_ind][new_num_ind])
}
// console.log("just added this num to my new matrix = "+this_num.toString())
new_matrix.push(this_num)
}
return new_matrix;
}
function pythagoras(thing1, thing2)
{
dist = (((thing1[0]-thing2[0])**2)+((thing1[1]-thing2[1])**2))**0.5
return dist
}
class vertex{
constructor(x, y,z , id){
this.id = id
this.position = [x,y,z,1]
this.min_dist = 1.5 // minimum possible distance between player and object
}
is_this_object_behind_player(){
var arrow_length = 0.0001;
var pointing_position = [player.position[0]+(player.forward[0]*arrow_length) , player.position[2]-(player.forward[2]*arrow_length)]
var dist1 = pythagoras([this.position[0],this.position[2]], pointing_position)
var dist2 = pythagoras([this.position[0],this.position[2]], [player.position[0],player.position[2]])
if (dist1 < dist2){
return true;}
else if (dist1 > dist2){
return false;}
else{console.log(" else ");}
}
screen_projection(){
var position = mi_position_matrix_multiplier(this.position , player.camera_matrix())
console.log(position+" = position , which is a cross product of this.position"+this.position+" & "+ player.camera_matrix()+ " = player.camera_matrix()")
update_matrix_info_debug("camera_matrix",player.camera_matrix())
update_matrix_info_debug("position", position)
position = mi_position_matrix_multiplier(position , projection.projection_matrix) // does this just convert the position to cameras reference frame.
console.log(position+" = position , which is a cross product of position"+position+" & "+ projection.projection_matrix+ " = projection.projection_matrix")
update_matrix_info_debug("projection_matrix",projection.projection_matrix)
update_matrix_info_debug("position after being multiplied by proj matrix", position)
// if so then i image to screen matrix is insufficient
for (let i = 0; i < position.length; i++) {
position[i] = position[i]/position[3]
}
console.log(position+" = position after being normaslized")
for (let i = 0; i < position.length; i++) {
if (i != 9787781){
console.log(i+" =-= "+position[i])
if (this.is_this_object_behind_player()){for (let ii = 0; ii < position.length; ii++) {position[ii] = -999999999;} console.log("culling1")}
if (position[i] > 2){for (let ii = 0; ii < position.length; ii++) {position[ii] = -9999;} console.log("culling2")}
if (position[i] < -2){for (let ii = 0; ii < position.length; ii++) {position[ii] = -9999;} console.log("culling3")}
}
} // also all examples say set position = 0 if culling
console.log(position+" = position after being culled")
position = mi_position_matrix_multiplier(position , projection.to_screen_matrix)
console.log(position+" = position after being multiplied by "+projection.to_screen_matrix+ " = projection.to_screen_matrix")
update_matrix_info_debug("projection.to_screen_matrix",projection.to_screen_matrix)
update_matrix_info_debug("position after being multiplied by projection.to_screen_matrix", position)
ctx.beginPath();
var scale_multiplier = (render_distance / pythagoras([this.position[0],this.position[2]] , [player.position[0],player.position[2]]))*1.5
var arrow_size = 0.02 * scale_multiplier;
ctx.moveTo(position[0]-arrow_size ,position[1]+arrow_size);
ctx.lineTo(position[0]+arrow_size ,position[1]-arrow_size);
ctx.moveTo(position[0]+arrow_size ,position[1]+arrow_size);
ctx.lineTo(position[0]-arrow_size, position[1]-arrow_size);
ctx.stroke();
}
return_screen_projection(dont_cull = false){
var position = mi_position_matrix_multiplier(this.position , player.camera_matrix())
position = mi_position_matrix_multiplier(position , projection.projection_matrix) // does this just convert the position to cameras reference frame.
