Create an image or bitmap with a different depth?

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WLGfx

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Posted: 11th Aug 2011 00:16

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Is this possible? I only want to create a 4 colour bitmap so that I can overlay a map image on the screen.

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Mistrel

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Posted: 11th Aug 2011 00:58 Edited at: 11th Aug 2011 01:01

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dbCreateMemblock + dbGetMemblockPtr + dbCreateMemblockFromBitmap/Image will do what you want.

By asking to create a 4 color bitmap, if you want to create an 8-bit bitmap with a custom color table of only 4 colors, see here:

http://en.wikipedia.org/wiki/BMP_file_format
http://fortunecity.com/skyscraper/windows/364/bmpffrmt.html

Even if you only want to use 4 colors, there is little reason to use an 8-bit bitmap unless you want to use the color table specifically; or for space reasons. DBP might not even support reading this type of image format if you want to convert it to a usable ID.

Alternatively, you can use Win32 to create a bitmap with GDI+, draw to it, then get a pointer to the data with GetDIBits and then use dbCreateMemblockFromImage to get an image out of it.

Or.. use GDI+ to make your bitmap and then draw it to the screen by writing to the backbuffer.

Or.. create and write to a bitmap with ImageMagick, (a good alternative to GDI+) and do the same.

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WLGfx

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Posted: 11th Aug 2011 03:00

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GDI+ ? Something new to me.

I'm actually after just drawing a portion of the image using colour 0 as a transparency and show it as an overlay map view. Grabbing and pasting images would only slow down the program, so if I could do it directly after everything has been rendered that would be great.

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Mistrel

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Posted: 11th Aug 2011 05:33 Edited at: 11th Aug 2011 06:33

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I'm still not sure what it is you're asking. Do you want chroma keying?

In DarkGDK it's: dbSetImageColorKey. In PureGDK it's: dbSetImageChromaKey.

dbLoadImage with a 'textureFlag' of 0 will support stretching, filtering, and chroma keying. A flag of 1 will support just chroma keying.

Is this what you want?

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Mistrel

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Posted: 11th Aug 2011 06:14 Edited at: 11th Aug 2011 06:32

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Chroma keying seems to work with ok with dbPastImage(), sprites, and 3d objects. Is this what you want?

Example with paste image:

#include <puregdk/core/puregdk.h>
#include <puregdk/initPureGDK.h>
#include <puregdk/simpleWindow.h>

#include <windows.h>

using namespace std;

int __stdcall WinMain(HINSTANCE, HINSTANCE, LPSTR, int) {
   int screenWidth = 640;
   int screenHeight = 480;
   
   if (!initPureGDK("gdkengine.dll"))
      return 1;
   
   HWND hWnd = openWindow(0, 0, screenWidth, screenHeight,
      "PureGDK - Game Developer's Toolkit",  WS_OVERLAPPED | WS_CLIPSIBLINGS |
      WS_CAPTION | WS_SYSMENU | WS_CLIPCHILDREN, true);
   
   dbOpenScreen(hWnd, 0, 0, screenWidth, screenHeight);
   
   ShowWindow(hWnd, SW_SHOW);
   
   dbAutoCamOff();
   
   // Must be called before image is loaded
   dbSetImageChromaKey(255, 0, 255);
   
   // Get circle
   dbInk(dbRGB(255, 0, 255), 0);
   dbBox(0, 0, 320, 320);
   dbInk(dbRGB(0, 0, 0), 0);
   dbCircle(320/2, 320/2, 150);
   int circleImageId = dbGetImage(0, 0, 320, 320, 0);
   
   // Set the background color
   dbClearScreen(dbRGB(133, 194, 122));
   
   // Paste the image, black is transparent
   dbPasteImage(circleImageId, 320/2, 320/4, 1);
   
   do {
      dbSync();
   }
   while (waitWindowEvent(1) != WM_CLOSE);
   
   dbCloseScreen();
   
   return 0;
}

+ Code Snippet

#include <puregdk/core/puregdk.h>
#include <puregdk/initPureGDK.h>
#include <puregdk/simpleWindow.h>

#include <windows.h>

using namespace std;

int __stdcall WinMain(HINSTANCE, HINSTANCE, LPSTR, int) {
   int screenWidth = 640;
   int screenHeight = 480;
   
   if (!initPureGDK("gdkengine.dll"))
      return 1;
   
   HWND hWnd = openWindow(0, 0, screenWidth, screenHeight,
      "PureGDK - Game Developer's Toolkit",  WS_OVERLAPPED | WS_CLIPSIBLINGS |
      WS_CAPTION | WS_SYSMENU | WS_CLIPCHILDREN, true);
   
   dbOpenScreen(hWnd, 0, 0, screenWidth, screenHeight);
   
   ShowWindow(hWnd, SW_SHOW);
   
   dbAutoCamOff();
   
