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// requires matrix_vector_lib.js
// TODO we could make some libraryless way of checking dependencies and versions.
// global namespace object
var WireframeModel;
(function(){
// converts a point from three space to the canvas plane.
// Note: because of depth perspective, this conversion is not
// easy to define if the point lies behind the camera.
// There are two options:
// When drawing a line, another colinear point in front of the camera may be provided
// to help find an alternate point.
// if both points lie behind the camera or the colinear_point is not provided,
// this function will return null.
function project(canvas, xyz, view, colinear_point){
if(!xyz) return null; // point has been deleted or does not exist
var view_transform = view.transform;
var origin = view.origin;
var zoom_scale = view.zoom_scale;
var zoom_dist = view.zoom_dist;
if(!zoom_scale) zoom_scale = 1;
if(!zoom_dist) zoom_dist = 0;
if(!origin) origin = [0,0,0];
var w = canvas.width;
var h = canvas.height;
var scale = Math.min(w, h);
var v = xyz.slice(0);
if(origin) v = vector_minus(v, origin, v);
var z = vector_dot(view_transform[2], v);
if(z <= -zoom_dist){ // this point is on the wrong side of the viewer, find the closest point on the correct side if we can.
if(!colinear_point) return null;
var v2 = colinear_point.slice(0);
if(origin) vector_minus(v2, origin, v2);
var z2 = vector_dot(view_transform[2], v2);
if(z2 < 0) return null;
// get the coefficients for a complex combination.
// t*z + (1-t)*z2 = 0.0002 -- z of new point is just barely infront of the camera.
var t = (0.0002 - z2)/(z - z2); // no division by zero, z is negative, z2 is positive
vector_add(vector_scale(v, t, v),
vector_scale(v2, 1-t, v2),
v);
z = vector_dot(view_transform[2], v); }
var scale2 = zoom_scale * scale / (zoom_dist + z);
return [ scale2 * vector_dot(view_transform[0], v) + 0.5 * w,
scale2 * vector_dot(view_transform[1], v) + 0.5 * h ]; }
// Just like the project function above but for a set of points.
// It's put into a loop a little better.
function project_all(canvas, points, point_projections, view){
var view_transform = view.transform;
var origin = view.origin;
var zoom_scale = view.zoom_scale;
var zoom_dist = view.zoom_dist;
if(!zoom_scale) zoom_scale = 1;
if(!zoom_dist) zoom_dist = 0;
if(!origin) origin = [0,0,0];
if(!point_projections) point_projections = [];
point_projections.length = points.length;
var w = canvas.width;
var h = canvas.height;
var w_2 = w/2;
var h_2 = h/2;
var scale = zoom_scale * Math.min(w, h);
var v00 = view_transform[0][0];
var v01 = view_transform[0][1];
var v02 = view_transform[0][2];
var v10 = view_transform[1][0];
var v11 = view_transform[1][1];
var v12 = view_transform[1][2];
var v20 = view_transform[2][0];
var v21 = view_transform[2][1];
var v22 = view_transform[2][2];
for(var i = 0; i < points.length; ++i){
var pt = points[i];
var x = pt[0];
var y = pt[1];
var z = pt[2];
if(origin){
x -= origin[0];
y -= origin[1];
z -= origin[2]; }
var depth = x*v20 + y*v21 + z*v22;
var scale2 = scale / (zoom_dist + depth);
if(!point_projections[i]) point_projections[i] = [0, 0];
var point_projection = point_projections[i];
point_projection[0] = scale2 * (x*v00 + y*v01 + z*v02) + w_2;
point_projection[1] = scale2 * (x*v10 + y*v11 + z*v22) + h_2; }
return point_projections; }
// A wireframe model and all the controls needed to move the camera and draw.
// despite the name, it may also include polygon surfaces.
function __WireframeModel(){
var WFMObj = this;
var view_origin = [0, 0, 0];
var view_transform = [[1, 0, 0],
[0, 1, 0],
[0, 0, 1]];
var points = []; //global
var point_projections = [];
var solo_points = {};
//var solo_points = {};
var lines = [];
var zoom_scale = 1;
var zoom_dist = 1;
// just because these actual objects is returned
// doesn't mean you should modify it externally if you can help it.
WFMObj.getPoints = function getPoints(){
return points; }
WFMObj.getPoint = function getPoint(index){
return points[index].slice(0); }
WFMObj.getLines = function getLines(){
return lines; }
WFMObj.getLine = function getLine(index){
return lines[index].slice(0); }
WFMObj.getViewTransform = function getViewTransform(){
return view_transform; }
WFMObj.addPoint = function addPoint(pt){
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throw "pt ref at index " + i + " of line was not an integer: " + ptindex; }
if(ptindex < 0 || ptindex >= points.length){
throw "pt ref at index " + i + " of line was not in bounds: " + ptindex; }}
lines.push(line);
return lines.length - 1; }
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if(cameracentric) offset = matrix_mult(view_transform, [offset])[0];
//alert("offset: " + offset);
vector_add(origin, offset, origin); }
// converts a point from three space to the canvas plane.
// Note: because of depth perspective, this conversion is not
// easy to define if the point lies behind the camera.
// There are two options:
// When drawing a line, another colinear point in front of the camera may be provided
// to help find an alertnate point.
// if both points lie behind the camera or the colinear_point is not provided,
// this function will return null.
function project(canvas, xyz, view_transform, origin, colinear_point){
if(!xyz) return null; // point has been deleted or does not exist
var w = canvas.width;
var h = canvas.height;
var scale = Math.min(w, h);
var v = xyz.slice(0);
if(origin) v = vector_minus(v, origin, v);
var z = vector_dot(view_transform[2], v);
if(z <= -zoom_dist){
if(!colinear_point) return null;
var v2 = colinear_point.slice(0);
if(origin) vector_minus(v2, origin, v2);
var z2 = vector_dot(view_transform[2], v2);
if(z2 < 0) return null;
// get the coefficients for a complex combination.
// t*z + (1-t)*z2 = 0.0002 -- z of new point is just barely infront of the camera.
var t = (0.0002 - z2)/(z - z2); // no division by zero, z is negative, z2 is positive
vector_add(vector_scale(v, t, v),
vector_scale(v2, 1-t, v2),
v);
z = vector_dot(view_transform[2], v); }
var scale2 = zoom_scale * scale / (zoom_dist + z);
return [ scale2 * vector_dot(view_transform[0], v) + 0.5 * w,
scale2 * vector_dot(view_transform[1], v) + 0.5 * h ]; }
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