Copyright	(c) 2015 Brian W Bush
License	MIT
Maintainer	Brian W Bush <consult@brianwbush.info>
Stability	Stable
Portability	Portable
Safe Haskell	None
Language	Haskell2010

Graphics.Rendering.DLP

Contents

DLP State and Encoding
Active Frame(s)

Description

Functions for using DLP stereo with 3-D Ready Sync projectors and OpenGL. This uses the specification <http://lists.gnu.org/archive/html/bino-list/2013-03/pdfz6rW7jUrgI.pdf> and is based on the implementation for the stereo movie viewer Bino <http://git.savannah.gnu.org/cgit/bino.git/tree/src/video_output.cpp?id=bino-1.6.1#n1389>. In particular, note that this technique does not require a graphics card that supports GL_STEREO.

Below is a skeletal example illustrating the use of frame-sequential DLP. See Graphics.Rendering.DLP.Callbacks for a simpler example that uses callbacks.

main :: IO ()
main = do
  _ <- getArgsAndInitialize
  initialDisplayMode $= [WithDepthBuffer, DoubleBuffered]
  _ <- createWindow "DLP Stereo OpenGL Example"
  depthFunc $= Just Less 
  dlp <- initDlp FrameSequential                                         -- Initialize the DLP state.
  displayCallback $= display dlp                                         -- The display callback needs the DLP state.
  idleCallback $= Just (postRedisplay Nothing)                           -- The idle callback must force redisplay for frame-sequential encoding.
  mainLoop

display :: IORef DlpState -> DisplayCallback
display dlp = do
  clear [ColorBuffer, DepthBuffer]
  isLeftEye <- showEye' LeftDlp dlp                                      -- Determine whether to draw the view for the left or right eye.
  translate $ Vector3 (if isLeftEye then -0.05 else 0.05 :: GLfloat) 0 0 -- Shift the view slightly, depending on for which eye to draw.
  renderPrimitive . . .                                                  -- All of the rendering actions go here.
  drawDlp dlp                                                            -- Draw the colored DLP reference line just before swapping framebuffers.
  swapBuffers

This code has been validated with the following configuration of hardware and software:

Optoma ML550 WXGA 500 Lumen 3D Ready Portable DLP LED Projector, running 120 Hz at 1024x768 resolution
Optoma ZD302 DLP Link Active Shutter 3D Glasses
Ubuntu 15.04, 64-bit
NVIDIA Driver Version 340.93, with xorg.conf option Stereo set to 8
GHC 7.6.3
OpenGL == 2.8.0.0
GLUT == 2.4.0.0

Synopsis

DLP State and Encoding

data DlpEncoding Source

The type of DLP encoding. See the specification <http://lists.gnu.org/archive/html/bino-list/2013-03/pdfz6rW7jUrgI.pdf> for further details.

Constructors

SideBySide	Side-by-side encoding, where the left image is stored to the left of the right image in the framebuffer.
FrameSequential	Frame-sequential encoding, where left and right images alternate, each filling the whole framebuffer.
TopAndBottom	Top-and-bottom encoding, where the top image is stored above the bottom image in the framebuffer.
LeftOnly	Monoscopic with only the left eye's view.
RightOnly	Monoscopic with only the right eye's view.
QuadBuffer	Instead of DLP, use a quad buffer stereo.

Instances

Eq DlpEncoding Source
Read DlpEncoding Source
Show DlpEncoding Source

data DlpState Source

The DLP state, which tracks the sequence of frames.

initDlp :: DlpEncoding -> IO (IORef DlpState) Source

Initialize the DLP state.

drawDlp Source

Arguments

:: IORef DlpState	A reference to the current DLP state.
-> IO ()	An action to draw the DLP reference line.

Draw the DLP reference line. This action should be executed after all other drawing is complete, just before buffers are swapped.

Active Frame(s)

data DlpEye Source

Labels for the left and right eyes' views.

Constructors

LeftDlp	The left eye's view.
RightDlp	The right eye's view.

Instances

Eq DlpEye Source
Read DlpEye Source
Show DlpEye Source

showEye Source

Arguments

:: DlpEye	The eye in question.
-> DlpState	The current DLP state.
-> Bool	Whether the view of the specified eye should be shown for the current frame.

Query whether to show the view from the specified eye for the current frame. Client code should call this function to determine which views to draw into the framebuffer.

showEye' Source

Arguments

:: DlpEye	The eye in question.
-> IORef DlpState	A reference to the current DLP state.
-> IO Bool	An action for determining whether the view of the specified eye should be shown for the current frame.

Query whether to show the view from the specified eye for the current frame. Client code should call this function to determine which views to draw into the framebuffer.

whichView Source

Arguments

:: DlpEye	The eye in question.
-> DlpState	The current DLP state.
-> IO (Position, Size)	An action for computing the viewport for the eye.

Compute the viewport for the specified eye, given a DLP state.

whichView' Source

Arguments

:: DlpEye	The eye in question.
-> IORef DlpState	A reference to the current DLP state.
-> IO (Position, Size)	An actino for computing the viewport for the eye.

Compute the viewport for the specified eye, given a DLP state.