c++ - OpenGL: Perspective matrix shows nothing -


i doing basic opengl qt in order try , simple geometry render. i've created cube between (-1,-1,-1) , (1,1,1) , rotated overall shape recognisable, , can see if use orthographic projection matrix:

qmatrix4x4 orthographicmatrix(float top, float bottom, float left, float right, float near, float far) {     return qmatrix4x4((2.0f)/(right-left), 0, 0, -(right+left)/(right-left),                       0, (2.0f)/(top-bottom), 0, -(top+bottom)/(top-bottom),                       0, 0, -(2.0f)/(far-near), -(far+near)/(far-near),                       0, 0, 0, 1); }  ...  qmatrix4x4 projection = orthographicmatrix(2, -2, 2, -2, 0.01f, 2);

the formula generating orthographic/projection matrices taken https://solarianprogrammer.com/2013/05/22/opengl-101-matrices-projection-view-model/

this matrix allows me see cube if translate camera 1 on z:

cube visible

however, if use perspective matrix (again using formula linked page):

qmatrix4x4 perspectivematrix(float fov, float aspectratio, float near, float far) {     float top = near * qtan((m_pi/180.0f) * (fov/2.0f));     float bottom = -top;     float right = top * aspectratio;     float left = -right;      return qmatrix4x4((2.0f-near)/(right-left), 0, (right+left)/(right-left), 0,                       0, (2.0f-near)/(top-bottom), (top+bottom)/(top-bottom), 0,                       0, 0, -(far+near)/(far-near), -(2.0f-far-near)/(far-near),                       0, 0, -1, 0); }  ...  qmatrix4x4 projection = perspectivematrix(60.0f, (float)width()/(float)height(), 0.01f, 2);

i no geometry displaying @ same camera position:

no geometry showing.

i've checked code many times , can't work out why nothing shows up. gather must perspective matrix code seems follow specified on solarian programmer page. wrong here?

for reference, shaders are:

// vertex #version 330 core in vec3 vertexposition_modelspace; uniform mat4 mvp; void main() {     vec4 v = vec4(vertexposition_modelspace,1);     gl_position = mvp * v; }  // fragment #version 330 core out vec3 color; float remap(float inp) {     while (inp>200.0) inp-=200.0;     return inp/200.0; }  void main() {     color = vec3(remap(gl_fragcoord.x), remap(gl_fragcoord.y), 0); }

it seems made mistakes implementing perspective matrix reference.

for example, first entry (2.0f-near)/(right-left) in code while (2.0f * near)/(right-left) on website. similar errors in other fields of matrix.


Comments

Post a Comment

Popular posts from this blog

html - Outlook 2010 Anchor (url/address/link) -

i'm trying link specific pdf page msoutlook'10 or msword'10, #page=... anchor particularly useful , works fine elsewhere. unfortunately when click [ctr-k] in outlook or winword, links re-formatted assuming unc path. pdf file located on shared drive. using "file:" prefix links open pdf in adobe reader (outside of browser), , "http:" open inside browser. issue seem need open in browser "file:" prefix in order anchor work. know anchors work inside browser. outlook uses windows/explorer default program (based on file extension) seems open in adobe reader neglecting anchor. is aware of solution, link specific page or bookmark of shared-pdf ms outlook and/or winword link? common references: mailermailer.com/...anchor-tags-html-emails campaignmonitor.com/...anchor-links-in-email-newsletters/ stackoverflow.com/...anchor-in-pdf-document
Read more

javascript - Why does running this loop 9 times take 100x longer than running it 8 times? -

consider code: test = function() { } t = new test(); (var = 0; < 8; i++) { result = t instanceof test; } if change number of iterations 8 9 , loop take 100 times longer complete in latest version of firefox (41.0.1). tested on 2 different pcs , magic limit 8. here jsperf test used: http://jsperf.com/instanceof-8-times-vs-9-times does have idea why might happen? seems specific instanceof . not happen if else object, example check property. note: filed bugzilla bug this. jan de mooij mozilla team has posted details in bugzilla thread . here's simplistic interpretation of highly technical answers: in i < 8 case, firefox smart enough hoist result = t instanceof test; statement out of loop (according tests, doesn't seem omit altogether). in i < 9 case, apparently doesn't optimization . why? reason not clear, related fact 9 iterations threshold above function considered "hot" enough run through jit compiler. i < 8 cas...
Read more

Getting gateway time-out Rails app with Nginx + Puma running on Digital Ocean -

following this guide setup app on digital ocean droplet, not working. site not loading , it's throwing: "gateway time-out". the puma server works, since ps aux | grep puma prints: root 15878 0.0 0.4 376832 2168 ? sl 12:50 0:00 puma 2.13.4 (unix:///var/www/myapp/shared/tmp/sockets/myapp-puma.sock) [20150930164940] root 15881 0.0 0.7 903676 3692 ? sl 12:50 0:06 puma: cluster worker 0: 15878 [20150930164940] root 24654 0.0 0.1 11748 916 pts/2 s+ 18:00 0:00 grep --color=auto puma my nginx config: user root; worker_processes 1; events { worker_connections 1024; } http { upstream puma { server unix:///var/www/myapp/shared/tmp/sockets/myapp-puma.sock; } server { listen 80; server_name myapp.com; root /var/www/myapp/current/public; access_log /var/www/myapp/current/log/access.log; error_log /...
Read more