three.js - canvas texture on tube geometry for ipad - javascript

I've a 3d model of a tube geometry. There are 18000 co-ordinates on production side. I am taking every 9th co-ordinate so that actually plotting 9000 co-ordinates to build a tube geometry. I've to use CanvasRenderer only.
Now when I use vertexColors: THREE.VertexColors in WebGLRenderer, the model displays different color on each face. When I change it to CanvasRenderer, the model turns into white color only. Even I change vertexColors: THREE.FaceColors, the result is same.
Please find below the link of jsfiddle and link of my previous where mrdoob added support for material.vertexColors = THREE.FaceColors to CanvasRenderer.
support for vertex color in canvas rendering
tube in canvas rendering
Please find below the image to apply colors based on values.
As shown in the image there are 12 values at 12 different degrees for every co-ordinate. So I've created a tube with radius segment of 12. Then I've stored these values into JSON file but as there 18000 points, the file becomes to heavy. Even though I am plotting 2000 points it takes too much time. For 2000 segments and each segment has 12 faces, there are 24000 faces on a tube.
Please find below the programming logic to apply color based on value of a parameter.
// get res values & apply color
var lblSeg=0; var pntId; var d=0; var faceLength=tube.faces.length;
var degrees = [ '30', '60', '90', '120', '150', '180', '210', '240', '270', '300', '330' ];
var faces = tube.faces; var degreeCntr=0; var degreeProp;
//console.log(faces);
var res30=0,res60=0,res90=0,res120=0,res150=0,res180=0,res210=0,res240=0,res270=0,res300=0,res330=0;
var res; var resDegree; var pnt=0;
// fetching json data of resistivity values at different degree as //shown in the image
var result = getResValue();
for(var k=0; k<faceLength; k++){
resDegree = degrees[degreeCntr];
degreeProp = "r"+resDegree;
res = result.resistivity[pnt][degreeProp];
objects.push(result.resistivity[pnt]);
f = faces[k];
color = new THREE.Color( 0xffffff );
if(res<5){
color.setRGB( 197/255, 217/255, 241/255);
}
else if(res>=5 && res<50){
color.setRGB( 141/255, 180/255, 226/255);
}
else if(res>=50 && res<100){
color.setRGB( 83/255, 141/255, 213/255);
}
else if(res>=100 && res<200){
color.setRGB( 22, 54, 92);
}
else if(res>=200 && res<300){
color.setRGB( 15/255,36/255,62/255);
}
else if(res>=300 && res<400){
color.setRGB( 220/255, 230/255, 241/255);
}
else if(res>=400 && res<700){
color.setRGB( 184/255, 204/255, 228/255);
}
else if(res>=700 && res<1200){
color.setRGB( 149/255, 179/255, 215/255);
}
else if(res>=1200 && res<1500){
color.setRGB( 54/255, 96/255, 146/255);
}
else if(res>=1700 && res<1800){
color.setRGB( 36/255, 84/255, 98/255);
}
else if(res>1900){
color.setRGB( 128/255, 128/255, 128/255);
}
for(var j=0;j<4;j++)
{
tube.vertices.push(f.centroid);
vertexIndex = f[ faceIndices[ j ] ];
p = tube.vertices[ vertexIndex ];
f.vertexColors[ j ] = color;
}
degreeCntr++;
if(degreeCntr==10){
degreeCntr=0;
}
if(k%12==0 && k!=0){
pnt++;
}
}
This logic takes too much time to render the model and the model becomes too heavy and we can't perform other operations. The FPS on android drops at 2-3 FPS. Actually I've to render this model on iPad so have to use canvas renderer only.
So, how do I make this model lighter to load and works smoothly on iPad ? and is there any other way to apply colors on every face ? If canvas map as texture can be applied to make the model lighter, how do I build that map with all the colors based on value ?
Update:
After changing library version to r53, vertexColors: THREE.FaceColors and face.color.setRGB( Math.random(), Math.random(), Math.random()), the model displays random color for each face on canvas rendering.
So now the issue is applying colors as per requirements (either by canvas map or any feasible solution) and to make the model lighter to load it smoothly on iPad.

