Expresso

MPO2Stereo

The following is the code I got from Andres Hernandez [cybereality] for separating a .mpo file into 2 relative .jpeg files (left and right). The key point is to find the second jpeg's header "FFD8FFE1" and this is my first time to touch jpeg's header format. Kinda interesting.

According to Andres's idea, we all hope everyone could keep sharing any informative stuff to help others' work or research. And eventually, we could benefit from others' great achievement :)

Cool, no problem man. It would be cool if you could upload the mac version on that same MTBS thread so it can help others. MTBS can host files, there is a small "browse for file" button under the post box, then click "add file", so it is very easy to include files in a thread. I am sure there are other mac users that would appreciate it.

// MPO2Stereo:
// Converts Fujifilm MPO format 3D
// images into JPEG stereo pairs
//
// code by: 
// Andres Hernandez [cybereality]

#include <iostream>
#include <fstream>

using namespace std;

int fileSize;
char * stereoData;
char * rightData;

int main( int argc, char* argv[] ){
	// title
	printf("\n*********** MPO2Stereo [cybereality] ***********\n");
	printf("------------------------------------------------\n");

	// print usage if no arguments
	if(argc == 1){
		printf("Converts MPO files to JPEG stereo pairs.\n");
		printf("Usage: MPO2Stereo.exe File_1.MPO [.. File_N.MPO]\n");
	}
	// loop through each argument
	for( int i = 1; i < argc; i++ ){
		// get the file name
		char fileName[255];
		char fullName[255];
		// locate end of path, which is the last slash in the string
		char *ptr = strrchr(argv[i],'/');
		// make sure its a directory
		if(ptr != NULL){
			// copy remainder of string
			strcpy(fileName,ptr+1);
			// remember full name
			strcpy(fullName, fileName);
			// check if its an MPO file
			char *MPO = strstr(fileName, ".MPO");
			char *mpo = strstr(fileName, ".mpo");
			// strip file extension
			ptr = strchr(fileName,'.');
			// if the extension exists, truncate it
			if(ptr != 0) *ptr = 0;
			// make sure its an MPO file
			if(MPO == NULL && mpo == NULL){
				printf("Cannot Process: \"%s\". Not An MPO File.\n", fullName);
				// go to next file if any
				continue;
			} else {
				// print file name
				printf("Processing MPO File: \"%s\"...\n", fullName);
			}
		} else {
			// malformed directory
			printf("Invalid Directory For File: %s\n", argv[i]);
			printf("Must Include Full Directory Path To MPO File.\n");
			// skip
			continue;
		}

		// load up the MPO file
		ifstream mpoFile (argv[i], ios::in|ios::binary|ios::ate);
		// make sure we can open file
		if (mpoFile.is_open()) {
			// read the image data into a buffer
			fileSize = (int)mpoFile.tellg();
			stereoData = new char [fileSize];
			mpoFile.seekg (0, ios::beg);
			mpoFile.read (stereoData, fileSize);
			mpoFile.close();

			// start of the next image
			char startOfImage [8]= { 'F', 'F', 'D', '8', 'F', 'F', 'E', '1' };
			int imageBreak;

			// find the break point between the image pairs
			for(int i=0; i < fileSize; i+=4){
				// get block into a c string
				char block[255];
				// extract the characters
				sprintf(block, "%.2X%.2X%.2X%.2X", 
				(unsigned int)(unsigned char)stereoData[i], 
				(unsigned int)(unsigned char)stereoData[i+1], 
				(unsigned int)(unsigned char)stereoData[i+2], 
				(unsigned int)(unsigned char)stereoData[i+3]);
				// check for start of image
				if(strncmp(block, startOfImage, 8) == 0){
					// remember where the image starts
					imageBreak = i;
					cout << imageBreak << endl;
				}
			}

			// write left image to new file
			char leftName[255];
			sprintf(leftName, "%s_L.JPG", fileName);
			ofstream leftFile;
			leftFile.open (leftName, ios::out | ios::binary);
			if (leftFile.is_open()) {
				leftFile.write (stereoData, imageBreak);
				leftFile.close();
				printf("Created JPEG File: \"%s\".\n", leftName);
			} else {
				printf("Unable To Create JPEG File: \"%s\".\n", leftName);
			}
			// write right image to new file
			char rightName[255];
			sprintf(rightName, "%s_R.JPG", fileName);
			ofstream rightFile;
			rightFile.open (rightName, ios::out | ios::binary);
			if (rightFile.is_open()) {
				rightFile.write (stereoData + imageBreak, fileSize-imageBreak);
				rightFile.close();
				printf("Created JPEG File: \"%s\".\n", rightName);
			} else {
				printf("Unable To Create JPEG File: \"%s\".\n", rightName);
			}
			// delete resources
			delete[] stereoData;
		} else {
			printf("Unable To Open MPO File.\n");
		}
	}
	// all done
	printf("------------------------------------------------\n");

	// return
	return 0;
}

How to make Maya output all messages into console/terminal?

Recently, Timothy and I were talking about some interesting about message in Maya.

For daily tasks in Digimax, Timothy has to handle a mass of Maya scene files in batch way such that he can make it on schedule. But there are so many tasks and Maya scene files! He has spent some time preparing several scripts (Mel or Python, but most of them are Python) for that task. It seems work well but sometimes, he needs to get output messages from Maya for debugging and other scripts. For example, one Python script when invoked inside Maya would output a list of filtered and managed nodes in one Maya scene and after that, we can apply some other programs/scripts on nodes by this message.

