BGE: Various render improvements.

bge.logic.setRender(flag) to enable/disable render.
    The render pass is enabled by default but it can be disabled with
    bge.logic.setRender(False).
    Once disabled, the render pass is skipped and a new logic frame starts
    immediately. Note that VSync no longer limits the fps when render is off
    but the 'Use Frame Rate' option in the Render Properties still does.
    To run as many frames as possible, untick the option
    This function is useful when you don't need the default render, e.g.
    when doing offscreen render to an alternate device than the monitor.
    Note that without VSync, you must limit the frame rate by other means.

fbo = bge.render.offScreenCreate(width,height,[,samples=0][,target=bge.render.RAS_OFS_RENDER_BUFFER])
    Use this method to create an offscreen buffer of given size, with given MSAA
    samples and targetting either a render buffer (bge.render.RAS_OFS_RENDER_BUFFER)
    or a texture (bge.render.RAS_OFS_RENDER_TEXTURE). Use the former if you want to
    retrieve the frame buffer on the host and the latter if you want to pass the render
    to another context (texture are proper OGL object, render buffers aren't)
    The object created by this function can only be used as a parameter of the
    bge.texture.ImageRender() constructor to send the the render to the FBO rather
    than to the frame buffer. This is best suited when you want to create a render
    of specific size, or if you need an image with an alpha channel.

bge.texture.<imagetype>.refresh(buffer=None, format="RGBA", ts=-1.0)
    Without arg, the refresh method of the image objects is pretty much a no-op, it
    simply invalidates the image so that on next texture refresh, the image will
    be recalculated.
    It is now possible to pass an optional buffer object to transfer the image (and
    recalculate it if it was invalid) to an external object. The object must implement
    the 'buffer protocol'. The image will be transfered as "RGBA" or "BGRA" pixels
    depending on format argument (only those 2 formats are supported) and ts is an
    optional timestamp in the image depends on it (e.g. VideoFFmpeg playing a video file).
    With this function you don't need anymore to link the image object to a Texture
    object to use: the image object is self-sufficient.

bge.texture.ImageRender(scene, camera, fbo=None)
    Render to buffer is possible by passing a FBO object (see offScreenCreate).

bge.texture.ImageRender.render()
    Allows asynchronous render: call this method to render the scene but without
    extracting the pixels yet. The function returns as soon as the render commands
    have been send to the GPU. The render will proceed asynchronously in the GPU
    while the host can perform other tasks.
    To complete the render, you can either call refresh() directly of refresh the texture
    to which this object is the source. Asynchronous render is useful to achieve optimal
    performance: call render() on frame N and refresh() on frame N+1 to give as much as
    time as possible to the GPU to render the frame while the game engine can perform other tasks.

Support negative scale on camera.
    Camera scale was previously ignored in the BGE.
    It is now injected in the modelview matrix as a vertical or horizontal flip
    of the scene (respectively if scaleY<0 and scaleX<0).
    Note that the actual value of the scale is not used, only the sign.
    This allows to flip the image produced by ImageRender() without any performance
    degradation: the flip is integrated in the render itself.

Optimized image transfer from ImageRender to buffer.
    Previously, images that were transferred to the host were always going through
    buffers in VideoTexture. It is now possible to transfer ImageRender
    images to external buffer without intermediate copy (i.e. directly from OGL to buffer)
    if the attributes of the ImageRender objects are set as follow:
       flip=False, alpha=True, scale=False, depth=False, zbuff=False.
       (if you need to flip the image, use camera negative scale)

1 files changed, 61 insertions, 0 deletions

diff --git a/doc/python_api/rst/bge.render.rst b/doc/python_api/rst/bge.render.rst
index 3b565e294dd..02c3beef672 100644
--- a/doc/python_api/rst/bge.render.rst
+++ b/doc/python_api/rst/bge.render.rst
@@ -90,6 +90,48 @@ Constants
 
    Right eye being used during stereoscopic rendering.
 
+.. data:: RAS_OFS_RENDER_BUFFER
+
+   The pixel buffer for offscreen render is a RenderBuffer. Argument to :func:`offScreenCreate`
+
+.. data:: RAS_OFS_RENDER_TEXTURE
+
+   The pixel buffer for offscreen render is a Texture. Argument to :func:`offScreenCreate`
+
+
+*****
+Types
+*****
+
+.. class:: RASOffScreen
+
+   An off-screen render buffer object. 
+
+   Use :func:`offScreenCreate` to create it.
+   Currently it can only be used in the :class:`bge.texture.ImageRender`
+   constructor to render on a FBO rather than the default viewport.
+
+  .. attribute:: width
+
+     The width in pixel of the FBO
+
+     :type: integer
+
+  .. attribute:: height
+
+     The height in pixel of the FBO
+
+     :type: integer
+
+  .. attribute:: color
+
+     The underlying OpenGL bind code of the texture object that holds
+     the rendered image, 0 if the FBO is using RenderBuffer.
+     The choice between RenderBuffer and Texture is determined
+     by the target argument of :func:`offScreenCreate`.
+
+     :type: integer
+
 
 *********
 Functions
@@ -362,3 +404,22 @@ Functions
    Get the current vsync value
 
    :rtype: One of VSYNC_OFF, VSYNC_ON, VSYNC_ADAPTIVE
+
+.. function:: offScreenCreate(width,height[,samples=0][,target=bge.render.RAS_OFS_RENDER_BUFFER])
+
+   Create a Off-screen render buffer object.
+
+   :arg width: the width of the buffer in pixels
+   :type width: integer
+   :arg height: the height of the buffer in pixels
+   :type height: integer
+   :arg samples: the number of multisample for anti-aliasing (MSAA), 0 to disable MSAA
+   :type samples: integer
+   :arg target: the pixel storage: :data:`RAS_OFS_RENDER_BUFFER` to render on RenderBuffers (the default),
+      :data:`RAS_OFS_RENDER_TEXTURE` to render on texture. 
+      The later is interesting if you want to access the texture directly (see :attr:`RASOffScreen.color`).
+      Otherwise the default is preferable as it's more widely supported by GPUs and more efficient.
+      If the GPU does not support MSAA+Texture (e.g. Intel HD GPU), MSAA will be disabled.
+   :type target: integer
+   :rtype: :class:`RASOffScreen`
+