Typical depth buffers in a 3D graphics pipeline are not linear. Perspective division causes depths in normalized device coordinates to be on a different scale. (See also here.) So the z-coordinate you’re feeding into unprojectPoint isn’t actually the one you want. How, then, to find the normalized-depth coordinate matching a plane in world space? Well, … Read more
For smooth surfaces (no edges) I do it like this: create space for per vertex double N[3]; //normal int cnt; per vertex init N={0.0,0.0,0.0} cnt=0; compute per face normal normal must be normalized length=1.0 !!! add this Normal to all vertexes used in face and increment cnt to all vertexes used in face per vertex … Read more
Here is an overview of a few methods to render with transparency in OpenGL, with advantages and disadvantages for each. Alpha Testing This is a very limited method, but is sufficient for the specific case the poster asked about. The example shown does not really need transparency because everything is either fully opaque or fully … Read more
I’ve written for my project the following function; it receives an THREE.Object3D instance and a camera as a parameters and returns the position on the screen. function toScreenPosition(obj, camera) { var vector = new THREE.Vector3(); var widthHalf = 0.5*renderer.context.canvas.width; var heightHalf = 0.5*renderer.context.canvas.height; obj.updateMatrixWorld(); vector.setFromMatrixPosition(obj.matrixWorld); vector.project(camera); vector.x = ( vector.x * widthHalf ) + widthHalf; … Read more
I see this question is a bit old, but I decided to give an answer anyway for those who find this question by searching. The standard way to represent 2D/3D transformations nowadays is by using homogeneous coordinates. [x,y,w] for 2D, and [x,y,z,w] for 3D. Since you have three axes in 3D as well as translation, … Read more
What you really have is Volumetric data. I guess that you have is a value of C for every X,Y,Z. And it actually depends a lot in what type of data you have. You’d need to give more information for an specific answer. In general have a look to Volumetric data visualization techniques, but there … Read more
I am used to OpenGL style render math so I stick to it (all the renders use almost the same math) First some therms to explain: Transform matrix Represents a coordinate system in 3D space double m[16]; // it is 4×4 matrix stored as 1 dimensional array for speed m[0]=xx; m[4]=yx; m[ 8]=zx; m[12]=x0; m[1]=xy; … Read more
[Edit2] updated progress There may be more then just rotation present so I would try this instead: preprocess image You can apply many filters to remove noise from the image and or normalize illumination conditions (looks like your posted image does not need it). Then simply binarise the image to simplify further steps. see related: … Read more
File types that use separate indices for vertices and normals do not match to the OpenGL vertex model very directly. As you noticed, OpenGL uses a single set of indices. What you need to do is create an OpenGL vertex for each unique (vertex index, normal index) pair in your input. That takes a little … Read more
The pattern for instantiating an orthographic camera in three.js is: var camera = new THREE.OrthographicCamera( width / – 2, width / 2, height / 2, height / – 2, near, far ); where width and height are the width and height of the camera’s cuboid-shaped frustum measured in world-space units. near and far are the … Read more