c++ - OpenGL Asymmetric Frustum for Desktop VR -


i making opengl c++ application tracks users location in relation screen , updates rendered scene perspective of user. know "desktop vr" or can think of screen diorama or fish tank. rather new opengl , have defined simple scene far, cube, , rendered correctly.

the problem when start moving , want rerender cube scene, projection plane seems translated , don't see think should. want plane fixed. if writing ray tracer, window fixed, eye allowed wander. can please explain me how can achieve effect desire (pinning viewing window) while having camera/eye wander @ non-origin coordinate?

all of examples find demand camera/eye @ origin, not conceptually convenient me. also, because "fish tank", setting d_near xy-plane, z = 0.

in screen/world space, assign center of screen (0,0,0) , 4 corners to: tl(-44.25, 25, 0) tr( 44.25, 25, 0) br( 44.25,-25, 0) bl(-44.25,-25, 0) these values in cm 16x9 display.

i calculate user's eye (actually web cam on face) using posit somewhere in range of (+/-40, +/-40, 40-250). posit method accurate.

i defining own matrices perspective , viewing transforms , using shaders.

i initialize follows:

float right = 44.25; float left = -44.25; float top = 25.00; float bottom = -25.00;   vec3 eye = vec3(0.0, 0.0, 100.0); vec3 view_dir = vec3(0.0, 0.0, -1.0); vec3 = vec3(0.0, 1.0, 0.0); vec3 n = normalize(-view_dir); vec3 u = normalize(cross(up, n));  vec3 v = normalize(cross(n, u));  float d_x = -(dot(eye, u)); float d_y = -(dot(eye, v)); float d_z = -(dot(eye, n));  float d_near = eye.z; float d_far = d_near + 50;  // perspective transform matrix mat4 p = mat4((2.0*d_near)/(right-left ), 0, (right+left)/(right-left), 0,              0, (2.0*d_near)/(top-bottom), (top+bottom)/(top-bottom), 0,             0, 0, -(d_far+d_near)/(d_far-d_near), -(2.0*d_far*d_near)/(d_far-d_near),             0, 0, -1.0, 0);  // viewing transform matrix mat4 v = mat4(u.x, u.y, u.z, d_x,               v.x, v.y, v.z, d_y,               n.x, n.y, n.z, d_z,               0.0, 0.0, 0.0, 1.0);  mat4 mv = c * v; //mv = v;

from gather looking on web, view_dir , remain fixed. means need update d_near , d_far d_x, d_y, , d_y? in glutidlefunc( idle );

void idle (void) {        hbuffer->getframe(hframe);     if (hframe->goodh && hframe->timestamp != timestamp) {         timestamp = hframe->timestamp;         std::cout << "(" << hframe->eye.x << ", " <<                     hframe->eye.y << ", " <<                     hframe->eye.z << ") \n";          eye = vec3(hframe->eye.x, hframe->eye.y, hframe->eye.z);          d_near = eye.z;         d_far = eye.z + 50;          p = mat4((2.0*d_near)/(right-left), 0, (right+left)/(right-left), 0,                   0, (2.0*d_near)/(top-bottom), (top+bottom)/(top-bottom), 0,                  0, 0, -(d_far+d_near)/(d_far-d_near), -(2.0*d_far*d_near)/(d_far-d_near),                  0, 0, -1.0, 0);          d_x = -(dot(eye, u));         d_y = -(dot(eye, v));         d_z = -(dot(eye, n));          c = mat4(1.0, 0.0, 0.0, eye.x,                  0.0, 1.0, 0.0, eye.y,                  0.0, 0.0, 1.0, 0.0,                  0.0, 0.0, 0.0, 1.0);          v = mat4(u.x, u.y, u.z, d_x,                  v.x, v.y, v.z, d_y,                  n.x, n.y, n.z, d_z,                  0.0, 0.0, 0.0, 1.0);          mv = c * v;         //mv = v;          glutpostredisplay();     } }

here shader code:

#version 150  uniform mat4 mv; uniform mat4 p; in vec4 vposition; in vec4 vcolor; out vec4 color;  void  main()  {      gl_position = p * mv * vposition;     color = vcolor; }

ok, made changes code, without success. when use v in place of mv in vertex shader, looks want to, perspective correct , objects right size, however, scene translated displacement of camera.

when using c , v obtain mv, scene rendered perspective of observer straight on , rendered scene fills window should, perspective of eye/camera lost.