Question is:

How could we redirect all Maya messages into console or terminal while Maya is invoked in GUI mode?

My first reaction was "What a weird and kinda stupid question?" 'cause it seems to be non sense to have a GUI mode Maya redirect its message to console. Because you have already opened a Maya GUI, all you have to do can be done within that GUI though. But it turns to to make sense when you are going to make use of scripts to automatically handle lots of Maya scenes (ex, 100 animation shots, each has more than one Maya scene files!). If this was the case, why did we need the GUI? How about invoking Maya as standalone mode and in that way, we all output messages were naturally redirected to console!

"Some scripts/nodes need GUI's redrawing to make it re-calculate values, such that we need Maya in GUI mode.", replied by Timothy. Well, IMHO, there should be some way to do that Dependency node's evaluation in standalone mode but we didn't know that yet. Actually, there is a likely hot topic "forcing a custom node's attribute to compute every dep graph update" in Python Inside Maya group but let's just skip it and figure out some hacking way to redirect all messages to console/terminal.

Problem Definition:

• Maya is invoked from a terminal/console as a GUI mode. All Maya messages have to be correctly redirected to the console.
• There are 3 types of messages: 1) msgs by Maya itself, 2) msgs from Mel's print and 3) msgs from Python's print.

Solution:

• We can make use of sys.__stdout__, the default standard output (terminal) to redirect Python's print.
• For Mel's print and Maya's command messages, we need to use CommandMessage.CommandOutputCallback in Maya API. Just register a CommandOutput callback and everytime there is a message, this callback would be invoked.

pymel 讓 optionVar 用起來看起來，更像 dictionary

Maya 裏頭有個非常 high level 的 mel function: optionVar，有別於其它的 functions 的簡單與立即反應，它的目的在提供一個跟 Maya session 的設定檔的存取。換個說法，你可以在一次執行 Maya 的時候，存一個自訂的變數 IamSoHandsome，然後在下一次執行時取出來用。所以你可以把它想成是 Windows 上頭的 registry、Unix-like 下的 .ooxx 個人設定檔、或是會永續存在下去的 environment variables。

optionVar 另一個優秀的地方在於，它允許你隨時更改存下來的變數的 data type。所以你可以今天把 IamSoHandsome 宣告成一個只有 0 與 1 的 boolean，然後明天改成 "yes" 與 "no" 的 string，只要直接指定給它一個新的 data type 就做到了。如下：

optionVar -iv "IamSoHandsome" 1;
...
...
optionVar -sv "IamSoHandsome" "yes";
...
...

optionVar -sv:

creates a new variable named using the first string with value given by the second string. If a variable already exists with this name, it is overridden in favour of the new value (even if the type is different).

pymel 更酷了，它讓整個 optionVar 變成了一個 dictionary-like global object（singleton class），所以你可以非常迅速地做到如下幾件事：

print optionVar["RecentFilesList"]

myVar = optionVar.get("IamSoHandsome", 1) # default to 1 if it is not in optionVar

optionVar["IamSoHandsome"] = 1
optionVar["IamSoHandsome"] = "yes"
optionVar["IamSoHandsome"] = [1, 2, 3, 4] # quickly change its value and data type without any hesitate
optionVar["IamSoHandsome"] = optionVar["IamSoHandsome"][1:] # [1,2,3,4] => [2,3,4]

我愈來愈愛用 optionVar 來提供更好的 maya GUI scripts 了 :)

Delete unknown nodes in Maya

Sometimes you need to delete unknown nodes in a Maya scene. You can do it in the following python snippet.

from pymel import *
def deleteUnknownNodes():
    # 2 things to take care of:
    #   1) you can't delete nodes from references.
    #   2) "delete" will delete all children nodes (hierarchy) in default.
    unknown = ls(type="unknown")
    unknown = filter(lambda node: not node.isReferenced(), unknown)
    for node in unknown:
        if not objExists(node):
            continue
        delete(node)

Compare it to the MEL way:

proc dgSaveDeleteUnknown()
{
    string $unknown[] = `ls -type "unknown"`;
    if( size($unknown) ) { 
        int $i; 
        for($i=0; $i<size($unknown); $i++) {
            if(!`objExists $unknown[$i]`)
                continue;
            if(!`referenceQuery -inr $unknown[$i]`)
                delete $unknown[$i];
        }
    }   
}

But why do we need to do that? I mean, why do we need to delete unknown nodes and where do those nodes come from? In theory, there should be no unknown nodes in a Maya scene file!

The answer is: Yes, you are right but if you are in an animation studio with complicated animation pipeline because animation is a vivid industry, it would happen to you!

Almost all unknown nodes come from 3rd-party Maya plugins. Let's say, your colleagues used a magical Maya plugin (ex, Realflow) such that there are some RealFlowParticlerGetMaxRange, RealflowEmitter or RealflowMesh nodes in the Maya scene. You were the downstream of this Maya scene and unfortunately, your Maya didn't know how to negotiate with those nodes (ex, you didn't have the Realflow plugin or you forgot to load it), those nodes became unknown to Maya. You could delete those nodes if they were not contributing anything to your workflow. (Ex, you are in lighting department and the rendering of fluid simulation is not your business.)