general: Don't use NULL where not appropriate

panda/src/dxgsg9/dxTextureContext9.cxx

@@ -1935,7 +1935,7 @@ fill_d3d_texture_pixels(DXScreenData &scrn, bool compress_texture) {
                 scaled *= 255;
                 color = D3DCOLOR_RGBA((int)scaled[0], (int)scaled[1], (int)scaled[2], (int)scaled[3]);
                 flags = D3DCLEAR_TARGET;
-                if (device -> Clear (NULL, NULL, flags, color, 0.0f, 0) == D3D_OK) {
+                if (device -> Clear (0, NULL, flags, color, 0.0f, 0) == D3D_OK) {
                 }
               }
 

panda/src/express/virtualFileMountSystem.cxx

@@ -385,7 +385,7 @@ atomic_compare_and_exchange_contents(const Filename &file, string &orig_contents
   // First ensure that the file exists to validate its case.
   if (VirtualFileSystem::get_global_ptr()->vfs_case_sensitive) {
     if (!has_file(file)) {
-      return NULL;
+      return false;
     }
   }
 #endif  // WIN32
@@ -402,7 +402,7 @@ atomic_read_contents(const Filename &file, string &contents) const {
   // First ensure that the file exists to validate its case.
   if (VirtualFileSystem::get_global_ptr()->vfs_case_sensitive) {
     if (!has_file(file)) {
-      return NULL;
+      return false;
     }
   }
 #endif  // WIN32

panda/src/gobj/vertexDataSaveFile.cxx

@@ -306,7 +306,7 @@ read_data(unsigned char *data, size_t size, VertexDataSaveBlock *block) {
         << "Error reading " << size
         << " bytes from save file, windows error code 0x" << hex
         << error << dec << ".\n";
-      return NULL;
+      return false;
     }
     success = GetOverlappedResult(_handle, &overlapped, &bytes_read, false);
   }

panda/src/movies/microphoneAudioDS.cxx

@@ -146,7 +146,7 @@ find_all_microphones_ds() {
         format.nBlockAlign = 2 * chan;
         format.wBitsPerSample = 16;
         format.cbSize = 0;
-        stat = waveInOpen(NULL, i, &format, NULL, NULL, WAVE_FORMAT_QUERY);
+        stat = waveInOpen(NULL, i, &format, 0, 0, WAVE_FORMAT_QUERY);
         if (stat == MMSYSERR_NOERROR) {
           PT(MicrophoneAudioDS) p = new MicrophoneAudioDS();
           ostringstream name;
@@ -248,7 +248,7 @@ open() {
   format.cbSize = 0;
 
   HWAVEIN hwav;
-  MMRESULT stat = waveInOpen(&hwav, _device_id, &format, NULL, NULL, CALLBACK_NULL);
+  MMRESULT stat = waveInOpen(&hwav, _device_id, &format, 0, 0, CALLBACK_NULL);
 
   if (stat != MMSYSERR_NOERROR) {
     delete_buffers(buffers);

panda/src/wgldisplay/wglGraphicsStateGuardian.cxx

@@ -594,7 +594,7 @@ make_context(HDC hdc) {
     // what kind of OpenGL context we would like.
     int attrib_list[32];
     int n = 0;
-    attrib_list[0] = NULL;
+    attrib_list[0] = 0;
 
     if (gl_version.get_num_words() > 0) {
       attrib_list[n++] = WGL_CONTEXT_MAJOR_VERSION_ARB;
@@ -612,7 +612,7 @@ make_context(HDC hdc) {
     attrib_list[n++] = WGL_CONTEXT_PROFILE_MASK_ARB;
     attrib_list[n++] = WGL_CONTEXT_CORE_PROFILE_BIT_ARB;
 #endif
-    attrib_list[n] = NULL;
+    attrib_list[n] = 0;
 
     _context = _wglCreateContextAttribsARB(hdc, 0, attrib_list);
   } else {

panda/src/windisplay/winGraphicsWindow.cxx

@@ -1870,7 +1870,7 @@ window_proc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
             lptstr = (char *) GlobalLock(hglb);
             if (lptstr != NULL)  {
               char *pChar;
-              for (pChar=lptstr; *pChar!=NULL; pChar++) {
+              for (pChar=lptstr; *pChar; pChar++) {
                 _input_devices[0].keystroke((uchar)*pChar);
               }
               GlobalUnlock(hglb);
@@ -2159,12 +2159,12 @@ update_cursor_window(WinGraphicsWindow *to_window) {
     // We are leaving a graphics window; we should restore the Win2000
     // effects.
     if (_got_saved_params) {
-      SystemParametersInfo(SPI_SETMOUSETRAILS, NULL,
-                           (PVOID)_saved_mouse_trails, NULL);
-      SystemParametersInfo(SPI_SETCURSORSHADOW, NULL,
-                           (PVOID)_saved_cursor_shadow, NULL);
-      SystemParametersInfo(SPI_SETMOUSEVANISH, NULL,
-                           (PVOID)_saved_mouse_vanish, NULL);
+      SystemParametersInfo(SPI_SETMOUSETRAILS, 0,
+                           (PVOID)_saved_mouse_trails, 0);
+      SystemParametersInfo(SPI_SETCURSORSHADOW, 0,
+                           (PVOID)_saved_cursor_shadow, 0);
+      SystemParametersInfo(SPI_SETMOUSEVANISH, 0,
+                           (PVOID)_saved_mouse_vanish, 0);
       _got_saved_params = false;
     }
 
@@ -2178,17 +2178,17 @@ update_cursor_window(WinGraphicsWindow *to_window) {
     // These parameters are only defined for Win2000XP, but they should just
     // cause a silent error on earlier OS's, which is OK.
     if (!_got_saved_params) {
-      SystemParametersInfo(SPI_GETMOUSETRAILS, NULL,
-                           &_saved_mouse_trails, NULL);
-      SystemParametersInfo(SPI_GETCURSORSHADOW, NULL,
-                           &_saved_cursor_shadow, NULL);
-      SystemParametersInfo(SPI_GETMOUSEVANISH, NULL,
-                           &_saved_mouse_vanish, NULL);
+      SystemParametersInfo(SPI_GETMOUSETRAILS, 0,
+                           &_saved_mouse_trails, 0);
+      SystemParametersInfo(SPI_GETCURSORSHADOW, 0,
+                           &_saved_cursor_shadow, 0);
+      SystemParametersInfo(SPI_GETMOUSEVANISH, 0,
+                           &_saved_mouse_vanish, 0);
       _got_saved_params = true;
 
-      SystemParametersInfo(SPI_SETMOUSETRAILS, NULL, (PVOID)0, NULL);
-      SystemParametersInfo(SPI_SETCURSORSHADOW, NULL, (PVOID)false, NULL);
-      SystemParametersInfo(SPI_SETMOUSEVANISH, NULL, (PVOID)false, NULL);
+      SystemParametersInfo(SPI_SETMOUSETRAILS, 0, (PVOID)0, 0);
+      SystemParametersInfo(SPI_SETCURSORSHADOW, 0, (PVOID)false, 0);
+      SystemParametersInfo(SPI_SETMOUSEVANISH, 0, (PVOID)false, 0);
     }
 
     SetCursor(to_window->_cursor);