I believe this will give you a little bit better performance + if you could come up with some automated method of calculating colors for each angle offset, that you could set hex color directly:
for ( var i = 0; i < tube.faces.length; i ++ ) {
tube.faces[ i ].color.setHex( Math.random() * 0xffffff );
}
As I explained to you in the previous message - three.js - text next to line, using canvas textures will only increase load to you fps if you'll attempt to render so many faces.
If you really want to render 24,000 faces on canvas renderer and still hope that it gonna show up good on an iPad – you are out of your mind!))
Here is the only solution that I can think of for now:
1) Set your tube to only 1 segment.
2) Create 12 canvas elements (for every radius segment) with Width equal to your tube length (see my link above).
3) Now imagine that your 2000 segments you are going to create inside of each canvas. So, you divide your canvas length by 2000 and for every one of the portion of this division you set your calculated color!!! (Just like the Stats() FPS bar shows it’s bar, but you are going to have each bar different color).
4) Then you just apply your colored-bars-canvas-texture to each one of your 12 radius segments and you are good to go!!
This way you’ll only get initial page load (calculating 'em 24,000 colored-bars) and YOUR WHOLE TUBE ONLY GONNA BE 12 FACES!!!
Now, I know your next question is going to be: How I'll pick my faces to show my lines with tag text?
Well, very simple! Just take current face (1 of 12) pick position coordinates and translate them back to your JSON, just the same way you would do with 24,000 faces;)
Hope that helps!

Related

Drawing faces over a country without overlapping borders in Three.js

My problem is that when creating faces for a country, there are faces which overlap the border.
Below is the image when all coordinates are used when creating the faces
image with all values (coordinates)
values_axis1 contains all the X coordinates [63.0613691022453, 65.1611029239906, 66.0721609548093, 68.8109022381195, 71.1822098033678..]
values_axis2 contains all the Y coordinates [34.37065245791981, 35.30003249470688, 38.11207931425505, 38.228254752215044..]
values_axis3 contains all the Z coordinates
for (var i = 0; i < values_axis1.length; i ++) {
object_geometry.vertices.push(new THREE.Vector3(values_axis1[i], values_axis2[i], values_axis3[i]));
object_geometry.faces.push(new THREE.Face3(0, i + 1, i));
}
Buy changing i++ to i+=2 we get this image of skipping some values
Arrow obviously shows the point zero where all triangles are drawn from.
Below is the part of code for that.
object_geometry.faces.push(new THREE.Face3(DRAW_FROM_HERE, i + 1, i));
This isn't per say a programming problem but more like a 'is there a algorithm for this'.
I could check for faces that collide with a border from point zero and skip them but then there would be holes and that would need to be filled by drawing from some other location. That could be done manually but doing that for all the countries in the world would take ages. I'm sure this could be done by somehow calculating where the holes are but I have no idea how that would be done.
If someone comes up even with a really bad solution performance wise it would be great! I'm planning on putting all the results in a file which could then be loaded and drawn since there is really no need to do this processing every time since the borders never move.
EDIT: ShapeGeometry was suggested and has been tested. I was wrong when I said that Z coordinates are not relevant but obviously they are due to the curvature of the globe.
Image of the shapeGeometry. 2d but otherwise perfect.
Question edited.
Edit: Solution
Thanks to #Gilles-Philippe Paillé for suggesting ear clipping. Found a great library https://github.com/mapbox/earcut
Here is updated code for others who might have the same issue.
function createVertexForEachPoint(object_geometry, values_axis1, values_axis2,
values_axis3) {
var values_x_y = []; // add x and y values to the same list [x,y,x,y,x,y..]
for (var i = 0; i < values_axis1.length; i++) {
values_x_y.push(values_axis1[i], values_axis2[i]);
}
// https://github.com/mapbox/earcut
var triangles = earcut(values_x_y);
// triangles = [37, 36, 35, 35, 34, 33, 32, 31, 30, 30, …] [a,b,c,a,b,c,a,b,c..]
