Index Of Dhoom 3

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Kayleigh Telega

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Aug 3, 2024, 4:48:01 PM8/3/24

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At startup, the application's environment is initialized and NSRunLoop calls applicationDidFinishLaunching. This is where you get to run something, for 5 seconds, after what the function is interrupted. During this time period, you can register your code to receive notification of touch screen events via function pointers.

In order to refresh the screen on a regular interval, we need to create new events via an NSTimer object that will be binded to NSRunLoop. NSTimer defines marks in time, NSRunLoop will check "regularly" if a mark had been passed and will call your function pointer. Most developer setup NSTimer to call a custom method: hostFrame at a "wished" frequency of 30 Hz.

There is plenty of problem with such a design:

Because a NSRunLoop object can be busy, refreshing accuracy is only 100ms :( !
"Marks" are set in advance, this means that if the hostGameFrame method overRun the NSTimer marks, next trigger won't be as soon as possible but on the next scheduled mark ( See "Timer Sources" in Apple's documentation on NSRunLoop).

Quote:You can configure timers to generate events only once or repeatedly. A repeating timer reschedulesitself automatically based on the scheduled firing time, not the actual firing time. For example,if a timer is scheduled to fire at a particular time and every 5 seconds after that, the scheduledfiring time will always fall on the original 5 second time intervals, even if the actual firingtime gets delayed.

If this happen the CPU ends up being idle until the next NSTimer time mark is reached but more important: A frame is skipped.

Even one single frame taking too long to process can have disastrous impact on the framerate:

Critical sections of the code (mainly user inputs) are protected via an Unix mutex. The rendering loop run as fast as it can but is starved via a semaphore on sem_wait. iPhoneAsyncTic increase the counter sem_post.

This design actually share a lot of similarities with the technique called "Triple buffering" which goal is to totally decouple the GPU from the display's refresh rate. Here the goal is to decouple the CPU from the NSTimer ticks:

Shorten the runtime of the mainThread to never miss an NSTimer mark.
The CPU is never idle, the high priority mainThread will interrupt the GameThread from time to time but that's it.

Note: The rendering context is grabed by the Game Thread at startup [EAGLContext setCurrentContext:context] without usage of a EAGLSharegroup, effectively sharing the context accross two threads: It's a bad thing but it seems to be working fine anyway.

I was surprised not to find any usage of CADisplayLink, an object allowing to link a method call with a screen refresh that showed HUGE performance (at least according to my experimentations. But it is available on 3.0 firmware only so this design will allow more people to play the game, which makes a lot of sense commercially speaking.

Early attempts to port Doom to OpenGL built new WAD (Doom archive format). They exploited the WAD format capability to store pretty much anything (the original Doom WAD contained graphics, sounds, map, via different lumps types.) to create a new type of entry and store the 3D data organized as triangles. This is not the approach in Doom on iPhone, the world is "unified" in 3D primitives at the beginning of each level.

Once the world is 3D consistent, each frame is rendered via an hybrid CPU/GPU process:

Generate and upload OpenGL's GL_PROJECTION and GL_MODELVIEW matrices.
Perform extra view transformation and read back GL_MODELVIEW matrix from the GPU so pre-calculations can be performed.
Use the BSP to walk the world near to far. Nothing is rendered at this point, only visibility edicts are generated and stored in gld_drawinfo.
- For each wall, use the matrix that was read back to precalulate the X screen space coordinate where OpenGL will render the wall and maintain an occlusion array occlusion[MAX_SCREENWIDTH+2], nothing is rendered at this point.
- If a subSector is visible, mark its parent sector as "to be rendered"
- If a sector contains a thing, generate an impostor to render it.
For the three groups of items, perform a quicksort based on the textureId.
Render all walls, sectors and things. One batch per texture.
Switch OpenGL to 2D and perform post effect to fake palette effects if necessary and draw player sprites etc..