for (let i = 0; i < position.length; i++) {
position[i] = position[i]/position[3]
}
position = mi_position_matrix_multiplier(position , projection.to_screen_matrix)
return [position[0],position[1]]
}
}
class player{
constructor(){
this.position =[0,0,0,1.0]
this.forward = [0,0,1,1]
this.up = [0,1,0,1]
this.right =[1,0,0,1]
this.h_fov = 3.1415926535/3
this.v_fov = this.h_fov * (canvas.height / canvas.width)
this.near_plane = 1
this.far_plane = 100
this.moving_speed = 0.2
this.rotation_speed = 0.1
this.H_WIDTH = canvas.width/2
this.H_HEIGHT = canvas.height/2
this.anglePitch = 0
this.angleYaw = 0
}
set_camera_angle(){
var rotate = multiply(rotate_x(this.anglePitch) , rotate_y(this.angleYaw))
this.forward = [0, 0, 1, 1]
this.up = [0, 1, 0, 1]
this.right = [1, 0, 0, 1]
this.forward = mi_position_matrix_multiplier(this.forward , rotate)
this.right = mi_position_matrix_multiplier(this.right , rotate)
this.up = mi_position_matrix_multiplier(this.up , rotate)
}
camera_yaw(angle){
this.angleYaw += angle}
translate_matrix(self){
var x = this.position[0];
var y = this.position[1];
var z = this.position[2];
var w = this.position[3];
return [
[1,0,0,0],
[0,1,0,1],
[0,0,1,0],
[-x,-y,z, 1]
]}
rotate_matrix(){
var rx = this.right[0]
var ry = this.right[1]
var rz = this.right[2]
var w = this.right[3]
var fx = this.forward[0]
var fy = this.forward[1]
var fz = this.forward[2]
var w = this.forward[3]
var ux = this.up[0]
var uy = this.up[1]
var uz = this.up[2]
var w = this.up[3]
return [
[rx,ux,fx,0],
[ry,uy,fy,0],
[rz,uz,fz,0],
[0,0,0,1]
]
}
camera_matrix(){
return multiply(this.translate_matrix(), this.rotate_matrix());
}
check_min_distance_isnt_overcome_by_this_move(dx, dy){
var can_move = true;
console.log(" zzzzzzzzzzzzz ")
for (let i = 0; i < objects.length; i++) {
var dist=Math.abs(pythagoras([objects[i].position[0], objects[i].position[2]] , [this.position[0], this.position[2]]))
var dist2=Math.abs(pythagoras([objects[i].position[0], objects[i].position[2]] , [this.position[0]+dx, this.position[2]+dy]))
console.log(dist +" ########################### " +dist2)
if ((dist2 < objects[i].min_dist)&(dist > dist2))
{can_move = false; console.log(objects[i].min_dist +" yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy")}
else{console.log(objects[i].min_dist+" can move this is bloody min dist xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx "+dist2);}
}
return can_move;
}
move(event)
{
var key_code = parseInt(event.keyCode)
if (key_code == 37 || key_code == 39 || key_code == 83 || key_code == 87 || key_code == 119|| key_code == 115)
{
var dx = Math.cos(this.angleYaw)*this.moving_speed
var dy = Math.sin(this.angleYaw)*this.moving_speed
console.log("that were moving = dx , dy = "+dx.toString()+" , "+dy.toString())
if ( key_code == 37 || key_code == 87 || key_code == 119) {
if (this.check_min_distance_isnt_overcome_by_this_move(dx, -dy)){
this.position[0] += -dy
this.position[2] += dx
}
}
if (key_code == 39 || key_code == 83 || key_code == 115) {
for (let i = 0; i < this.position.length; i++) {
if (this.check_min_distance_isnt_overcome_by_this_move(dx, dy)){
this.position[0] += dy
this.position[2] += -dx
}
}
}
}
else {
if ( key_code == 38 || key_code == 65 || key_code == 97) {
this.camera_yaw(-this.rotation_speed)
}
if (key_code == 40 || key_code == 68 || key_code == 100) {
this.camera_yaw(this.rotation_speed)
}
this.set_camera_angle()
}
}
}
function translate(pos){
tx,ty,tz=pos
return np.array([
[1,0,0,0],
[0,1,0,0],
[0,0,1,0],
[tx,ty,tz,1]
])}
function rotate_x(angle){
return [
[1,0,0,0],
[0,Math.cos(angle),Math.sin(angle),0],
[0,-Math.sin(angle),Math.cos(angle),0],
[0,0,0,1]
]
}
function rotate_y(a){
return [
[math.cos(a),0, -math.sin(a),0],
[0,1,0,0],
[math.sin(a), 0 , math.cos(a),0],
[0,0,0,1]
]
}
function update_radar(){
var arrow_length = 4;
var object_size = 6.5;
radar_ctx.beginPath();
var mid_screen = [radar.width/2,radar.height/2];