really, want translate 2d pixels, projection plane, appropriate x , y values of eye/camera, keep center of object (whose xy center (0,0)) in center of rendered image. guided examples in textbook "interactive computer graphics: top-down approach shader-based opengl (6th edition)". using files paired book freely available on web, continuing row major approach.

the following images taken when not using matrix c create mv. when use c create mv, scenes first image below. desire no translation in z , leave 0.

because projection plane , camera plane parallel, conversion 1 other coordinate system translation , inv(t) ~ -t.

here image eye @ (0,0,50): here image eye @ (0,0,50):

here image eye @ (56,-16,50): here image eye @ (56,-16,50):

the solution update d_x, d_y, , d_z, accounting new eye position, never change u, v, or n. in addition, 1 must update matrix p new values left, right, top , bottom, relate new position of camera/eye.

i initialize this:

float screen_right = 44.25; float screen_left = -44.25; float screen_top = 25.00; float screen_bottom = -25.00;  float screen_front = 0.0; float screen_back = -150;

and idle function looks this, note calculations top, bottom, right, , left:

void idle (void) {    hbuffer->getframe(&hframe); if (hframe.goodh && hframe.timestamp != timestamp) {     timestamp = hframe.timestamp;     //std::cout << "(" << hframe.eye.x << ", " <<     //                  hframe.eye.y << ", " <<     //                  hframe.eye.z << ") \n";      eye = vec3(hframe.eye.x, hframe.eye.y, hframe.eye.z);      d_near = eye.z;     d_far = eye.z + abs(screen_back) + 1;      float top = screen_top - eye.y;     float bottom = top - 2*screen_top;     float right = screen_right - eye.x;     float left = right - 2*screen_right;      p = mat4((2.0 * d_near)/(right - left ), 0.0, (right + left)/(right - left), 0.0,               0.0, (2.0 * d_near)/(top - bottom), (top + bottom)/(top - bottom), 0.0,              0.0, 0.0, -(d_far + d_near)/(d_far - d_near), -(2.0 * d_far * d_near)/(d_far - d_near),              0.0, 0.0, -1.0, 0.0);      d_x = -(dot(eye, u));     d_y = -(dot(eye, v));     d_z = -(dot(eye, n));      v = mat4(u.x, u.y, u.z, d_x,              v.x, v.y, v.z, d_y,              n.x, n.y, n.z, d_z,              0.0, 0.0, 0.0, 1.0);      glutpostredisplay(); }

}

this redefinition of perspective matrix keeps rendered image translating. still have camera capture , screen grabbing synchronization issues, able create images following updated in real-time position of user:

enter image description here


Comments

Post a Comment

Popular posts from this blog

Why does Ruby on Rails generate add a blank line to the end of a file? -

running rails generate controller foo home results in: class foocontroller < application controller def home end end (there's nothing on line in actual file, blank line) is there purpose blank line? it's common use newline indicate end of line, last line. many editors (like vi, use) add in newline silently. consensus text files (especially in unix world) should end in newline, , there have been problems historically if wasn't present. why should text files end newline? the tool used count lines in file "wc" counts newlines in file, without trailing newline show 3 instead of 4. it improves readability of templates used in generator. consider: https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/controller/templates/controller.rb to remove trailing newline, template have last line of: end<% end -%> instead of: end <% end -%> that seems less readable me. the discussion below refers
Read more

keyboard - Smiles and long press feature in Android -

i've created android keyboard. how add features inserting smilies, , using long keypresses display symbols? to create long-press behavior allows select several options pop-up menu, follow guide (specifically pop-up menu section): http://developer.android.com/guide/topics/ui/menus.html smileys (also known emoticons) combination of keys, understood programs , parsed same way. have do, when clicks smiley face on keyboard, simulate pressing of key combination matching emoticon. example, when clicks smiley, should simulate key presses ':' , ')' :). here's list of emoticons: http://en.wikipedia.org/wiki/list_of_emoticons
Read more

node.js - Bad Request - node js ajax post -

i'm using express 3.0 , node v0.11.0. have button submits form , i'm using ajax post data json object node server. client code is: $('#contact').submit(function(e) { console.log('submit called'); var formdata = json.stringify($('form').serializeobject()); console.log(formdata); $.ajax({ url: "http://localhost:3000/savedata/", type: "post", datatype: 'json', data: {objectdata: formdata}, contenttype: "application/json", complete: function() { console.log('process complete'); }, success: function(data) { console.log('process sucess'); }, error: function() { console.log('process error'); }, }); return false; }); then on server: var express = require('express'); var app = express(); app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.bodyparser());
Read more