vertex

问题 I have attribute contains pixels values. And i want to offset my gl_vertex with this attribute value. The problem is that my gl_vertex is in world units and the offset\attribute is in pixels. I can do it if i'm sending the screen size as uniforms and then convert the pixels to -1 to 1 values, and add it to the final gl_Position. But i don't want now to manage screen size events and sending it anyway every draw, every shader that i have. It there any way to do it with some matrix play, or

问题 Ok... I'm doing simple OpenGL ES programming and when I say simple, the most complicated things I do aren't much more than glorified beveled cubes and L-shapes. (Think very Tetris but in 3D.) However, getting all that vertex data into an app is either a) hand-coded (UGH!) or b) 3rd-party game engine (double-UGH!!!) or you use some 3rd-party filetype importer. (Partial Ugh!) With one exception. I've been using a program on the Mac called Cheetah3D which is a pretty good modeler (not great, but

问题 I am implementing a graph class using a Map as an adjacency list, with a simple class Vertex that I am using to represent each node in the graph: export class Vertex { constructor(value) { if (value) this.value = value; else throw new Error("Value must be specified"); } getValue() { return this.value; } setValue(value) { if (value) this.value = value; else throw new Error("Value must be specified"); } } Then in my graph class I have implemented a constructor and 2 methods for adding vertices

问题 I'm writing a 3D modeling application using GLScene , so I need to move some vertices under mouse position to new position by grabbing the vertex. First of all, I load a sphere and pick up a vertex by mouse,then I try to drag it but I realize that the vertex doesn't move under mouse caret correctly. unit Unit1; interface uses Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Math, //GLScene

问题 I was looking for ways to associate attributes with arbitrary groupings of verticies, at first instancing appeared to be the only way for me to accomplish this, but then I stumbled up this question and this answer states : However what is possible with newer versions of OpenGL is setting the rate at which a certain vertex attribute's buffer offset advances. Effectively this means that the data for a given vertex array gets duplicated to n vertices before the buffer offset for a attribute

问题 In opengl, is it bad practice or not recommended to modify the vertex array after I have drawn it? 回答1: It's not bad practice if you modify the vertex array when you draw it as ordinary vertex array. It's bad practice to modify the vertex array if you use vertex buffer objects in your draw method. That's because you have to reupload it to your VRAM once it is edited. 来源： https://stackoverflow.com/questions/4703550/android-opengl-modify-vertex-array-after-draw-call

问题 Everything I've found seems to indicate that in order to export a vertex animation a point cache file must also be generated, but that means in addition to the FBX file a whole new folder with that cache data must also be built. Is there no way to store the (vertex) animation data entirely in the FBX file? 回答1: That's correct. The FBX stores the mesh/topology, and the point cache stores the offsets of the vertices over time. 回答2: The FBX file format stores mesh topology, shapes and skin

问题 I'm trying to create a grid of points by calculating vertex positions dynamically, based on their index in the array of vertices sent to the shader. Is there an equivalent of the gl_VertexID variable that I can call from within my shader? Or another way of accessing their position in the array without having to send more data to the GPU? Thank, Josh. Here's my vertex shader: attribute vec4 vertexPosition; uniform mat4 modelViewProjectionMatrix; vec4 temp; uniform float width; void main() {

问题 I'm trying to create a grid of points by calculating vertex positions dynamically, based on their index in the array of vertices sent to the shader. Is there an equivalent of the gl_VertexID variable that I can call from within my shader? Or another way of accessing their position in the array without having to send more data to the GPU? Thank, Josh. Here's my vertex shader: attribute vec4 vertexPosition; uniform mat4 modelViewProjectionMatrix; vec4 temp; uniform float width; void main() {

问题 I'm attempting to hack and modify several rendering features of an old opengl fixed pipeline game, by hooking into OpenGl calls, and my current mission is to implement shader lighting. I've already created an appropriate shader program that lights most of my objects correctly, but this game's terrain is drawn with no normal data provided. The game calls: void glVertexPointer(GLint size, GLenum type, GLsizei stride, const GLvoid * pointer); and void glDrawElements(GLenum mode, GLsizei count,