pointing_position = [mid_screen[0]+(player.forward[0]*arrow_length) , mid_screen[1]-(player.forward[2]*arrow_length)]
radar_ctx.moveTo(mid_screen[0], mid_screen[1]); // start of player pos on radar
radar_ctx.lineTo(pointing_position[0], pointing_position[1]);
radar_ctx.lineTo(pointing_position[0]-2, pointing_position[1]-2);
radar_ctx.lineTo(pointing_position[0]+2, pointing_position[1]+2);
radar_ctx.lineTo(pointing_position[0]-2, pointing_position[1]+2);
radar_ctx.moveTo(mid_screen[0], mid_screen[1]);
for (let i = 0; i < objects.length; i++) {
var dx = (player.position[0]-objects[i].position[0])
var dz = player.position[2]+objects[i].position[2]
var x = (dx*2) + mid_screen[0]
var z = (dz*2) + mid_screen[1]
x = x +(object_size/2)
z = z +(object_size/2)
radar_ctx.moveTo(x-object_size,z-object_size);
radar_ctx.lineTo(x+object_size,z+object_size);
radar_ctx.moveTo(x+object_size,z-object_size);
radar_ctx.lineTo(x-object_size,z+object_size);
}
radar_ctx.stroke();
}
function update_matrix_info_debug(matrix_name, matrix){
if (matrix[0].length > 1)
{
for (let x = 1; x < matrix.length+1; x++) {
for (let y = 1; y < matrix.length+1; y++) {
// console.log(matrix_name.toString()+"_"+x.toString()+y.toString());
document.getElementById(matrix_name.toString()+"_"+x.toString()+y.toString()).innerHTML = matrix[x-1][y-1]
}
}
}
else {
for (let x = 1; x < matrix.length+1; x++) {document.getElementById(matrix_name.toString()+"_"+"1"+x.toString()).innerHTML = matrix[x-1]}
}
}
class box{
constructor(x,z,size){
var low_y = 0.5
var high_y = low_y - size
this.position = [x+(size/2),0,z+(size/2)]
this.vertices = [new vertex(x,low_y,z,0),new vertex(x+size,low_y,z,1),new vertex(x,low_y,z+size,2),new vertex(x+size,low_y,z+size,3),
new vertex(x,high_y,z,4),new vertex(x+size,high_y,z,5),new vertex(x,high_y,z+size,6),new vertex(x+size,high_y,z+size,7)
]
this.faces=[ [0,1,3,2,0], [0,1,5,4,0] , [1,3,7,5,1] , [4,5,7,6,4] , [2,6,7,3,2] , [0,4,6,2,0]]
// this.faces=[ [0,4,6,2,0]]
}
draw_all_vertices(){
for (let i = 0; i < this.vertices.length; i++) {
this.vertices[i].screen_projection()
}
}
draw_all_faces(){
var each_point = []
for (let i = 0; i < this.vertices.length; i++) {
each_point.push(this.vertices[i].return_screen_projection())
}
var skip_drawing = if_most_of_these_numbers_are_off_screen(each_point)
if (skip_drawing){console.log(" skipp drawing any faces init ");return;}
ctx.fillStyle = '#f00';
var moved_to_first_yet = false
for (let face = 0; face < this.faces.length; face++) {
ctx.beginPath();
console.log("%%%%%%%%%%%%%%%%%%%%%%%%%");
console.log(this.faces);
console.log(this.faces[face]);
for (let vertex = 0; vertex < this.faces[face].length; vertex++)
{
console.log(vertex+" vertex bef dddddddddddddddddddddddddddddd")
var vertex2 = this.faces[face][vertex]
console.log(vertex2+" vertex aft ddddddddd ")
if (moved_to_first_yet == false)
{
moved_to_first_yet = true
ctx.moveTo( each_point[this.vertices[vertex2].id][0],each_point[this.vertices[vertex2].id][1]);
}
else{ctx.lineTo( each_point[this.vertices[vertex2].id][0],each_point[this.vertices[vertex2].id][1]);}
}
ctx.closePath();
ctx.fill();
}
}
}
class two_d_surdace {
constructor(verex1,verex2,verex3,verex4 , colour){
this.vertices = [verex1,verex2,verex3,verex4]
this.colour = colour
}
draw_all_faces(){
var each_point = []
for (let i = 0; i < this.vertices.length; i++) {
each_point.push(this.vertices[i].return_screen_projection(true))
}
ctx.fillStyle = this.colour;
var moved_to_first_yet = false
for (let vertex = 0; vertex < this.vertices.length; vertex++)
{
console.log(each_point[vertex][0]+" , "+each_point[vertex][1]+ " actual x y points on screen for this vertex of corner of floor ")
if (moved_to_first_yet == false)
{
moved_to_first_yet = true
ctx.moveTo( each_point[vertex][0],each_point[vertex][1]);
}
else{ctx.lineTo( each_point[vertex][0],each_point[vertex][1]);}
}
ctx.closePath();