// triangles contain only the verticies that are needed
// previously all possible faces were added which resulted in overlapping borders
// add all points, in this case coordinates. Same as before
for (var i = 0; i < values_axis1.length; i++) {
object_geometry.vertices.push(new THREE.Vector3(values_axis1[i], values_axis2[i], values_axis3[i]));
}
// go through the list and pick the corners (a,b,c) of the triangles and add them to faces
for (var i = 0; i < triangles.length; i += 3) {
var point_1 = triangles[i];
var point_2 = triangles[i+1];
var point_3 = triangles[i+2];
object_geometry.faces.push(new THREE.Face3(point_1, point_2, point_3));
}
}
I use a geoJSON which has 'polygon' and 'multipolygon' shapes. This code works for polygons atm but shouldn't need too much tweaking to work with multipolygons since the library supports also holes earcut(vertices[, holes, dimensions = 2]).
image of the result

(Three.JS) Transform controls for translation (Size Issue)

I am working on customizing the transform controls available in three.js for my project.
I have already changed the rotation part and now working on translation part.
if you notice in translation Gizmo, there is a XYZ octahedron in the center. I have removed all other planes and arrows and wrote all functionality only on that center mesh, which is working fine.
Now I am only stuck at one small problem, that is the size and position of that controller. I changed that Octahedron to boxGeometry and writing the code to make the size of that controller to be exact size of the selected object. for that I get the idea to make the size of the controller, same as the boxHelper size, which act as outline of object.
when I tried this logic in sample code, where I created a box, and getting the size of box helper and creating another box of same size, it was working fine. but when I am writing same code in threejs transform controls, result is not the same.
below is the geometry code init
XYZ: [[ new THREE.Mesh( new THREE.BoxGeometry( 0.1, 0.1, 0.1 ), pickerMaterial )]],
then I am getting the size of box3 when attaching to any object
this.addBoxHelper = function () {
this.removeBoxHelper();
if(this.object.box3) {
**this.object.box3.getSize(selectionBoxSize);**
console.log(selectionBoxSize)
this.objectBoxHelper = new THREE.Box3Helper(this.object.box3, 0xffff00);
this.objectBoxHelper.canSelect = function () {
return false;
}
this.object.add(this.objectBoxHelper);
}
}
then below is my update function of transform controls
this.update = function () {
if ( scope.object === undefined ) return;
scope.object.updateMatrixWorld();
worldPosition.setFromMatrixPosition( scope.object.matrixWorld );
worldRotation.setFromRotationMatrix( tempMatrix.extractRotation( scope.object.matrixWorld ) );
scope.object.box3.getSize(selectionBoxSize);
scope.object.getWorldPosition(selectionBoxPos);
camera.updateMatrixWorld();
camPosition.setFromMatrixPosition( camera.matrixWorld );
camRotation.setFromRotationMatrix( tempMatrix.extractRotation( camera.matrixWorld ) );
**scaleT = selectionBoxSize;**
//below three lines are for dynamic size change based on camera position..for
//next level functionality
//scaleT.x = worldPosition.distanceTo( camPosition ) / 6 * selectionBoxSize.x;
//scaleT.y = worldPosition.distanceTo( camPosition ) / 6 * selectionBoxSize.y;
//scaleT.z = worldPosition.distanceTo( camPosition ) / 6 * selectionBoxSize.z;
this.position.copy( selectionBoxPos );
this.scale.set( scaleT.x, scaleT.y, scaleT.z);
this.updateMatrixWorld();
below is the output of console log
TransformControls.js:526 Vector3 {x: 10.020332336425781, y: 2.621583938598633, z: 3.503500819206238}
TransformControls.js:601 Vector3 {x: 10.020332336425781, y: 2.621583938598633, z: 3.503500819206238}
as you can see, the scale is the same, but the result is different. see the result in below images.
as you see in images, that red color box at bottom is translation controller but smaller than selection box.
another issue is that pivot of my objects are at bottom, and I want this controller to come at the center of the selection box, that is also not happening with getCenter method of box3.
Please help!! let me know if I am unclear in explaining the issue
If you are getting the bounding box of the object from its geometry, that will be wrong because it doesn't take the objects transform into account. You have to use box3.setFromObject (yourObject) instead. does that help?

