For Reindeer 0.1.0 (compatibility version 0.1)
Copyright © 2008, 2009, 2010 Patrik Olsson
Table of Contents
List of Tables
List of Examples
Table of Contents
Reindeer is a C library for the rendering of virtual scenes, mainly in three dimensions. The library dynamically loads backend modules to do the rendering.
Any number of rendering contexts can live at the same time. Contexts are tied to a backend and backends are automatically loaded and unloaded on demand. Resources are defined globally and can be used by any number of contexts at the same time, even in different backends.
The main goal is to make it easier for developers to write applications that have many rendering contexts with shared resources and automatic state management. Another advantage is that the user can choose in which way a scene should be rendered without recompiling the application. For example, a scene could be rendered with a rasterizer like OpenGL at one point, and with a raytracer at another. Reindeer can also be used to get portable graphics output. Reindeer is not a scene-graph library or a game engine, but it can be used to implement them.
It's still up to the application to create and manage the native contexts that the Reindeer backends can work on. For example, an application would still need to use GLX or equivalent to be able to use the OpenGL backend. The Reindeer project also provides a package called GTK-Reindeer that makes this easier for developers of GTK+ applications.
Assuming you have not already found a copy of Reindeer, you can find one at the download site of the project at GNU Savannah. Here you can also find the latest version.
There might also be built packages you can get from the software repository of your operating system distribution. If you just want to get Reindeer to use programs that need the Reindeer library it's usually here you get it from.
It is also possible to obtain the very latest development versions of Reindeer from the source code repository at http://git.savannah.gnu.org/cgit/reindeer.git/.
Example 2.1. A simple Reindeer application
#include <ren/ren.h>
...
static void configure (RenReindeer *r);
static void draw (RenReindeer *r);
int main (int argc, char **argv)
{
ren_library_init ();
/* Set up native OpenGL context. */
...
/* Set up Reindeer context. */
RenBackend *backend = ren_backend_lookup ("opengl");
RenReindeer *r = ren_reindeer_new (backend);
for (;;)
{
Event *event = ...;
switch (event->code)
{
case ...CONFIGURE:
configure (r, ((ConfigureEvent*) event)->rect);
break;
case ...REDRAW:
draw (r);
break;
case ...QUIT;
goto EXIT;
}
}
EXIT:
/* Destroy Reindeer context. */
ren_reindeer_unref (r);
ren_backend_unuse (backend);
/* Clean up native context. */
...
/* Exit Reindeer library. */
ren_library_exit ();
}
static void configure (RenReindeer *r, ...Rect rect)
{
static ren_bool inited = FALSE;
/* Make native OpenGL context current */
...
if (inited == FALSE)
{
/* Initialize the Reindeer context. */
ren_init (r);
inited = TRUE;
}
ren_viewport (rect.x, rect.y, rect.width, rect.height);
/* Make no native OpenGL context current */
...
}
static void draw (RenReindeer *r)
{
/* Make native OpenGL context current */
...
ren_clear (r, REN_BUFFER_COLOR);
/* Make no native OpenGL context current */
...
}
This example shows how to set up a simple Reindeer application with
OpenGL. Similar code would be used for other backends as well. The
function configure is assumed to be called once
when the graphical window is put on the screen and then each time it is
modified (e.g. resized). The function draw is
assumed to be called each time the window needs to be redrawn. It will
clear the window in the default color (black).
One could add a timer that calls another function, e.g.
update, that will modify Reindeer resources (vertex
arrays, textures, colors, matrices). In this example however, no
Reindeer resource is used at all.
Some parts are left out in this example because they are different on different platforms. For example, if the program is to be run on the X Window System then X and GLX commands would be used in place of the missing code. There are libraries that will do this for you too. As far as OpenGL goes there is for example GtkGLExt for GTK+ which is however also Reindeer-unaware. For something that works with more backends there is GTK-Reindeer, and it also integrates nicely with the Reindeer library.
Reindeer is intentionally not entirely thread safe. This is because it is much more efficient if the application locks on large amount of operations rather than if Reindeer locks on individual operations.
Generally, there is no locking between modifying Reindeer resources and reading from them. Thus applications should make sure that a Reindeer resource is never modified when it may be being read at the same time. In practice the most efficient and easiest way to fulfil this requirement is to separate scene updating (modifying) from scene redrawing (reading). It's perfectly fine to read from the same resource at the same time so any number of Reindeer contexts may render at the same time. However, updating should never be done simultaneously with any rendering that could potentially use the resources being updated.
Table 2.1. Table of Reindeer types
| C Type | RenType value | Minimum bit-width | Description |
|---|---|---|---|
| ren_sint08 | REN_TYPE_SINT08 | 8 | Signed integer |
| ren_uint08 | REN_TYPE_UINT08 | 8 | Unsigned integer |
| ren_sint16 | REN_TYPE_SINT16 | 16 | Signed integer |
| ren_uint16 | REN_TYPE_UINT16 | 16 | Unsigned integer |
| ren_sint32 | REN_TYPE_UINT32 | 32 | Signed integer |
| ren_uint32 | REN_TYPE_SINT32 | 32 | Unsigned integer |
| ren_sint64 | REN_TYPE_SINT64 | 64 | Signed integer |
| ren_uint64 | REN_TYPE_UINT64 | 64 | Unsigned integer |
| ren_sfloat | REN_TYPE_SFLOAT | 32 | Single-precision floating-point number |
| ren_double | REN_TYPE_DFLOAT | 64 | Double-precision floating-point number |
| ren_bool | REN_TYPE_BOOL | 1 | Boolean. False (FALSE) is zero, true (TRUE) is non-zero. |
| ren_size | n/a | System dependent | Integer large enough to hold the numeric value of a pointer. |
Implementations are not required to correctly interpret bits outside the minimum range. Thus, if a variable has a value outside the defined ranges it will lead to undefined behavior.