ctx.fill();
}
}
function if_off_screen(x, y)
{
if (x> canvas.width || x < 0){console.log(x +" x = off screen "); return true;}
if (y > canvas.height || y < 0){console.log(y +" y = off screen "); return true;}
console.log(x +" , "+y + " =x,y = not off screen ");
return false;
}
function if_most_of_these_numbers_are_off_screen(numbers){
var threshold = 1; //Math.floor(numbers.length*0.49)
var counter = 0
console.log(numbers + " xxxx numbers as they come in ")
for (let i = 0; i < numbers.length; i++) { if (if_off_screen(numbers[i][0], numbers[i][1])){console.log(numbers[i]+" , "+numbers[i+1]+ " = numbers[i] are off screen"); counter +=1} else{console.log(numbers[i]+" , "+numbers[i+1]+ " = numbers[i] not off screen")} }
console.log("quuin quoirs of raptor");
if (counter >= threshold){console.log(threshold+" < " + counter);return true}
console.log(threshold+" > " + counter);
return false;
}
player = new player();
projection = new Projection()
objects = [] //
floor = new two_d_surdace(new vertex(50,floor_y_pos,50) , new vertex(-50,floor_y_pos,50) , new vertex(-50,floor_y_pos,-50) , new vertex(50,floor_y_pos,-50) , '#F90' )
update_radar()
$(document).on("keypress", function (event) {
player.move(event)
ctx.beginPath();
radar_ctx.beginPath();
radar_ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.clearRect(0, 0, canvas.width, canvas.height);
for (let i = 0; i < objects.length; i++) {
objects[i].draw_all_faces()
objects[i].draw_all_vertices()
}
floor.draw_all_faces()
update_radar()
});
</script>
</body>
So I am using this npm package: node-stl
And its working great. However the regexp syntax, mathematics and geometrical calculations are somewhat confusing to me. Especially all at the same time.
Basically what I want to achieve is to extend the script to calculate the bounding box of the STL.
Here is the main file that calculates the volume and weight of the STL being parsed/read.
var fs = require('fs');
// Vertex
function Vertex (v1,v2,v3) {
this.v1 = Number(v1);
this.v2 = Number(v2);
this.v3 = Number(v3);
}
// Vertex Holder
function VertexHolder (vertex1,vertex2,vertex3) {
this.vert1 = vertex1;
this.vert2 = vertex2;
this.vert3 = vertex3;
}
// transforming a Node.js Buffer into a V8 array buffer
function _toArrayBuffer (buffer) {
var
ab = new ArrayBuffer(buffer.length),
view = new Uint8Array(ab);
for (var i = 0; i < buffer.length; ++i) {
view[i] = buffer[i];
}
return ab;
}
// calculation of the triangle volume
// source: http://stackoverflow.com/questions/6518404/how-do-i-calculate-the-volume-of-an-object-stored-in-stl-files
function _triangleVolume (vertexHolder) {
var
v321 = Number(vertexHolder.vert3.v1 * vertexHolder.vert2.v2 * vertexHolder.vert1.v3),
v231 = Number(vertexHolder.vert2.v1 * vertexHolder.vert3.v2 * vertexHolder.vert1.v3),
v312 = Number(vertexHolder.vert3.v1 * vertexHolder.vert1.v2 * vertexHolder.vert2.v3),
v132 = Number(vertexHolder.vert1.v1 * vertexHolder.vert3.v2 * vertexHolder.vert2.v3),
v213 = Number(vertexHolder.vert2.v1 * vertexHolder.vert1.v2 * vertexHolder.vert3.v3),
v123 = Number(vertexHolder.vert1.v1 * vertexHolder.vert2.v2 * vertexHolder.vert3.v3);
return Number(1.0/6.0)*(-v321 + v231 + v312 - v132 - v213 + v123);
}
// parsing an STL ASCII string
function _parseSTLString (stl) {
var totalVol = 0;
// yes, this is the regular expression, matching the vertexes
// it was kind of tricky but it is fast and does the job
var vertexes = stl.match(/facet\s+normal\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+outer\s+loop\s+vertex\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+vertex\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+vertex\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+endloop\s+endfacet/g);
vertexes.forEach(function (vert) {
var preVertexHolder = new VertexHolder();
vert.match(/vertex\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s+([-+]?\b(?:[0-9]*\.)?[0-9]+(?:[eE][-+]?[0-9]+)?\b)\s/g).forEach(function (vertex, i) {
