c++ - Qt 5.3. QWidget direct painting with OpenGL -

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good day. there ways paint qwidget-based window without qpainter. try use raw opengl drawing following code:

1) main function:

int main(int argc, char* argv[]) {     qapplication app(argc, argv);     glwindow* window = new glwindow;     window->setminimumsize(200, 200);     window->initializeglcontext();     window->show();     return app.exec();  }

glwindow inhereted qmainwindow. use glew library in order work opengl. below simplified version of code without error handling , stupid program flow.

namespace {     glfloat vertices[] = {         0.0f, 0.5f,         0.5f, -0.5f,         -0.5f, -0.5f     };     const char* vertexshadersource =         "in vec2 position;"          "void main() {"          "gl_position = vec4(position, 0.0, 1.0); }";      const char* fragmentshadersource =         "out vec4 outcolor;"         "void main() {"         "outcolor = vec4(1.0, 0.0, 0.0, 1.0); }"; }  glwindow::glwindow() {     setattribute(qt::wa_paintonscreen, true); }  void glwindow::initializeglcontext() {      pixelformatdescriptor pfd = {         sizeof(pixelformatdescriptor), 1,         pfd_draw_to_window | pfd_support_opengl | pfd_doublebuffer,         pfd_type_rgba, 32, 0, 0, 0, 0, 0, 0,         0, 0, 0, 0, 0, 0, 0,         24, 8, 0,         pfd_main_plane, 0, 0, 0, 0 };      hdc hdc = getdc((hwnd)winid());      int windowpixelformat = choosepixelformat(hdc, &pfd);     setpixelformat(hdc, windowpixelformat, &pfd);      hglrc hglrc = wglcreatecontext(hdc);     wglmakecurrent(hdc, hglrc); }  qpaintengine* glwindow::paintengine() const { return 0; }  void glwindow::paintevent(qpaintevent *) {      glewinit();      gluint vao;     glgenvertexarrays(1, &vao);     glbindvertexarray(vao);      gluint vbo;     glgenbuffers(1, &vbo);     glbindbuffer(gl_array_buffer, vbo);     glbufferdata(gl_array_buffer, sizeof(vertices), vertices, gl_static_draw);      gluint vertexshader = glcreateshader(gl_vertex_shader);     glshadersource(vertexshader, 1, &vertexshadersource, null);     glcompileshader(vertexshader);      gluint fragmentshader = glcreateshader(gl_fragment_shader);     glshadersource(fragmentshader, 1, &fragmentshadersource, null);     glcompileshader(fragmentshader);      gluint shaderprogram = glcreateprogram();     glattachshader(shaderprogram, vertexshader);     glattachshader(shaderprogram, fragmentshader);     gllinkprogram(shaderprogram);     gluseprogram(shaderprogram);      glint posattrib = glgetattriblocation(shaderprogram, "position");     glenablevertexattribarray(posattrib);     glvertexattribpointer(posattrib, 2, gl_float, gl_false, 0, 0);      glclearcolor(0.0f, 0.0f, 0.0f, 1.0f);     glclear(gl_color_buffer_bit);      gldrawarrays(gl_triangles, 0, 3);      swapbuffers(getdc((hwnd)winid())); }

after program execution have black screen without triangle. i'm novice in qt , if have suggestions going wrong, please share them me.

best regards.

you should use baseclass qglwidget , override paintgl instead.


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