   // Must be called before image is loaded
   dbSetImageChromaKey(255, 0, 255);
   
   // Get circle
   dbInk(dbRGB(255, 0, 255), 0);
   dbBox(0, 0, 320, 320);
   dbInk(dbRGB(0, 0, 0), 0);
   dbCircle(320/2, 320/2, 150);
   int circleImageId = dbGetImage(0, 0, 320, 320, 0);
   
   // Set the background color
   dbClearScreen(dbRGB(133, 194, 122));
   
   // Paste the image, black is transparent
   dbPasteImage(circleImageId, 320/2, 320/4, 1);
   
   do {
      dbSync();
   }
   while (waitWindowEvent(1) != WM_CLOSE);
   
   dbCloseScreen();
   
   return 0;
}

Example with sprites:

#include <puregdk/core/puregdk.h>
#include <puregdk/initPureGDK.h>
#include <puregdk/simpleWindow.h>

#include <windows.h>

using namespace std;

int __stdcall WinMain(HINSTANCE, HINSTANCE, LPSTR, int) {
   int screenWidth = 640;
   int screenHeight = 480;
   
   if (!initPureGDK("gdkengine.dll"))
      return 1;
   
   HWND hWnd = openWindow(0, 0, screenWidth, screenHeight,
      "PureGDK - Game Developer's Toolkit",  WS_OVERLAPPED | WS_CLIPSIBLINGS |
      WS_CAPTION | WS_SYSMENU | WS_CLIPCHILDREN, true);
   
   dbOpenScreen(hWnd, 0, 0, screenWidth, screenHeight);
   
   ShowWindow(hWnd, SW_SHOW);
   
   dbAutoCamOff();
   
   // Must be called before image is loaded
   dbSetImageChromaKey(255, 0, 255);
   
   // Get circle
   dbInk(dbRGB(255, 0, 255), 0);
   dbBox(0, 0, 320, 320);
   dbInk(dbRGB(0, 0, 0), 0);
   dbCircle(320/2, 320/2, 150);
   int circleImageId = dbGetImage(0, 0, 320, 320, 0);
   
   // Set background color
   dbInk(dbRGB(133,194,122),0);
   dbBox(0, 0, screenWidth, screenHeight);
   int imageBackdropId = dbGetImage(0, 0, screenWidth, screenHeight);
   dbTextureBackdrop(imageBackdropId);
   
   int surface = dbCreateObjectPlane(2, 2, 0);
   
   dbPositionCamera(0, 0, 2);
   dbPointCamera(0, 0, 0);
   
   dbTextureObject(surface, circleImageId);
   dbSetObjectTransparency(surface, kGDK_DrawFirstWithAlpha);
   
   do {
      dbSync();
   }
   while (waitWindowEvent(1) != WM_CLOSE);
   
   dbCloseScreen();
   
   return 0;
}

+ Code Snippet

#include <puregdk/core/puregdk.h>
#include <puregdk/initPureGDK.h>
#include <puregdk/simpleWindow.h>

#include <windows.h>

using namespace std;

int __stdcall WinMain(HINSTANCE, HINSTANCE, LPSTR, int) {
   int screenWidth = 640;
   int screenHeight = 480;
   
   if (!initPureGDK("gdkengine.dll"))
      return 1;
   
   HWND hWnd = openWindow(0, 0, screenWidth, screenHeight,
      "PureGDK - Game Developer's Toolkit",  WS_OVERLAPPED | WS_CLIPSIBLINGS |
      WS_CAPTION | WS_SYSMENU | WS_CLIPCHILDREN, true);
   
   dbOpenScreen(hWnd, 0, 0, screenWidth, screenHeight);
   
   ShowWindow(hWnd, SW_SHOW);
   
   dbAutoCamOff();
   
   // Must be called before image is loaded
   dbSetImageChromaKey(255, 0, 255);
   
   // Get circle
   dbInk(dbRGB(255, 0, 255), 0);
   dbBox(0, 0, 320, 320);
   dbInk(dbRGB(0, 0, 0), 0);
   dbCircle(320/2, 320/2, 150);
   int circleImageId = dbGetImage(0, 0, 320, 320, 0);
   
   // Set background color
   dbInk(dbRGB(133,194,122),0);
   dbBox(0, 0, screenWidth, screenHeight);
   int imageBackdropId = dbGetImage(0, 0, screenWidth, screenHeight);
   dbTextureBackdrop(imageBackdropId);
   
   int surface = dbCreateObjectPlane(2, 2, 0);
   
   dbPositionCamera(0, 0, 2);
   dbPointCamera(0, 0, 0);
   
   dbTextureObject(surface, circleImageId);
   dbSetObjectTransparency(surface, kGDK_DrawFirstWithAlpha);
   
   do {
      dbSync();
   }
   while (waitWindowEvent(1) != WM_CLOSE);
   
   dbCloseScreen();
   
   return 0;
}

Example with 3d:

#include <puregdk/core/puregdk.h>
#include <puregdk/initPureGDK.h>
#include <puregdk/simpleWindow.h>

#include <windows.h>

using namespace std;

int __stdcall WinMain(HINSTANCE, HINSTANCE, LPSTR, int) {
   int screenWidth = 640;
   int screenHeight = 480;
   
   if (!initPureGDK("gdkengine.dll"))
      return 1;
   
   HWND hWnd = openWindow(0, 0, screenWidth, screenHeight,
      "PureGDK - Game Developer's Toolkit",  WS_OVERLAPPED | WS_CLIPSIBLINGS |
      WS_CAPTION | WS_SYSMENU | WS_CLIPCHILDREN, true);
   
   dbOpenScreen(hWnd, 0, 0, screenWidth, screenHeight);
   
   ShowWindow(hWnd, SW_SHOW);
   
   dbAutoCamOff();
   
   // Must be called before image is loaded
   dbSetImageChromaKey(255, 0, 255);
   
   // Get circle
   dbInk(dbRGB(255, 0, 255), 0);
   dbBox(0, 0, 320, 320);
   dbInk(dbRGB(0, 0, 0), 0);
   dbCircle(320/2, 320/2, 150);
   int circleImageId = dbGetImage(0, 0, 320, 320, 0);
   
   // Set background color
   dbInk(dbRGB(133,194,122),0);
   dbBox(0, 0, screenWidth, screenHeight);
   int imageBackdropId = dbGetImage(0, 0, screenWidth, screenHeight);
   dbTextureBackdrop(imageBackdropId);
   
   int surface = dbCreateObjectPlane(2, 2, 0);
   
   dbPositionCamera(0, 0, 2);
   dbPointCamera(0, 0, 0);
   
   dbTextureObject(surface, circleImageId);
   dbSetObjectTransparency(surface, kGDK_DrawFirstWithAlpha);
   
   do {
      dbSync();
   }
   while (waitWindowEvent(1) != WM_CLOSE);
   
   dbCloseScreen();
   
   return 0;
}

+ Code Snippet

#include <puregdk/core/puregdk.h>
#include <puregdk/initPureGDK.h>
#include <puregdk/simpleWindow.h>

#include <windows.h>

using namespace std;

int __stdcall WinMain(HINSTANCE, HINSTANCE, LPSTR, int) {
   int screenWidth = 640;
   int screenHeight = 480;
   
   if (!initPureGDK("gdkengine.dll"))
      return 1;
   
   HWND hWnd = openWindow(0, 0, screenWidth, screenHeight,
      "PureGDK - Game Developer's Toolkit",  WS_OVERLAPPED | WS_CLIPSIBLINGS |
      WS_CAPTION | WS_SYSMENU | WS_CLIPCHILDREN, true);
   
   dbOpenScreen(hWnd, 0, 0, screenWidth, screenHeight);
   
   ShowWindow(hWnd, SW_SHOW);
   
   dbAutoCamOff();
   
   // Must be called before image is loaded
   dbSetImageChromaKey(255, 0, 255);
   
   // Get circle
   dbInk(dbRGB(255, 0, 255), 0);
   dbBox(0, 0, 320, 320);
   dbInk(dbRGB(0, 0, 0), 0);
   dbCircle(320/2, 320/2, 150);
   int circleImageId = dbGetImage(0, 0, 320, 320, 0);
   
   // Set background color
   dbInk(dbRGB(133,194,122),0);
   dbBox(0, 0, screenWidth, screenHeight);
   int imageBackdropId = dbGetImage(0, 0, screenWidth, screenHeight);
   dbTextureBackdrop(imageBackdropId);
   
   int surface = dbCreateObjectPlane(2, 2, 0);
   
   dbPositionCamera(0, 0, 2);
   dbPointCamera(0, 0, 0);
   
   dbTextureObject(surface, circleImageId);
   dbSetObjectTransparency(surface, kGDK_DrawFirstWithAlpha);
   
   do {
      dbSync();
   }
   while (waitWindowEvent(1) != WM_CLOSE);
   
   dbCloseScreen();
   
   return 0;
}

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WLGfx

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Years of Service

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Joined: 1st Nov 2007

Location: NW United Kingdom

Posted: 11th Aug 2011 19:06

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I've used the chromakeying or colorkey. It is what I'm after but what I'm going to try and do is grab a large image (forgetting memory usage for the time being) and when it comes to pasting it to the screen, I'm going to use a clipping rectangle.

I understand that png's don't actually need the setimagecolorkey or chromakey to be set before using. That all depends on whether an image of a spiders web saves smaller as a png or a jpg file.

I've always been one for optimising code for speed and with these new (well, been around for years) processors, trying to write C code for being cache friendly is difficult. So I'm always trying not to go the long way round for doing things.

Thanks Mistrel...

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Dark GDK / Create an image or bitmap with a different depth?