var tempVertex = vertex.replace('vertex', '').match(/[-+]?[0-9]*\.?[0-9]+/g);
var preVertex = new Vertex(tempVertex[0],tempVertex[1],tempVertex[2]);
preVertexHolder['vert'+(i+1)] = preVertex;
});
var partVolume = _triangleVolume(preVertexHolder);
totalVol += Number(partVolume);
})
var volumeTotal = Math.abs(totalVol)/1000;
return {
volume: volumeTotal, // cubic cm
weight: volumeTotal * 1.04 // gm
}
}
// parsing an STL Binary File
// (borrowed some code from here: https://github.com/mrdoob/three.js/blob/master/examples/js/loaders/STLLoader.js)
function _parseSTLBinary (buf) {
buf = _toArrayBuffer(buf);
var
headerLength = 80,
dataOffset = 84,
faceLength = 12*4 + 2,
le = true; // is little-endian
var
dvTriangleCount = new DataView(buf, headerLength, 4),
numTriangles = dvTriangleCount.getUint32(0, le),
totalVol = 0;
for (var i = 0; i < numTriangles; i++) {
var
dv = new DataView(buf, dataOffset + i*faceLength, faceLength),
normal = new Vertex(dv.getFloat32(0, le), dv.getFloat32(4, le), dv.getFloat32(8, le)),
vertHolder = new VertexHolder();
for(var v = 3; v < 12; v+=3) {
var vert = new Vertex(dv.getFloat32(v*4, le), dv.getFloat32((v+1)*4, le), dv.getFloat32( (v+2)*4, le ) );
vertHolder['vert'+(v/3)] = vert;
}
totalVol += _triangleVolume(vertHolder);
}
var volumeTotal = Math.abs(totalVol)/1000;
return {
volume: volumeTotal, // cubic cm
weight: volumeTotal * 1.04 // gm
}
}
// NodeStl
// =======
// > var stl = NodeStl(__dirname + '/myCool.stl');
// > console.log(stl.volume + 'cm^3');
// > console.log(stl.weight + 'gm');
function NodeStl (stlPath) {
var
buf = fs.readFileSync(stlPath),
isAscii = true;
for (var i=0, len=buf.length; i<len; i++) {
if (buf[i] > 127) { isAscii=false; break; }
}
if (isAscii)
return _parseSTLString(buf.toString());
else
return _parseSTLBinary(buf);
}
module.exports = NodeStl;
If anyone could help me with this it would be great. I know and it feels like it simple. That I just need to know max/min of the different directions(x,y,z) and could then calculate the bounding box.
But I do not understand what the max/min for x,y and z is here. Please answer if you have an idea.
I've made a new branch https://github.com/johannesboyne/node-stl/tree/boundingbox could you please verify whether the applied algorithm works?
Best,
Johannes
Edit: If the branch is stable -> works I'll push it into v.0.1.0 (don't know why it is still 0.0.1)
I have an SVG image from which I'd like to extract several rectangular regions as independent SVG images. Because the original image is rather large but the elements intersecting the areas of interest are small, I do not want elements which lie entirely outside the cropped viewBox to remain in the cropped SVG image.
Conceptually, what I'm looking for is this:
The cropped SVG (yes, the output must be SVG, not a bitmap) should not contain elements for the spiral or the star, as they fall entirely outside the area of interest. (Yes, the nonintersecting elements really must be removed, due to the source SVG being several orders of magnitude more bytes than the cropped SVG, as I intend to crop the source in different ways hundreds of times.) I want to be able to specify the area of interest on the command-line, as well, due to having quite a number of such cropped images to produce.
Are there any tools which can do this?
SVG elements can be parsed and flagged true/false as inside a svg rect object and/or intersecting the rect object.
Would this work for you?
isEnclosed = mySVG.checkEnclosure(myElement, RectObj)
doesIntersect = mySVG.checkIntersection(myElement, RectObj)
I use the Jordan Curve Theorem to test for points inside an svg polygon. Your polygon would be your viewBox. Posssibly this could work for you if each element has a target point associated with it(i.e. center point) to determine if you want to show it or not.