Repair normals on possibly bad .stl files

I am new to Three.js and have been assigned the task of trying to repair the normals on files that have been coming in occasionally that appear to be bad. We do not know if they are bad scans or possibly bad uploads. We are looking into the upload function, but also would like to try and repair them if possible. Can anyone provide any ideas or tips to repair the file or find the correct normals?
Below is the code where we grab the normals and how we grab them. NOTE: this code works fine generally, it is only a problem when the normals are bad. I am also attaching one of the files so you can see the types of normals and "bad file" I am dealing with. Get File here
We are also using VTK on the backend with C++, so a solution or idea using either of these is helpful.
my.geometry = geometry;
var front = new THREE.MeshPhongMaterial(
{color: 0xe2e4dc, shininess: 50, side: THREE.DoubleSide});
var mesh = [new THREE.Mesh(geometry, front)];
my.scene.add(mesh[0]);
my.objects.push(mesh[0]);
var rc = new THREE.Raycaster();
var modelData = {'objects': [mesh[0].id], 'id': mesh[0].id};
var normalFound = false;
for (var dy = 80; dy >= -80; dy = dy - 10) {
console.log('finding a normal on', 0, dy, -200);
rc.set(new THREE.Vector3(0, dy, -200), new THREE.Vector3(0, 0, 1));
var hit = rc.intersectObjects([mesh[0]]);
if (hit.length) {
my.normal = hit[0].face.normal.normalize();
console.log('normal', my.normal.z);
modelData['normal'] = my.normal;
if ((my.normal.z > 0.9 && my.normal.z < 1.1)) {
my.requireOrienteering = true;
modelData['arch'] = 'lower';
normalFound = true;
console.log('we have a lower arch');
} else if ((my.normal.z < -0.9 && my.normal.z > -1.1)) {
modelData['arch'] = 'upper';
normalFound = true;
console.log('we have an upper arch');
}
break;
}
}
Calculating the normals is an easy step. If you calculate the cross product of two vectors (geometrical one), you will get a vector, that is orthogonal to the two, you input. All you have to do now is normalize it, since normals should be normalised to not mess up lightning calculations.
For smooth surfaces, you have to calculate all normals on the point and average them. For flat surfaces each vertex has multiple normales (one for each surface).
In pseudo code it will look like this for quads:
foreach quad : mesh
foreach vertex : quad
vector1 = neighborVertex.pos - vertex.pos;
vector2 = otherNeighborVertex.pos - vertex.pos;
vertex.normal = normalize(cross(vector1, vector2));
end foreach;
end foreach;
VTK has a filter named vtkPolyDataNormals that you can run on your file to compute normals. You probably want to call ConsistencyOn(), NonManifoldTraversalOn(), and AutoOrientNormalsOn() before running it.
If you want point-normals (instead of per-cell normals) and your shape has sharp corners, you probably want to provide a feature angle with SetFeatureAngle() and call SplittingOn().

mouse position to isometric tile including height

Struggeling translating the position of the mouse to the location of the tiles in my grid. When it's all flat, the math looks like this:
this.position.x = Math.floor(((pos.y - 240) / 24) + ((pos.x - 320) / 48));
this.position.y = Math.floor(((pos.y - 240) / 24) - ((pos.x - 320) / 48));
where pos.x and pos.y are the position of the mouse, 240 and 320 are the offset, 24 and 48 the size of the tile. Position then contains the grid coordinate of the tile I'm hovering over. This works reasonably well on a flat surface.
Now I'm adding height, which the math does not take into account.
This grid is a 2D grid containing noise, that's being translated to height and tile type. Height is really just an adjustment to the 'Y' position of the tile, so it's possible for two tiles to be drawn in the same spot.
I don't know how to determine which tile I'm hovering over.
edit:
Made some headway... Before, I was depending on the mouseover event to calculate grid position. I just changed this to do the calculation in the draw loop itself, and check if the coordinates are within the limits of the tile currently being drawn. creates some overhead tho, not sure if I'm super happy with it but I'll confirm if it works.
edit 2018:
I have no answer, but since this ha[sd] an open bounty, help yourself to some code and a demo
The grid itself is, simplified;
let grid = [[10,15],[12,23]];
which leads to a drawing like:
for (var i = 0; i < grid.length; i++) {
for (var j = 0; j < grid[0].length; j++) {
let x = (j - i) * resourceWidth;
let y = ((i + j) * resourceHeight) + (grid[i][j] * -resourceHeight);
// the "+" bit is the adjustment for height according to perlin noise values
}
}
edit post-bounty:
See GIF. The accepted answer works. The delay is my fault, the screen doesn't update on mousemove (yet) and the frame rate is low-ish. It's clearly bringing back the right tile.
