I have a quick question, may be someone will explain it to me.
The scene setup is show below. I have a sprite tree, a cube and a cubeCamera. Cube material has envMap set to cubeCamera.renderTarget. (CubeCamera is places where the cube is, and also i hide the cube before calling updateCubeMap method).
So, the question is why the sprite appears upside-down in the reflection?
This seems to happen only to sprites, other objects behave as expected.
In the actual project we manually flip sprites before updating cubeCamera, and it seems to work ok. But i want to actually know why is it so? Thanks!
UPD. Demo http://webgears.ru/public/wgdemos/spriteInEnvMap/
Related
Does anyone have any suggestion of how to implement such a light glow effect in Three.js ?
There is a TextGeometry mesh
Some BoxGeometry mesh as a background
How to make this glow between them?
I tried to put many PointLight between text and box, but after about 20 of PointLights the scene become very slow. I tried to put some RectAreaLights — but the same.
Does anyone have any suggestion of how to implement such a light glow effect in Three.js ?
The typical way of doing this is via post-processing. three.js offers a so called "Bloom" pass which is demonstrated in the following example: webgl_postprocessing_unreal_bloom. I suggest you start with this setup.
but after about 20 of PointLights the scene become very slow. I tried to put some RectAreaLights — but the same.
It's no good approach in general to add that number of light sources to a three.js scene. If you place some small sphere meshes (based on THREE.SphereGeometry) with a bright material color onto the text, you should get a good result with bloom pass.
After simplifying glb successfully with the answer in this post.
The textures in are not being applied to the model any more (it appears completely black and unreflective(no material)
How would I programmatically get the textures to work with this new simplified geometry?
I think its something to do with the uv's but im not to sure how to have it work according to simplified geometry, if even possible.
THREE.SimplifyModifier currently does not preserve UVs in the geometry, which you'll need for textures to work. See: https://github.com/mrdoob/three.js/issues/14058. There is a workaround suggested in that issue (via changes to SimplifyModifier) but as discussed there, some artifacts will likely be visible in the result. If you can do the simplification in Blender or another modeling tool, you may have more control over the process and can get better results.
I try to render both sides of a transparent object with three.js. Other objects located within the transparent object should show too. Sadly I get artifacts I don't know too handle. Here is a test page: https://dl.dropbox.com/u/3778149/webgl_translucency/test.html
Here is an image of the said artifact. They seem to stem from the underlying sphere geometry.
Interestingly the artifacts are not visible for blending mode THREE.SubtractiveBlending = 2.
Any help appreciated!
Alex
Self-transparency is particularly difficult in WebGL and three.js. You just have to really understand the issues, and then adapt your code to achieve the effect you want.
You can achieve the look of a double-sided, transparent sphere in three.js, with a trick: You need to render two transparent spheres -- one with material.side = THREE.BackSide, and one with material.side = THREE.FrontSide.
Using such methods is generally required if you want self-transparency without artifacts -- especially if you allow the camera or object to move.
three.js r.143
Generally to do transparent objects you need to sort them front to back (I'm guessing three.js already does this). If your object is convex (like both of those are) then you can sometimes get by by rendering each object twice, once with gl.cullFace(gl.CCW) and again with gl.cullFace(gl.CW). So for example if the cube is inside the sphere you'd effectively do
gl.enable(gl.CULL_FACE);
gl.cullFace(gl.CW);
drawSphere(); // draws the back of the sphere
drawCube(); // draws the back of the cube
gl.cullFace(gl.CCW);
drawCube(); // draws the front of the cube.
drawSphere(); // draws the front of the sphere.
I have no idea how to do that in three.js
This only handles objects that are convex and not intersecting (one object is contained entirely inside the other).
To render that scene correctly with alpha blending, the triangles would have to be rendered from back to front each frame. Your scene is particularly challenging since you have one object inside another, and rendering both sides, which would require rendering part of the sphere, then the cube, then the rest of the sphere. I doubt three.js (or any other scene graph library) can handle this case.
Additive or subtractive blending will work without sorting, but doesn't look as nice.