The following is the javascript I use:(caution: I think the polygon should have counter-clockwise points. Always a good idea when dealing with polygons)
//---Point-in-polygon: Jordan Curve Theorem---
function pointInPolygon(myPolygon,px,py)
{
var pointsList=myPolygon.points
var x
var y
var x1
var y1
var crossings=0
var verts=pointsList.numberOfItems
//---Iterate through each line ---
for ( var i = 0; i < verts; i++ )
{
var vertx=pointsList.getItem(i).x
var verty=pointsList.getItem(i).y
if(i<verts-1)
{
var vertxNext=pointsList.getItem(i+1).x
var vertyNext=pointsList.getItem(i+1).y
}
else
{
var vertxNext=pointsList.getItem(0).x
var vertyNext=pointsList.getItem(0).y
}
/* This is done to ensure that we get the same result when
the line goes from left to right and right to left */
if ( vertx < vertxNext){
x1 = vertx;
x2 = vertxNext;
} else {
x1 = vertxNext;
x2 = vertx;
}
/* First check if the ray is possible to cross the line */
if ( px > x1 && px <= x2 && ( py < verty || py <= vertyNext ) ) {
var eps = 0.000000001;
/* Calculate the equation of the line */
var dx = vertxNext - vertx;
var dy = vertyNext - verty;
var k;
if ( Math.abs(dx) < eps ){
k = Infinity;
} else {
k = dy/dx;
}
var m = verty - k * vertx;
/* Find if the ray crosses the line */
y2 = k * px + m;
if ( py <= y2 ){
crossings++;
}
}
}
//---odd number of crossings: point inside polygon--
var crossFlag=(crossings/2)+""
if(crossFlag.indexOf(".")!=-1)
return true;
else
return false;
}
Since your svg elements are transformed, you may need to convert them to screen points. I've used the following javascript for the various svg elements(line, rect, circle, ellipse, polygon, polyline, and path)
//----build a generic document SVG root to hold svg point---
function screenLine(line,svg)
{
var sCTM = line.getCTM()
var x1=parseFloat(line.getAttribute("x1"))
var y1=parseFloat(line.getAttribute("y1"))
var x2=parseFloat(line.getAttribute("x2"))
var y2=parseFloat(line.getAttribute("y2"))
var mySVGPoint1 = svg.createSVGPoint();
mySVGPoint1.x = x1
mySVGPoint1.y = y1
mySVGPointTrans1 = mySVGPoint1.matrixTransform(sCTM)
line.setAttribute("x1",mySVGPointTrans1.x)
line.setAttribute("y1",mySVGPointTrans1.y)
var mySVGPoint2 = svg.createSVGPoint();
mySVGPoint2.x = x2
mySVGPoint2.y = y2
mySVGPointTrans2= mySVGPoint2.matrixTransform(sCTM)
line.setAttribute("x2",mySVGPointTrans2.x)
line.setAttribute("y2",mySVGPointTrans2.y)
//---force removal of transform--
line.setAttribute("transform","")
line.removeAttribute("transform")
}
function screenCircle(circle,svg)
{
var sCTM = circle.getCTM()
var scaleX = sCTM.a;
var cx=parseFloat(circle.getAttribute("cx"))
var cy=parseFloat(circle.getAttribute("cy"))
var r=parseFloat(circle.getAttribute("r"))
var mySVGPointC = svg.createSVGPoint();
mySVGPointC.x = cx
mySVGPointC.y = cy
mySVGPointTransC = mySVGPointC.matrixTransform(sCTM)
circle.setAttribute("cx",mySVGPointTransC.x)
circle.setAttribute("cy",mySVGPointTransC.y)
circle.setAttribute("r",r*scaleX)
//---force removal of transform--
circle.setAttribute("transform","")
circle.removeAttribute("transform")
}
function screenEllipse(ellipse,svg)
{
var sCTM = ellipse.getCTM()
var scaleX = sCTM.a;
var scaleY = sCTM.d;
var cx=parseFloat(ellipse.getAttribute("cx"))
var cy=parseFloat(ellipse.getAttribute("cy"))
var rx=parseFloat(ellipse.getAttribute("rx"))