All of this takes place in IR_RenderPlayerView.
void IR_RenderPlayerView (player_t* player) [..]// clean occlusion arraymemset( occlusion, 0, sizeof( occlusion ) );// Reset the fake palette.gld_SetPalette(-1);// To make it easier to accurately mimic the GL model to screen transformation,// this is set up so that the projection transformation is also done in the// modelview matrix, leaving the projection matrix as an identity. This means// that things done in eye space, like lighting and fog, won't work, but// we don't need them.glMatrixMode(GL_PROJECTION);glLoadIdentity();glMatrixMode(GL_MODELVIEW);glLoadIdentity();infinitePerspective(64.0f, 320.0f/200.0f, 5.0f/100.0f);IR_RenderBSPNode( numnodes-1 );NewDrawScene(player);// Perform fake palette effectgld_EndDrawScene();
Trivia :

Palette: Because Doom classic was using a VGA indexed palette to perform some special effects, this feature had to be replicated via a post effect in gld_EndDrawScene.
Scene processing and drawing are now two distinct phases (IR_RenderBSPNode and NewDrawScene ), the way things started to be done in Quake.
Matrices are handled in an unusual fashion:
- Matrices are built, uploaded to OpenGL, manipulated via the drivers and then read back from OpenGL. The usual way is to build the final matrix and upload it.
- The perspective projection is stored in GL_MODELVIEW, leaving GL_PROJECTION has identity matrix.
The BSP structure allows to walks the world near to far. But just before drawing, triangles are sorted via quicksort on the textureID. This allows to reduce the number of texture switch and reduce the number of drawing calls (by increasing the batch size).

Next: Video illustrating the drawing order: distance is not relevant anymore, triangles are drawn in batches of same texture. this is possible because Alpha testing is activated.

Your browser does not support the video tag.

Contrary to Doom93, partly transparent walls are not drawn at the end with the "things" because of the GPU's ability to use Alpha testing and Depth testing. The same POV was used as a video in the Classic Doom article. Again the priority of texture ID over distance is obvious.

Your browser does not support the video tag.

Trivia :

Using Aplha testing on a tile-based deferred renderer (TBDR) such as the iPhones is highly inefficient because it introduces uncertainty in the GPU pipeline. But it seems it gets the job for Doom, so why not ?

Jai Dixit (Abhishek Bachchan) is newly transferred to Mumbai Police and takes over the case of various heists that have occurred in Mumbai involving a gang of motorcyclists that steal and then leave without being seen. Employing the help of a talented motorcyclist and mechanic Ali (Uday Chopra), they try to track down the group of thieves and stop them before they complete their next heist.

Ya action scenes are better than dhoom 1 and dhoom 2 but overall movie is a flop its dragging good storyline bad execution could have been better .Zindagi milegi na dobora,dil chahta hai and rang de basanti are must watch and if you like gangster movies gangs of wasseypur I and II is a must watch.

Experts state that, like all other Rajkumar Hirani films, his recent release, PK seems to be enjoying a very high repeat index. In fact, this time around it is the highest ever for any film in Hindi cinema.

The film released on December 19 not just opened to a fantastic number at the box office, but also showed phenomenal growth with each passing day. We saw the highest rate of growth in this film. The film has even broken the record and collected the highest amount in the first week (182.58 cr) of its release which only reiterates the fact that a major chunk of the audience is going to the theatres to watch the film more than once.

The purpose of this study is to determine the survival rate of dental implants placed immediately into fresh extraction sockets in the maxillary anterior region by clinically evaluating the peri-implant soft tissue health and by radiographically evaluating the bone height mesial and distal to the implants.

Patients with maxillary anterior teeth indicated for extraction were selected. Indicated teeth were extracted, sockets were prepared and implants were placed into prepared sockets. After the integration period, prostheses were cemented. Patients were reviewed at three-month intervals after prosthesis placement for a period of one year with evaluation of all clinical and radiographic parameters.

Causes for extraction of teeth were root fractures, endodontic failures, internal resorption, external resorption, teeth with open apex and over-retained deciduous teeth. The mean plaque index and gingival index showed a decrease in values during the follow-up period. All implants were immobile. Radiographic analysis using Image J software (of the peri-apical radiographs) showed significant bone remodeling around the neck of the implants. Immediate implant survival rate was 100% during one-year follow-up.

Thus, with regard to implant survival, there seems to be no reason to refrain from placement of implants into extraction sockets in the maxillary anterior region when the sites are carefully selected.