Source
Intresting task.
Lets try to simplify it - lets resolve this concrete case
Solution
Working version is here: https://github.com/amuzalevskiy/perlin-landscape (changes https://github.com/jorgt/perlin-landscape/pull/1 )
Explanation
First what came into mind is:
Just two steps:
find an vertical column, which matches some set of tiles
iterate tiles in set from bottom to top, checking if cursor is placed lower than top line
Step 1
We need two functions here:
Detects column:
function getColumn(mouseX, firstTileXShiftAtScreen, columnWidth) {
return (mouseX - firstTileXShiftAtScreen) / columnWidth;
}
Function which extracts an array of tiles which correspond to this column.
Rotate image 45 deg in mind. The red numbers are columnNo. 3 column is highlighted. X axis is horizontal
function tileExists(x, y, width, height) {
return x >= 0 & y >= 0 & x < width & y < height;
}
function getTilesInColumn(columnNo, width, height) {
let startTileX = 0, startTileY = 0;
let xShift = true;
for (let i = 0; i < columnNo; i++) {
if (tileExists(startTileX + 1, startTileY, width, height)) {
startTileX++;
} else {
if (xShift) {
xShift = false;
} else {
startTileY++;
}
}
}
let tilesInColumn = [];
while(tileExists(startTileX, startTileY, width, height)) {
tilesInColumn.push({x: startTileX, y: startTileY, isLeft: xShift});
if (xShift) {
startTileX--;
} else {
startTileY++;
}
xShift = !xShift;
}
return tilesInColumn;
}
Step 2
A list of tiles to check is ready. Now for each tile we need to find a top line. Also we have two types of tiles: left and right. We already stored this info during building matching tiles set.
function getTileYIncrementByTileZ(tileZ) {
// implement here
return 0;
}
function findExactTile(mouseX, mouseY, tilesInColumn, tiles2d,
firstTileXShiftAtScreen, firstTileYShiftAtScreenAt0Height,
tileWidth, tileHeight) {
// we built a set of tiles where bottom ones come first
// iterate tiles from bottom to top
for(var i = 0; i < tilesInColumn; i++) {
let tileInfo = tilesInColumn[i];
let lineAB = findABForTopLineOfTile(tileInfo.x, tileInfo.y, tiles2d[tileInfo.x][tileInfo.y],
tileInfo.isLeft, tileWidth, tileHeight);
if ((mouseY - firstTileYShiftAtScreenAt0Height) >
(mouseX - firstTileXShiftAtScreen)*lineAB.a + lineAB.b) {
// WOHOO !!!
return tileInfo;
}
}
}
function findABForTopLineOfTile(tileX, tileY, tileZ, isLeftTopLine, tileWidth, tileHeight) {
// find a top line ~~~ a,b
// y = a * x + b;
let a = tileWidth / tileHeight;
if (isLeftTopLine) {
a = -a;
}
let b = isLeftTopLine ?
tileY * 2 * tileHeight :
- (tileX + 1) * 2 * tileHeight;
b -= getTileYIncrementByTileZ(tileZ);
return {a: a, b: b};
}
Please don't judge me as I am not posting any code. I am just suggesting an algorithm that can solve it without high memory usage.
The Algorithm:
Actually to determine which tile is on mouse hover we don't need to check all the tiles. At first we think the surface is 2D and find which tile the mouse pointer goes over with the formula OP posted. This is the farthest probable tile mouse cursor can point at this cursor position.
This tile can receive mouse pointer if it's at 0 height, by checking it's current height we can verify if this is really at the height to receive pointer, we mark it and move forward.
Then we find the next probable tile which is closer to the screen by incrementing or decrementing x,y grid values depending on the cursor position.
