c++ - Drawing a Texture to the Screen -

i attempting learn directx, , feeling quite overwhelmed. can tell me why not working? image not display screen. window black. trying follow along tutorial this, , code had.

#include <windows.h> #include <d3d9.h> #include <d3dx9tex.h>  lpdirect3d9 direct3d = null; lpdirect3ddevice9 direct3ddevice = null; idirect3dtexture9* texture;  lresult winapi wndproc(hwnd hwnd, uint msg, wparam wparam, lparam lparam); idirect3dtexture9 *loadtexture(wchar_t *filename); void blitd3d (idirect3dtexture9 *texture, rect *rdest, d3dcolor vertexcolour, float rotate);  int winapi winmain(hinstance hinstance, hinstance hprevinstance, lpstr lpcmdline, int nshow) { msg msg;  wndclassex wc = {sizeof(wndclassex), cs_vredraw|cs_hredraw|cs_owndc,     wndproc, 0, 0, hinstance, null, null, (hbrush)(color_window+1),     null, l"dx9_tutorial1_class", null}; registerclassex(&wc);  hwnd hmainwnd = createwindow(l"dx9_tutorial1_class",     l"directx 9 bare bones tutorial 1",     ws_overlappedwindow, 100, 100, 300, 300,     null, null, hinstance, null);  direct3d = direct3dcreate9(d3d_sdk_version); d3dpresent_parameters presentparams; memset(&presentparams, 0, sizeof(d3dpresent_parameters));  presentparams.windowed = true; presentparams.swapeffect = d3dswapeffect_discard; direct3d->createdevice(d3dadapter_default, d3ddevtype_hal, hmainwnd,     d3dcreate_software_vertexprocessing, &presentparams, &direct3ddevice);  direct3ddevice->setrenderstate(d3drs_lighting, false); direct3ddevice->setrenderstate(d3drs_alphablendenable, true); direct3ddevice->setrenderstate(d3drs_srcblend, d3dblend_srcalpha); direct3ddevice->setrenderstate(d3drs_destblend, d3dblend_invsrcalpha); direct3ddevice->settexturestagestate(0, d3dtss_alphaop, d3dtop_modulate);  texture = loadtexture(l"ash.png");  showwindow(hmainwnd, nshow); updatewindow(hmainwnd);  while (getmessage(&msg, null, 0, 0)) {     translatemessage(&msg);     dispatchmessage(&msg); }  direct3ddevice->release(); direct3d->release();  return 0; }  lresult winapi wndproc(hwnd hwnd, uint msg, wparam wparam, lparam lparam) { switch (msg) {     case wm_destroy:         postquitmessage(0);         return 0;      case wm_paint:         rect* rect = new rect;         rect->left = 10;         rect->top = 10;         rect->bottom = 60;         rect->right = 60;          direct3ddevice->clear(0, null, d3dclear_target, d3dcolor_xrgb(0, 0, 0),             1.0f, 0);          direct3ddevice->beginscene();          blitd3d(texture, rect, d3dcolor_argb(1, 1, 1,1), 0);          direct3ddevice->endscene();          direct3ddevice->present(null, null, null, null);          validaterect(hwnd, null);          return 0; }  return (defwindowproc(hwnd, msg, wparam, lparam)); }  //load texture file d3dx //supported formats: bmp, ppm, dds, jpg, png, tga, dib idirect3dtexture9 *loadtexture(wchar_t *filename) { idirect3dtexture9 *d3dtexture;  //use magenta colourkey d3dcolor colorkey = 0xffff00ff;  // load image file if (failed(d3dxcreatetexturefromfileex (direct3ddevice, filename, 0, 0, 1, 0,     d3dfmt_a8r8g8b8, d3dpool_managed, d3dx_filter_none, d3dx_default,     colorkey, null, null, &d3dtexture))) {     return null; }  //return newly made texture return d3dtexture; }  //draw textured quad on back-buffer void blitd3d (idirect3dtexture9 *texture, rect *rdest, d3dcolor vertexcolour, float rotate) { const dword d3dfvf_tlvertex = d3dfvf_xyzrhw | d3dfvf_diffuse | d3dfvf_tex1;  struct tlvertex {     float x, y, z, rhw;     d3dcolor color;     float u;     float v; };  idirect3dvertexbuffer9* vertexbuffer;  // set vertex shader. direct3ddevice->setvertexshader(null); direct3ddevice->setfvf(d3dfvf_tlvertex);  // create vertex buffer. direct3ddevice->createvertexbuffer(sizeof(tlvertex) * 4, null,     d3dfvf_tlvertex, d3dpool_managed, &vertexbuffer, null); direct3ddevice->setstreamsource(0, vertexbuffer, 0, sizeof(tlvertex));  tlvertex* vertices;  //lock vertex buffer vertexbuffer->lock(0, 0, (void**)&vertices, null);  //setup vertices //a -0.5f modifier applied vertex coordinates match texture //and screen coords. drivers may compensate //automatically, on others texture alignment errors introduced //more information on can found in direct3d 9 documentation vertices[0].color = vertexcolour; vertices[0].x = (float) rdest->left - 0.5f; vertices[0].y = (float) rdest->top - 0.5f; vertices[0].z = 0.0f; vertices[0].rhw = 1.0f; vertices[0].u = 0.0f; vertices[0].v = 0.0f;  vertices[1].color = vertexcolour; vertices[1].x = (float) rdest->right - 0.5f; vertices[1].y = (float) rdest->top - 0.5f; vertices[1].z = 0.0f; vertices[1].rhw = 1.0f; vertices[1].u = 1.0f; vertices[1].v = 0.0f;  vertices[2].color = vertexcolour; vertices[2].x = (float) rdest->right - 0.5f; vertices[2].y = (float) rdest->bottom - 0.5f; vertices[2].z = 0.0f; vertices[2].rhw = 1.0f; vertices[2].u = 1.0f; vertices[2].v = 1.0f;  vertices[3].color = vertexcolour; vertices[3].x = (float) rdest->left - 0.5f; vertices[3].y = (float) rdest->bottom - 0.5f; vertices[3].z = 0.0f; vertices[3].rhw = 1.0f; vertices[3].u = 0.0f; vertices[3].v = 1.0f;  //unlock vertex buffer vertexbuffer->unlock();  //set texture direct3ddevice->settexture (0, texture);  //draw image direct3ddevice->drawprimitive (d3dpt_trianglefan, 0, 2); } 

you have several issues prevent app proper rendering.

• your code hairy mess. every function whatever wants. impossible read , find bugs. instead make number of functions, doing concrete tasks, separating responsibilities, can focus (debug, improve) @ 1 task time.

• no error checking. naver find bug if (1) dont know happened, (2) happened. after every single function call, must check possible errors. directx api makes easy: can @ hresult variable, returned function, "decode" it, , in case of fail change program flow handle error or make warning. see code below.

• use d3dfmt_unknown in d3dxcreatetexturefromfileex if not sure format image file has:

  d3dxcreatetexturefromfileex (direct3ddevice, filename, 0, 0, 0, 0, d3dfmt_unknown, d3dpool_managed, d3dx_filter_none, d3dx_default, colorkey, 0, 0, &d3dtexture)

• never use wm_paint trigger rendering. app rendering 1 frame. instead, put rendering in main loop.

full source long , formatting little pain, i've uploaded pastebin: link (you must add linker input options dxerr.lib dxsdk or here )

further reading:

• msdn d3dxcreatetexturefromfileex
• error handling: hresult, common hresult values
• directx 9 tutorials: chad vernon, drunken hyena, directxtutorial.com