c++ - Weird Result with Depth Test -
i'm having problem when enable gl_depth_test when rendering objects, here's happens:
gl_cull_face disable on one.
it happens perspective view! have , idea of what's happening?
i'm using qt 4.8 this.
of course, if disable depth test, looks fine, objects overlays in wrong way, expected.
update
i create projection matrix this:
projectionmatrix.settoidentity(); projectionmatrix.perspective(45, float(width) / float(height), 0, 20.0); where width , height related viewport size.
here's code draw scene:
void glwidget::paintgl() { glclearcolor(0.4765625, 0.54296875, 0.6171875, 1.0); glclear(gl_color_buffer_bit | gl_depth_buffer_bit); editor->setuniformvalue("projectmatrix", controller->getprojectionmatrix()); editor->setuniformvalue("viewmatrix", controller->getviewmatrix()); /** dibujemos los grids **/ gldisable(gl_depth_test); gldisable(gl_cull_face); (int i=0; i<3; i++) { if ((front && i==1) || (side && i==2) || (i==0)) { editor->setuniformvalue("modelmatrix", objects.at(i).modelmatrix); editor->setuniformvalue("normalmatrix", objects[i].getnormalmatrix()); editor->setuniformvalue("texture", textureon); glenableclientstate(gl_vertex_array); editor->enableattributearray("vertices"); objects[i].vertexbuffer->bind(); editor->setattributebuffer("vertices", gl_float, 0, 3); gldisableclientstate(gl_vertex_array); glenableclientstate(gl_texture_coord_array); editor->enableattributearray("texuv"); objects[i].uvbuffer->bind(); editor->setattributebuffer ("texuv", gl_float, 0, 2); gldisableclientstate(gl_texture_coord_array); glenableclientstate(gl_normal_array); editor->enableattributearray("normals"); objects[i].normalbuffer->bind(); editor->setattributebuffer ("normals", gl_float, 0, 3); gldisableclientstate(gl_normal_array); objects[i].elementbuffer->bind(); glbindtexture(gl_texture_2d, objects[i].texture); gldrawelements(gl_triangles, objects[i].indices.size(), gl_unsigned_short, (void*)0); } } /** ahora para las operaciones especificas de cada objeto **/ glenable(gl_depth_test); //glenable(gl_cull_face); (int i=3; i<objects.size(); i++) { //objects[i].modelmatrix.scale(1.0, 1.0, 1.0); //objects[i].modelmatrix.rotate(1.0, 0.0, 1.0, 0.0); editor->setuniformvalue("modelmatrix", objects.at(i).modelmatrix); editor->setuniformvalue("normalmatrix", objects[i].getnormalmatrix()); editor->setuniformvalue("texture", textureoff); editor->setuniformvalue("diffusecolor", objects.at(i).diffusecolor); editor->setuniformvalue("shininess", objects.at(i).shininess); editor->setuniformvalue("hardness", objects.at(i).hardness); editor->setuniformvalue("lpos1", objects.at(i).l1pos); editor->setuniformvalue("lpos2", objects.at(i).l2pos); editor->setuniformvalue("lpos3", objects.at(i).l3pos); editor->setuniformvalue("lpos4", objects.at(i).l4pos); glenableclientstate(gl_vertex_array); editor->enableattributearray("vertices"); objects[i].vertexbuffer->bind(); editor->setattributebuffer("vertices", gl_float, 0, 3); gldisableclientstate(gl_vertex_array); glenableclientstate(gl_normal_array); editor->enableattributearray("normals"); objects[i].normalbuffer->bind(); editor->setattributebuffer ("normals", gl_float, 0, 3); gldisableclientstate(gl_normal_array); objects[i].elementbuffer->bind(); gldrawelements(gl_triangles, objects[i].indices.size(), gl_unsigned_short, (void*)0); } } in short lines, first draw grids according camera facing, in order give functionallity blender's. then, draw objects. i'm using indexed vbos achieve this.
i draw them in ccw, i'm 99% sure triangles being passed opengl in way.
the near value of [edit perspective] projection matrix zero. results in depth values equal 1 after perspective divide (.xyz/.w). @raxvan had right idea. try this...
projectionmatrix.perspective(45, float(width) / float(height), 0.01, 20.0); of course large scenes want large depth range, if make big wind z-fighting fragments @ different distances still have same depth values , ever gets rasterized first wins (which seems problem you're having). try keep depth range no bigger factor of 10,000 apart.
if have large scenes, might need @ alternative methods. start, use higher precision depth buffer. if that's not enough, maybe use 2 projection matrices , split scene near , far objects. causes issues if objects intersect boundary. here's related links...
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