Make a clon of the original mesh and flip its normals; then make two identical "one sided" material for each with different name. Not the most classy approach but it worked just fine. I struggled with the same problem, this is what I did :P
The .json file looks like this:
{
"materials":[
{ "name":"ext", "texture":"f_03.jpg", "ambient":[255.0,255.0,255.0], "diffuse":[255.0,255.0,255.0], "specular":[255.0,255.0,255.0], "opacity":0.7 },
{ "name":"int", "texture":"f_03.jpg", "ambient":[255.0,255.0,255.0], "diffuse":[255.0,255.0,255.0], "specular":[255.0,255.0,255.0], "opacity":0.7 }
],
"meshes":[
{
"name":"Cylinder001",
"material":"ext", ...
{
"name":"Cylinder002",
"material":"int", ...
I have done the doubleSide rendering with depthTest off. This generate the rounded disc into my geometry I am curious to know the math behind this and why this happen.
My object is not transparent as you can see in the image Please explain about this.to me.
http://threejs.org/docs/#Reference/Materials/MeshDepthMaterial
In this example when you turn material doubleSide and turn of the depthTest you will get to know what I mean.
If you turn off depth testing then anything that is drawn later is on top of anything drawn before. Therefore if your object has parts that should be behind another part and you draw them later they will show incorrectly on top.
I try to render both sides of a transparent object with three.js. Other objects located within the transparent object should show too. Sadly I get artifacts I don't know too handle. Here is a test page: https://dl.dropbox.com/u/3778149/webgl_translucency/test.html
Here is an image of the said artifact. They seem to stem from the underlying sphere geometry.
Interestingly the artifacts are not visible for blending mode THREE.SubtractiveBlending = 2.
Any help appreciated!
Alex
Self-transparency is particularly difficult in WebGL and three.js. You just have to really understand the issues, and then adapt your code to achieve the effect you want.
You can achieve the look of a double-sided, transparent sphere in three.js, with a trick: You need to render two transparent spheres -- one with material.side = THREE.BackSide, and one with material.side = THREE.FrontSide.
Using such methods is generally required if you want self-transparency without artifacts -- especially if you allow the camera or object to move.
three.js r.143
Generally to do transparent objects you need to sort them front to back (I'm guessing three.js already does this). If your object is convex (like both of those are) then you can sometimes get by by rendering each object twice, once with gl.cullFace(gl.CCW) and again with gl.cullFace(gl.CW). So for example if the cube is inside the sphere you'd effectively do
gl.enable(gl.CULL_FACE);
gl.cullFace(gl.CW);
drawSphere(); // draws the back of the sphere
drawCube(); // draws the back of the cube
gl.cullFace(gl.CCW);
drawCube(); // draws the front of the cube.
drawSphere(); // draws the front of the sphere.
I have no idea how to do that in three.js
This only handles objects that are convex and not intersecting (one object is contained entirely inside the other).
To render that scene correctly with alpha blending, the triangles would have to be rendered from back to front each frame. Your scene is particularly challenging since you have one object inside another, and rendering both sides, which would require rendering part of the sphere, then the cube, then the rest of the sphere. I doubt three.js (or any other scene graph library) can handle this case.
Additive or subtractive blending will work without sorting, but doesn't look as nice.
Make a clon of the original mesh and flip its normals; then make two identical "one sided" material for each with different name. Not the most classy approach but it worked just fine. I struggled with the same problem, this is what I did :P
The .json file looks like this:
{
"materials":[
{ "name":"ext", "texture":"f_03.jpg", "ambient":[255.0,255.0,255.0], "diffuse":[255.0,255.0,255.0], "specular":[255.0,255.0,255.0], "opacity":0.7 },
{ "name":"int", "texture":"f_03.jpg", "ambient":[255.0,255.0,255.0], "diffuse":[255.0,255.0,255.0], "specular":[255.0,255.0,255.0], "opacity":0.7 }
],
"meshes":[
{
"name":"Cylinder001",
"material":"ext", ...
{
"name":"Cylinder002",
"material":"int", ...