![\"\"](\"https:\/\/demensdeum.com\/blog\/wp-content\/uploads\/2018\/08\/malevich.png\")
<\/p>\nMalevich periodically comes to any developer on OpenGL. This happens unexpectedly and boldly, you just start the project and see a black square instead of a wonderful render: <\/p>\n
<\/p>\n
Today I will describe for what reason I was visited by a black square, the problems found because of which Opengl does not draw anything on the screen, and sometimes even makes the window transparent. <\/p>\n
For debugging Opengl, two tools helped me: renderdoc <\/a> and I have an operating system Ubuntu 16.10 with old dependencies SDL2, GLM, Assimp, Glew. In the latest version of Ubuntu 18.04, I get the assembly of the game Death-Mask <\/a> which does not show anything on the screen (only a black square). When using Chroot and assembly at 16.10 I I get a working assembly of the game with graphics <\/strong>. <\/p>\n It seems something broke in Ubuntu 18.04 <\/p>\n LDD <\/strong> showed the linkka to identical libraries SDL2, GL. Driving a non -working build in Renderdoc, I saw garbage at the entrance to the vertex shader, but I needed a more solid confirmation. In order to understand the difference between the binarics, I drove them both through apitrace <\/strong>. Comparison of dumps showed me that the assembly on a fresh Ubunta breaks the program of the prospects in OpenGL, actually sending garbage there: <\/p>\n Matrices gather in the GLM library. After copying GLM from 16.04 – I got the working build of the game again. The problem was the difference in the initialization of a single matrix in GLM 9.9.0, it is necessary to clearly indicate the MAT4 (1.0F) argument in it in the constructor. Having changed the initialization and by writing off <\/a> the author of the library, I began to do tests for fsgl <\/a>. In the process of writing which I found flaws in FSGL, I will describe them further. <\/p>\n For the correct work with OpenGL, you need to voluntarily forcibly <\/em> <\/strong> request the context of a certain version. So it looks for SDL2 (you need to put the version strictly before initializing the context): <\/p>\n <\/p>\n For example, Renderdoc does not work with contexts below 3.2. I would like to note that after switching the context there is a high probability of seeing the same black screen <\/strong>. Why? I also met an interesting problem on Kubuntu, instead of a black square I was displayed transparent, and sometimes <\/strong> everything was rendered correctly. I found the solution to this problem at Stack Overflow: The FSGL test render code was also present Sleep (2S) <\/strong>; So on the Xubuntu and Ubuntu I received the correct render and sent the application to sleep, but on Kubuntu I received a transparent screen in 80% of the launch of Dolphin and 30% of launches and terminal. To solve this problem, I added rendering in each frame, after a SDlevent survey, as recommended in the documentation. <\/p>\n Test code: Opengl supports the communication channel between the application and the driver, to activate it, you need to turn on the flags Gl_debug_outPut, GL_DEBUG_OUTPUT_SYNCHRONUS, affix the warning GLDEBUGMESSAGECONTROL <\/SPAN> and tie the calback through GLDEBUGMESSAGECALLBACK <\/SPAN>. Malevich periodically comes to any developer on OpenGL. This happens unexpectedly and boldly, you just start the project and see a black square instead of a wonderful render: Today I will describe for what reason I was visited by a black square, the problems found because of which Opengl does not draw anything on theContinue reading “We beat Malevich, black squares Opengl”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[49,61,52],"tags":[],"class_list":["post-1440","post","type-post","status-publish","format-standard","hentry","category-blog","category-techie","category-tutorials","entry"],"translation":{"provider":"WPGlobus","version":"3.0.2","language":"hi","enabled_languages":["en","ru","zh","de","fr","ja","pt","hi"],"languages":{"en":{"title":true,"content":true,"excerpt":false},"ru":{"title":true,"content":true,"excerpt":false},"zh":{"title":true,"content":true,"excerpt":false},"de":{"title":true,"content":true,"excerpt":false},"fr":{"title":true,"content":true,"excerpt":false},"ja":{"title":true,"content":true,"excerpt":false},"pt":{"title":true,"content":true,"excerpt":false},"hi":{"title":false,"content":false,"excerpt":false}}},"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/posts\/1440","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/comments?post=1440"}],"version-history":[{"count":23,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/posts\/1440\/revisions"}],"predecessor-version":[{"id":4220,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/posts\/1440\/revisions\/4220"}],"wp:attachment":[{"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/media?parent=1440"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/categories?post=1440"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/tags?post=1440"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} Check with whom you work <\/ h3><\/h3>\n
![\"\"](\"https:\/\/demensdeum.com\/blog\/wp-content\/uploads\/2018\/08\/NOTSUREIF.jpg\")
<\/p>\n![\"\"](\"https:\/\/demensdeum.com\/blog\/wp-content\/uploads\/2018\/08\/apicalls.png\")
<\/p>\n Determine who is in life <\/ h3><\/h3>\n
\n sdl_gl_seettrtribute (sdl_gl_context_major_version, 3 <\/span>);
\nSDL_GL_SETTRIBUTE (SDL_GL_CONTEXT_MINOR_VERSION, 2 <\/span>);
\nSDL_GL_SETTRIBUTE (SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
\n<\/ Pre>\n<\/div>\n
\nBecause the context of Opengl 3.2 must require the presence of VAO buffer <\/strong>, without which 99% of graphic drivers do not work. Add it easy:
\n <\/p>\n
\n Glgenvertexarrays ( 1 <\/span>, & <\/span> vao);
\nGLBINDVERTEXARAY (VAO);
\n<\/ Pre>\n<\/div>\n Do not sleep, freeze <\/ h3><\/h3>\n
\nhttps:\/\/stackoverflow.com\/questions\/38411515\/sdl2-opengl-window-appears-semi-transparent-sometimes<\/a><\/p>\n
\nhttps:\/\/gitlab.com\/demensdeum\/FSGLtests\/blob\/master\/renderModelTest\/<\/a><\/p>\n Talk to the driver <\/ h3><\/h3>\n
\nAn example of initialization can be taken here:
\nhttps:\/\/github.com\/rock-core\/gui-vizkit3d\/blob\/master\/src\/EnableGLDebugOperation.cpp<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"