Reply To: Texture from NSBitmapImageRep to SyphonServer?

[dirrrk]

Cool!
Thanks for the link to that project. That’s very useful!! This is almost exactly the same I need to do.

However, I’m still struggling with getting this to work outside of Quartz Composer. When I look at the code of the CoGe WebKit plugin, I think the core of the code is in - (BOOL) execute:(id<QCPlugInContext>)context atTime:(NSTimeInterval)time withArguments:(NSDictionary*)arguments. This is also where the conversion from NSBitmapImageRep (webBitmap) to GLuint texture (webTexture1) is happening. From line 846 in CoGeWebKitPlugIn.m (in svn r15):

//NSLog(@"rendering...");

In the plugin a Quartz Composer outputImage is created from the texture:

#if __BIG_ENDIAN__
#define CogePrivatePlugInPixelFormat QCPlugInPixelFormatARGB8
#else
#define CogePrivatePlugInPixelFormat QCPlugInPixelFormatBGRA8
#endif

	self.outputImage =  [context outputImageProviderFromTextureWithPixelFormat:CogePrivatePlugInPixelFormat
					pixelsWide:width
					pixelsHigh:height
					name:webTexture1
					flipped:YES
					releaseCallback:_TextureReleaseCallback
					releaseContext:NULL
					colorSpace:CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB)
					shouldColorMatch:YES];

However, if I replace the Quartz Composer specific snippet above with the Syphon Server publishing stuff:

CGLLockContext(syServer.context);
[syServer publishFrameTexture:webTexture1
				textureTarget:GL_TEXTURE_RECTANGLE_EXT
				  imageRegion:NSMakeRect(0, 0, [self.webBitmap pixelsWide], [self.webBitmap pixelsHigh])
			textureDimensions:[self.webBitmap size]
					  flipped:YES];
CGLUnlockContext(syServer.context);

I still only get artifacts in my Syphon client. 🙁

My complete renderToSyphon method is the following now:

- (void) renderToSyphon {
	//NSLog(@"rendering...");
	CGLLockContext(syServer.context);

	glPushAttrib(GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT | GL_VIEWPORT);

	// create our texture
	glEnable(GL_TEXTURE_RECTANGLE_EXT);
	glGenTextures(1, &webTexture1);
	glBindTexture(GL_TEXTURE_RECTANGLE_EXT, webTexture1);

	if (self.webBitmap != NULL) {
		@synchronized(self.webBitmap) {

			glPixelStorei(GL_UNPACK_ROW_LENGTH, [self.webBitmap bytesPerRow] / [self.webBitmap samplesPerPixel]);
			glPixelStorei (GL_UNPACK_ALIGNMENT, 1); 

			glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
			glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
			glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_S, GL_CLAMP);
			glTexParameteri(GL_TEXTURE_RECTANGLE_EXT, GL_TEXTURE_WRAP_T, GL_CLAMP);

			glTexImage2D(GL_TEXTURE_RECTANGLE_EXT, 0,
				[self.webBitmap samplesPerPixel] == 4 ? GL_RGBA8 : GL_RGB8,
				[self.webBitmap pixelsWide],
				[self.webBitmap pixelsHigh],
				0,
				[self.webBitmap samplesPerPixel] == 4 ? GL_RGBA : GL_RGB,
				GL_UNSIGNED_BYTE, [self.webBitmap bitmapData]);

		}
	}
	glFlushRenderAPPLE();

	[syServer publishFrameTexture:webTexture1
					textureTarget:GL_TEXTURE_RECTANGLE_EXT
					  imageRegion:NSMakeRect(0, 0, [self.webBitmap pixelsWide], [self.webBitmap pixelsHigh])
				textureDimensions:[self.webBitmap size]
						  flipped:YES];

	glBindTexture(GL_TEXTURE_RECTANGLE_EXT, 0);
	glPopAttrib();

	CGLUnlockContext(syServer.context);
}

Could I be creating the wrong type of context for the Syphon Server? How would you create an safe offscreen context?

Or is there some really simple rendering to texture example which I can try to put in between my

CGLLockContext(syServer.context);

and

[syServer publishFrameTexture:someTexture
				textureTarget:GL_TEXTURE_RECTANGLE_EXT
				  imageRegion:NSMakeRect(0, 0, w, h)
			textureDimensions:NSMakeSize(w, h)
					  flipped:NO];
CGLUnlockContext(syServer.context);

to see if I got the other parts of my application in order, how I create the SyphonServer and the context?

… or more in general: how does one debug an OpenGL project, when the output is just artifacts from the graphics card?

(again, please forgive my opengl inexperience and ignorance)
Thanks,

Dirk