c++ - Vertex Buffer Objects Open GL -

-

i new open gl , trying build non deprecated code. can't grasp vbo. got far, can please explain i'm supposed doing. also, have opengl programming guide, if can point out pages read helpful well.

#include <gl/glew.h> #include <gl/freeglut.h>   gluint id[2]; glfloat positiondata[][2] ={{50,50},{100,50},{50,100}, {100,50}, {100, 100}, {50, 100}}; glfloat colors[][3] = {{0.1, 0.2, 0.3},{0.1, 0.2, 0.3},{0.1, 0.2, 0.3},{0.1, 0.2, 0.3},{0.1, 0.2, 0.3}};  void init(){     glewinit();     glclearcolor(1.0, 1.0, 1.0, 0.0); }  void display(){     glclear(gl_color_buffer_bit);     glshademodel(gl_flat);     glgenbuffers(2, id);     glbindbuffer(gl_array_buffer, id[0]);     glbufferdata(gl_array_buffer, sizeof(positiondata), positiondata, gl_static_draw);     glenableclientstate(gl_vertex_array);     glvertexattribpointer(0, 3, gl_float, gl_false, 0, 0);     glenablevertexattribarray(0);     glbindbuffer(gl_array_buffer, id[1]);     glbufferdata(gl_array_buffer, sizeof(colors), colors, gl_static_draw);     glenableclientstate(gl_color_array);     glvertexattribpointer(1, 3, gl_float, gl_false, 0, 0);     glenablevertexattribarray(1);      gldrawarrays(gl_triangles, 0, 12);      gldisablevertexattribarray(0);     gldisablevertexattribarray(1);     gldeletebuffers(2, id);     glflush(); }  void reshape(int w, int h){     glviewport(0,0, (glsizei) w, (glsizei) h);     glmatrixmode(gl_projection);     glloadidentity();     gluortho2d(0.0f, (gldouble) w, 0.0f, (gldouble) h); }  int main(int argc, char *argv[]){     glutinit(&argc, argv);     glutinitdisplaymode(glut_single | glut_rgb);     glutinitwindowsize(500, 500);     glutinitwindowposition(100, 100);     glutcreatewindow("i don't vbos");     init();     glutdisplayfunc(display);     glutreshapefunc(reshape);     glutmainloop();     return 0; }

i did quick on code, 1 thing stood out: you're missing point of vbos. in each draw call you're creating vbo objects, upload data, try draw them (it won't work, because shaders giving vertex attributes sense misssing) , delete them.

the whole point of vbo upload geometry data gl object once , refer it's abstract object id handle , index arrays, 1 place in buffer object.

but there's else screwed in code, setting projection matrix in reshape callback. 1 thing, in opengl-3 core don't have built-in matrices anymore. it's shader uniforms. , set matrices on demand in rendering handler.

i think should write definitive opengl-3 core tutorial, demonstrating proper idioms.


Comments

Post a Comment

Popular posts from this blog

Javascript line number mapping -

-
magically formatted comments change reported line number of javascript errors in browsers; this: //@line n "f" n line number , f file name. unfortunately, //@line appears ungoogleable. know there documentation on feature, , browsers support it? (i found references here , here .) from can find available in mozilla based browsers. it using js_setoptions command can turn these options on or off depending on values passed. https://developer.mozilla.org/en/js_setoptions
Read more

c# - Is it possible to remove an existing registration from Autofac container builder? -

-
something along lines: builder.registertype<mytype>().as<itype>(); builder.registertype<mytype2>().as<itype>(); builder.deregistertype<mytype>().as<itype>() var container = builder.build(); var types = container.resolve<ienumerable<itype>>(); assert.istrue(types.count == 1); assert.istrue(types[0].gettype == typeof(mytype2)); scenario: go through bunch of assemblies , go register types want make sure have 1 implementation of given type. need before create container. track on own nice if autofac me bit. this cannot done directly using containerbuilder , unless start on new one. mind you, having first built container should able construct new container filtering away unwanted types , reusing registrations first container. this: ... var container = builder.build(); builder = new containerbuilder(); var components = container.componentregistry.registrations .where(cr => cr.activator.limittype != typ...
Read more

php - Mysql PK and FK char(36) vs int(10) -

-
i have read mysql can handle indexes , searches better if tables keys integers rather char(36) uuid's. is worth converting int(10)? note: use 1 server , have have plans use multiple databases concurrently therefore removing 1 of big reasons using uuid. our tables innodb if makes difference. thanks in advance. usually rdbms can handle integer keys pk more efficient, other datatypes. reason how build index column, yes: long dont require string (or other typed) keys, should use integers. however: char(36) , int(10) far away being equal, because int(10) much smaller, char(36). dont know, if require many different keys, should keep in mind. update, complete last paragraph: int(10) 32-bit, char(36) 36 - ^byte^ (= 288-bit). not mean, int consumes less space, means, char(36) has 4 times more different keys.
Read more