c++ - How to fill the deph buffer in OpenGL 1 with a depth texture? -

i separate moveable 3d object , non moveable 3d. can generate 2 textures non moveables : background color texture , background depth texture . have no problem. values ok both. check value gray gradient texture depth.

and write / fill color buffer , depth buffer in opengl texture depth doesn't work (the color buffer fine on screen).

my goal never recompute non movable 3d objects when camera doesn't move.

(rem : depth buffer bits size in 16 bits)

this code generate depth texture :

u16 m_backgrounddepthbuffer[4096 * 4096]; // it's member of class  glreadpixels(0,0, width(), height(), gl_depth_component, gl_unsigned_short, (void*)m_backgrounddepthbuffer);  // allocate gpu-memory depth-texture. gldeletetextures(1, &m_backgrounddepthtextureid); glgentextures(1, &m_backgrounddepthtextureid); glbindtexture(gl_texture_2d, m_backgrounddepthtextureid); gltexparameteri(gl_texture_2d, gl_texture_min_filter, gl_nearest); gltexparameteri(gl_texture_2d, gl_texture_mag_filter, gl_nearest); glteximage2d(gl_texture_2d, 0, gl_depth_component16,             width(), height(), 0, gl_depth_component, gl_unsigned_short, m_backgrounddepthbuffer); 

this code filling color buffer :

void application::render() {     glenable(gl_depth_test);     gldepthfunc(gl_less);      glclear(gl_depth_buffer_bit|gl_color_buffer_bit);       // render background     render::renderimage(m_backgroundtextureid, 0,0, width(), height());      // debug     // render::renderimage(m_backgrounddepthgraytextureid, 0,0, width(), height());       // how fill depth buffer : it's work slow     gldrawpixels(width(), height(), gl_depth_component, gl_unsigned_short, (glvoid*) m_backgrounddepthbuffer); //       // doesn't work     // render::renderdepth(m_backgrounddepthtextureid, 0,0, width(), height());  } 

this render::renderimage() : works

void render::renderimage(u32 tex, int x, int y, int w, int h, float anchorx, float anchory) {     glclear(gl_depth_buffer_bit);      glboolean depth = glisenabled(gl_depth_test);     if (depth)         gldisable(gl_depth_test);      glmatrixmode(gl_projection);     glpushmatrix();     glloadidentity();     gluortho2d(0, s_width, s_height, 0);      glmatrixmode(gl_modelview);     glpushmatrix();     glloadidentity();      glcolor3ub(255, 255, 255);      glenable(gl_texture_2d);     glbindtexture(gl_texture_2d, tex);      glenableclientstate(gl_vertex_array);     glenableclientstate(gl_texture_coord_array);     gldisableclientstate(gl_color_array);      x -= (int)(anchorx * w);     y -= (int)(anchory * h);      gvertices[0] = vector3f(x, y, 0);     gvertices[1] = vector3f(x + w - 1, y, 0);     gvertices[2] = vector3f(x + w - 1, y + h - 1, 0);     gvertices[3] = vector3f(x, y + h - 1, 0);      gtexcoords[0] = vector2f(0, 1);     gtexcoords[1] = vector2f(1, 1);     gtexcoords[2] = vector2f(1, 0);     gtexcoords[3] = vector2f(0, 0);      gindexes[0] = 2;     gindexes[1] = 1;     gindexes[2] = 0;      gindexes[3] = 0;     gindexes[4] = 3;     gindexes[5] = 2;      glvertexpointer(3, gl_float, 0, gvertices);      gltexcoordpointer(2, gl_float, 0, gtexcoords);     gldrawelements(gl_triangles, 3 * 2, gl_unsigned_short, gindexes);      gldisable(gl_texture_2d);       glpopmatrix();      glmatrixmode(gl_projection);     glpopmatrix();     glmatrixmode(gl_modelview);      if (depth)         glenable(gl_depth_test); } 

this render::renderdepth() : doesn't work / have texture depth = 0.0f instead use depth of each texel. want change depth buffer , nothing color buffer render::renderdepth() similar render::renderimage() : render 2 triangles

void render::renderdepth(u32 tex, int x, int y, int w, int h, float anchorx, float anchory) {     glclear(gl_depth_buffer_bit);       /*gltexparameteri(gl_texture_2d_array, gl_texture_compare_mode, gl_compare_ref_depth_to_texture_ext);     gltexparameteri(gl_texture_2d_array, gl_texture_compare_func, gl_always);     gltexparameteri(gl_texture_2d_array, gl_depth_texture_mode, gl_alpha); */     glboolean depth = glisenabled(gl_depth_test);     //if (depth)     glenable(gl_depth_test);      glmatrixmode(gl_projection);     glpushmatrix();     glloadidentity();     gluortho2d(0, s_width, s_height, 0);      glmatrixmode(gl_modelview);     glpushmatrix();     glloadidentity();      glcolor3ub(255, 255, 255);      glenable(gl_texture_2d);     glbindtexture(gl_texture_2d, tex);      glenableclientstate(gl_vertex_array);     glenableclientstate(gl_texture_coord_array);     gldisableclientstate(gl_color_array);      x -= (int)(anchorx * w);     y -= (int)(anchory * h);      gvertices[0] = vector3f(x, y, 0.0);     gvertices[1] = vector3f(x + w - 1, y, 0.0);     gvertices[2] = vector3f(x + w - 1, y + h - 1, 0.0);     gvertices[3] = vector3f(x, y + h - 1, 0.0);      gtexcoords[0] = vector2f(0, 1);     gtexcoords[1] = vector2f(1, 1);     gtexcoords[2] = vector2f(1, 0);     gtexcoords[3] = vector2f(0, 0);      gindexes[0] = 2;     gindexes[1] = 1;     gindexes[2] = 0;      gindexes[3] = 0;     gindexes[4] = 3;     gindexes[5] = 2;      glvertexpointer(3, gl_float, 0, gvertices);     gltexcoordpointer(2, gl_float, 0, gtexcoords);     gldrawelements(gl_triangles, 3 * 2, gl_unsigned_short, gindexes);      gldisable(gl_texture_2d);       glpopmatrix();      glmatrixmode(gl_projection);     glpopmatrix();     glmatrixmode(gl_modelview);  }