Then we keep on moving forward in a zigzag fashion until we reach a tile which cannot receive pointer even if it is at it's maximum height.
When we reach this point the last tile found that were at a height to receive pointer is the tile that we are looking for.
In this case we only checked 8 tiles to determine which tile is currently receiving pointer. This is very memory efficient in comparison to checking all the tiles present in the grid and yields faster result.
One way to solve this would be to follow the ray that goes from the clicked pixel on the screen into the map. For that, just determine the camera position in relation to the map and the direction it is looking at:
const camPos = {x: -5, y: -5, z: -5}
const camDirection = { x: 1, y:1, z:1}
The next step is to get the touch Position in the 3D world. In this certain perspective that is quite simple:
const touchPos = {
x: camPos.x + touch.x / Math.sqrt(2),
y: camPos.y - touch.x / Math.sqrt(2),
z: camPos.z - touch.y / Math.sqrt(2)
};
Now you just need to follow the ray into the layer (scale the directions so that they are smaller than one of your tiles dimensions):
for(let delta = 0; delta < 100; delta++){
const x = touchPos.x + camDirection.x * delta;
const y = touchPos.y + camDirection.y * delta;
const z = touchPos.z + camDirection.z * delta;
Now just take the tile at xz and check if y is smaller than its height;
const absX = ~~( x / 24 );
const absZ = ~~( z / 24 );
if(tiles[absX][absZ].height >= y){
// hanfle the over event
}
I had same situation on a game. first I tried with mathematics, but when I found that the clients wants to change the map type every day, I changed the solution with some graphical solution and pass it to the designer of the team. I captured the mouse position by listening the SVG elements click.
the main graphic directly used to capture and translate the mouse position to my required pixel.
https://blog.lavrton.com/hit-region-detection-for-html5-canvas-and-how-to-listen-to-click-events-on-canvas-shapes-815034d7e9f8
https://code.sololearn.com/Wq2bwzSxSnjl/#html
Here is the grid input I would define for the sake of this discussion. The output should be some tile (coordinate_1, coordinate_2) based on visibility on the users screen of the mouse:
I can offer two solutions from different perspectives, but you will need to convert this back into your problem domain. The first methodology is based on coloring tiles and can be more useful if the map is changing dynamically. The second solution is based on drawing coordinate bounding boxes based on the fact that tiles closer to the viewer like (0, 0) can never be occluded by tiles behind it (1,1).
Approach 1: Transparently Colored Tiles
The first approach is based on drawing and elaborated on here. I must give the credit to #haldagan for a particularly beautiful solution. In summary it relies on drawing a perfectly opaque layer on top of the original canvas and coloring every tile with a different color. This top layer should be subject to the same height transformations as the underlying layer. When the mouse hovers over a particular layer you can detect the color through canvas and thus the tile itself. This is the solution I would probably go with and this seems to be a not so rare issue in computer visualization and graphics (finding positions in a 3d isometric world).
Approach 2: Finding the Bounding Tile
This is based on the conjecture that the "front" row can never be occluded by "back" rows behind it. Furthermore, "closer to the screen" tiles cannot be occluded by tiles "farther from the screen". To make precise the meaning of "front", "back", "closer to the screen" and "farther from the screen", take a look at the following:
.
Based on this principle the approach is to build a set of polygons for each tile. So firstly we determine the coordinates on the canvas of just box (0, 0) after height scaling. Note that the height scale operation is simply a trapezoid stretched vertically based on height.
Then we determine the coordinates on the canvas of boxes (1, 0), (0, 1), (1, 1) after height scaling (we would need to subtract anything from those polygons which overlap with the polygon (0, 0)).
Proceed to build each boxes bounding coordinates by subtracting any occlusions from polygons closer to the screen, to eventually get coordinates of polygons for all boxes.
With these coordinates and some care you can ultimately determine which tile is pointed to by a binary search style through overlapping polygons by searching through bottom rows up.