var ry=parseFloat(ellipse.getAttribute("ry"))
var mySVGPointC = svg.createSVGPoint();
mySVGPointC.x = cx
mySVGPointC.y = cy
mySVGPointTransC = mySVGPointC.matrixTransform(sCTM)
ellipse.setAttribute("cx",mySVGPointTransC.x)
ellipse.setAttribute("cy",mySVGPointTransC.y)
ellipse.setAttribute("rx",rx*scaleX)
ellipse.setAttribute("ry",ry*scaleY)
//---force removal of transform--
ellipse.setAttribute("transform","")
ellipse.removeAttribute("transform")
}
function screenRect(rect,svg)
{
var sCTM = rect.getCTM()
var scaleX = sCTM.a;
var scaleY = sCTM.d;
var x=parseFloat(rect.getAttribute("x"))
var y=parseFloat(rect.getAttribute("y"))
var width=parseFloat(rect.getAttribute("width"))
var height=parseFloat(rect.getAttribute("height"))
var mySVGPoint = svg.createSVGPoint();
mySVGPoint.x = x
mySVGPoint.y = y
mySVGPointTrans = mySVGPoint.matrixTransform(sCTM)
rect.setAttribute("x",mySVGPointTrans.x)
rect.setAttribute("y",mySVGPointTrans.y)
rect.setAttribute("width",width*scaleX)
rect.setAttribute("height",height*scaleY)
//---force removal of transform--
rect.setAttribute("transform","")
rect.removeAttribute("transform")
}
function screenPolyline(myPoly,svg)
{
var sCTM = myPoly.getCTM()
var pointsList = myPoly.points;
var n = pointsList.numberOfItems;
for(var m=0;m<n;m++)
{
var mySVGPoint = mySVG.createSVGPoint();
mySVGPoint.x = pointsList.getItem(m).x
mySVGPoint.y = pointsList.getItem(m).y
mySVGPointTrans = mySVGPoint.matrixTransform(sCTM)
pointsList.getItem(m).x=mySVGPointTrans.x
pointsList.getItem(m).y=mySVGPointTrans.y
}
//---force removal of transform--
myPoly.setAttribute("transform","")
myPoly.removeAttribute("transform")
}
function screenPath(path,svg)
{
var sCTM = path.getCTM()
var scaleX = sCTM.a;
var scaleY = sCTM.d;
var segList=path.pathSegList
var segs=segList.numberOfItems
//---change segObj values
for(var k=0;k<segs;k++)
{
var segObj=segList.getItem(k)
if(segObj.x && segObj.y )
{
var mySVGPoint = svg.createSVGPoint();
mySVGPoint.x = segObj.x
mySVGPoint.y = segObj.y
mySVGPointTrans = mySVGPoint.matrixTransform(sCTM)
segObj.x=mySVGPointTrans.x
segObj.y=mySVGPointTrans.y
}
if(segObj.x1 && segObj.y1)
{
var mySVGPoint1 = svg.createSVGPoint();
mySVGPoint1.x = segObj.x1
mySVGPoint1.y = segObj.y1
mySVGPointTrans1 = mySVGPoint1.matrixTransform(sCTM)
segObj.x1=mySVGPointTrans1.x
segObj.y1=mySVGPointTrans1.y
}
if(segObj.x2 && segObj.y2)
{
var mySVGPoint2 = svg.createSVGPoint();
mySVGPoint2.x = segObj.x2
mySVGPoint2.y = segObj.y2
mySVGPointTrans2 = mySVGPoint2.matrixTransform(sCTM)
segObj.x2=mySVGPointTrans2.x
segObj.y2=mySVGPointTrans2.y
}
if(segObj.r1)segObj.r1=segObj.r1*scaleX
if(segObj.r2)segObj.r2=segObj.r2*scaleX
}
//---force removal of transform--
path.setAttribute("transform","")
path.removeAttribute("transform")
}
//---changes all transformed points to screen points---
function screenPolygon(myPoly,mySVG)
{
var sCTM = myPoly.getCTM()
var pointsList = myPoly.points;
var n = pointsList.numberOfItems;
for(var m=0;m<n;m++)
{
var mySVGPoint = mySVG.createSVGPoint();
mySVGPoint.x = pointsList.getItem(m).x
mySVGPoint.y = pointsList.getItem(m).y
mySVGPointTrans = mySVGPoint.matrixTransform(sCTM)
pointsList.getItem(m).x=mySVGPointTrans.x
pointsList.getItem(m).y=mySVGPointTrans.y
}
//---force removal of transform--
myPoly.setAttribute("transform","")
myPoly.removeAttribute("transform")
}