It also matters what else is on the screen. Maths attempts work if your tiles are pretty much uniform. However if you are displaying various objects and want the user to pick them, it is far easier to have a canvas-sized map of identifiers.
function poly(ctx){var a=arguments;ctx.beginPath();ctx.moveTo(a[1],a[2]);
for(var i=3;i<a.length;i+=2)ctx.lineTo(a[i],a[i+1]);ctx.closePath();ctx.fill();ctx.stroke();}
function circle(ctx,x,y,r){ctx.beginPath();ctx.arc(x,y,r,0,2*Math.PI);ctx.fill();ctx.stroke();}
function Tile(h,c,f){
var cnv=document.createElement("canvas");cnv.width=100;cnv.height=h;
var ctx=cnv.getContext("2d");ctx.lineWidth=3;ctx.lineStyle="black";
ctx.fillStyle=c;poly(ctx,2,h-50,50,h-75,98,h-50,50,h-25);
poly(ctx,50,h-25,2,h-50,2,h-25,50,h-2);
poly(ctx,50,h-25,98,h-50,98,h-25,50,h-2);
f(ctx);return ctx.getImageData(0,0,100,h);
}
function put(x,y,tile,image,id,map){
var iw=image.width,tw=tile.width,th=tile.height,bdat=image.data,fdat=tile.data;
for(var i=0;i<tw;i++)
for(var j=0;j<th;j++){
var ijtw4=(i+j*tw)*4,a=fdat[ijtw4+3];
if(a!==0){
var xiyjiw=x+i+(y+j)*iw;
for(var k=0;k<3;k++)bdat[xiyjiw*4+k]=(bdat[xiyjiw*4+k]*(255-a)+fdat[ijtw4+k]*a)/255;
bdat[xiyjiw*4+3]=255;
map[xiyjiw]=id;
}
}
}
var cleanimage;
var pickmap;
function startup(){
var water=Tile(77,"blue",function(){});
var field=Tile(77,"lime",function(){});
var tree=Tile(200,"lime",function(ctx){
ctx.fillStyle="brown";poly(ctx,50,50,70,150,30,150);
ctx.fillStyle="forestgreen";circle(ctx,60,40,30);circle(ctx,68,70,30);circle(ctx,32,60,30);
});
var sheep=Tile(200,"lime",function(ctx){
ctx.fillStyle="white";poly(ctx,25,155,25,100);poly(ctx,75,155,75,100);
circle(ctx,50,100,45);circle(ctx,50,80,30);
poly(ctx,40,70,35,80);poly(ctx,60,70,65,80);
});
var cnv=document.getElementById("scape");
cnv.width=500;cnv.height=400;
var ctx=cnv.getContext("2d");
cleanimage=ctx.getImageData(0,0,500,400);
pickmap=new Uint8Array(500*400);
var tiles=[water,field,tree,sheep];
var map=[[[0,0],[1,1],[1,1],[1,1],[1,1]],
[[0,0],[1,1],[1,2],[3,2],[1,1]],
[[0,0],[1,1],[2,2],[3,2],[1,1]],
[[0,0],[1,1],[1,1],[1,1],[1,1]],
[[0,0],[0,0],[0,0],[0,0],[0,0]]];
for(var x=0;x<5;x++)
for(var y=0;y<5;y++){
var desc=map[y][x],tile=tiles[desc[0]];
put(200+x*50-y*50,200+x*25+y*25-tile.height-desc[1]*20,
tile,cleanimage,x+1+(y+1)*10,pickmap);
}
ctx.putImageData(cleanimage,0,0);
}
var mx,my,pick;
function mmove(event){
mx=Math.round(event.offsetX);
my=Math.round(event.offsetY);
if(mx>=0 && my>=0 && mx<cleanimage.width && my<cleanimage.height && pick!==pickmap[mx+my*cleanimage.width])
requestAnimationFrame(redraw);
}
function redraw(){
pick=pickmap[mx+my*cleanimage.width];
document.getElementById("pick").innerHTML=pick;
var ctx=document.getElementById("scape").getContext("2d");
ctx.putImageData(cleanimage,0,0);
if(pick!==0){
var temp=ctx.getImageData(0,0,cleanimage.width,cleanimage.height);
for(var i=0;i<pickmap.length;i++)
if(pickmap[i]===pick)
temp.data[i*4]=255;
ctx.putImageData(temp,0,0);
}
}
startup(); // in place of body.onload
<div id="pick">Move around</div>
<canvas id="scape" onmousemove="mmove(event)"></canvas>
Here the "id" is a simple x+1+(y+1)*10 (so it is nice when displayed) and fits into a byte (Uint8Array), which could go up to 15x15 display grid already, and there are wider types available too.
(Tried to draw it small, and it looked ok on the snippet editor screen but apparently it is still too large here)
Computer graphics is fun, right?
This is a special case of the more standard computational geometry "point location problem". You could also express it as a nearest neighbour search.
To make this look like a point location problem you just need to express your tiles as non-overlapping polygons in a 2D plane. If you want to keep your shapes in a 3D space (e.g. with a z buffer) this becomes the related "ray casting problem".
One source of good geometry algorithms is W. Randolf Franklin's website and turf.js contains an implementation of his PNPOLY algorithm.
For this special case we can be even faster than the general algorithms by treating our prior knowledge about the shape of the tiles as a coarse R-tree (a type of spatial index).

2D top-down minimap

I'd like to make a minimap of my rpg game.
Is making a minimap as simple as dividing all object dimensions, velocities, and coordinates by however large you want the minimap?
For example below... You have a size of 1000x1000px, a canvas (viewport) of 500x500px, the player is located in the center of the viewport... If you wanted a minimap half the size of the actual world, you would do:
Player/Viewport x,y velocity/2
Player/Viewport x,y coordinates/2
Canvas, world, and all objects' width and height are divided by 2
etc...
That way the rendering of the minimap on the world and the velocities are scaled accurately? Am I missing anything?
Thanks!
EDIT: Something like this?
function miniMap() {
$(".minimapHolder").show();
$("#mini_map").text("hide minimap");
var minicanvas = document.getElementById("miniMap");
ministage = new createjs.Stage("miniMap");
minicam = new createjs.Shape();
minicam.graphics.beginStroke("white").drawRoundRect(0, 0, 100, 40, 5);
//blip representation of Player
player_blip = new createjs.Shape();
player_blip.graphics.beginFill("yellow").drawRoundRect(0, 0, 11.2, 12, 1);
animal_blip = new createjs.Shape();
animal_blip.graphics.beginFill("red").drawRoundRect(0, 0, 24.4, 21.6, 1);
player_blip.x = players_Array[0].x/5;
player_blip.y = players_Array[0].y/5;
animal_blip.x = animalContainer.x/5;
animal_blip.y = animalContainer.y/5;
minicam.x = players_Array[0].x-110;
minicam.y = players_Array[0].y-110;
ministage.addChild(player_blip, animal_blip, minicam);
ministage.update();
}
function updateMiniMap() {
player_blip.x = players_Array[0].x/5;
player_blip.y = players_Array[0].y/5;
if (ContainerOfAnimals.children[0] != null) {
var pt = ContainerOfAnimals.localToGlobal(ContainerOfAnimals.children[0].x, ContainerOfAnimals.children[0].y);
console.log(pt.x);
animal_blip.x = pt.x/5;
animal_blip.y = pt.y/5;
} else {
ministage.removeChild(animal_blip);
}
minicam.x = player_blip.x-40;
minicam.y = player_blip.y-15;
ministage.update();
}
Gives:
Short anwswer: "It will(most likely) work." ... but:
What you are trying to achieve is just scaling the stage/container, so you could also just use a copy of everything and put it into a container and scale it down to 0.5, but that is not the purpose of a minimap.
Objects of the minimap should only be a representation of the object in the 'real' world and should therefore not have any velocity ect.(that should especially not be updated separately from the 'real' world) - while your approach will probably work, you'd allways have to keep track and update every property, this will get messy quickly or even lead to differences if you miss some tiny things.
A more 'clean'(and simple) approach to this would be, that each minimap-object has a reference to the object in the 'real' world and on each tick, it just reads the x/y-coordinates and updates its' own coordinates based on the minimap-scale.
Another thing is the graphics: Scaling-operations can be costly(performance wise), especially when they are done each frame, so IF you use the same graphics for the minimap you should at least used a cached DisplayObject and not have the graphics scaled each frame.

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