Reindeer types are not necessarily identical to the corresponding standard C types. Never cast pointers of C types to pointers of Reindeer types or vice versa.
RenType is an enumerated type generally used to describe what type is being pointed at. Since the type ren_size is never used in this context, it does not have a value in RenType.
The following function returns the size of type
in bytes.
ren_size ren_type_sizeof( | RenType type); |
ren_bool ren_library_init( | RenError** error); |
Initialize the library. This must be called before any other library
function is called. If it returns FALSE, do not
continue using the library.
void ren_library_exit( | void); |
Finalize the library. No library function must be called after this point. It's not possible to initialize it again. Typically this will be called shortly before exiting the program.
RenBackend* ren_backend_lookup( | const char* name, |
RenError** error); |
Try to find a backend. If the backend is available for use it will be
returned and its use count is increased. When you don't need the backend
loaded anymore, use ren_backend_unuse. If the
backend is not available for use then NULL will be returned (with
*error set to point to a RenError with error
information).
ren_bool ren_backend_use( | RenBackend* backend, |
RenError** error); |
Increases the use count of the Reindeer backend. If the backend was
previously unloaded (use count was zero), this will also load it.
Returns TRUE if successful, and
FALSE if not (with *error
set to point to a RenError with error information).
void ren_backend_unuse( | RenBackend* backend); |
Decreases the use count of the Reindeer backend. When its use count drops to 0, it will be unloaded automatically.
RenReindeer* ren_reindeer_new( | RenBackend* backend); |
Load a Reindeer context for a backend. Note that Reindeer contexts are not necessarily equivalent to the contexts of the target API. However, usually one wants to pair them. Backends should mention in their respective reference manuals how one is supposed to set up Reindeer contexts with it and how they work together with the native contexts of the backend.
Some Reindeer functions will take a Reindeer context. It is often the case that the backend must be in a certain state before those calls are valid. For example, OpenGL needs to have the associated OpenGL context current. These functions will be marked with "virtual" in their descriptions.
RenReindeer* ren_reindeer_ref( | RenReindeer* r); |
Increases the reference count of the Reindeer context and then returns it.
void ren_reindeer_unref( | RenReindeer* r); |
Decreases the reference count of the Reindeer context. When its reference count drops to 0, it will be destroyed automatically.
RenBackend* ren_reindeer_backend( | RenReindeer* r); |
Get the backend a Reindeer context uses.
virtual ren_bool ren_init( | RenReindeer* r); |
Virtual function to initialize a Reindeer context. This must be called before any other virtual Reindeer context function.
Table of Contents
The following storage types wrap around data. When documentation mention taking the value of these types it means the actual data is read and used, rather than keeping the reference to the data for later use. Since the data may be copied by the backends it is necessary to signal changes in the underlying data so that the backends can update their copies.
RenColorFormat
REN_COLOR_FORMAT_RGBREN_COLOR_FORMAT_RGBAREN_COLOR_FORMAT_DEPTHRepresents a color format, with components in a specific order. "R" means red, "G" means green, "B" means blue and "A" means alpha.
RenColor* ren_color_new( | RenColorFormat format, |
RenType type); |
Define a new color. Color data will be internally allocated, in the
format specified by format and
type. Any value for format
is valid. Valid values for type are unsigned
integers up to 32 bit and floating point types.
RenColor* ren_color_ref( | RenColor* color); |
Increases the reference count of the Color instance and then returns it.
void ren_color_unref( | RenColor* color); |
Decreases the reference count of the Color instance. When its reference count drops to 0, it will be destroyed automatically.
void* ren_color_begin_edit( | RenColor* color); |
Get the internal data of the color with the intention of modifying it. This function may lock while some other thread is already using the data.
void ren_color_end_edit( | RenColor* color); |
Mark an end of modifying the internal data. The pointer received with
ren_color_begin_edit must not be used anymore.
ren_size ren_color_format_sizeof( | RenColorFormat format, |
RenType type); |
Returns in bytes the size of the color format used together with
type. A Color instance created with this format
will have internal data (as returned with
ren_color_begin_edit) of this size. The valid
values for format and type
are the same as in ren_color_new.
Data blocks represents a large block of data. Some resources use a data block as a source of data. The same data block may be used together with many resources.
RenDataBlock* ren_data_block_new( | ren_size size, |
RenUsage usage); |
Define a new data block. The data will be internally allocated, with the
size as specified. The parameter usage specifies
how often the data block is intended to be used and modified, which may
allow the implementation to be more efficient.
RenUsage
REN_USAGE_DONT_CARELet backend choose a generally good solution. Not recommended.
REN_USAGE_IMMUTABLEData cannot be changed and thus never is changed.
REN_USAGE_STATICData is modified very seldom or never, and used many times.
REN_USAGE_DYNAMICData is modified often, but also used many times between modifications.
REN_USAGE_STREAMData is modified almost as often as it is used.
RenDataBlock* ren_data_block_ref( | RenDataBlock* data_block); |
Increases the reference count of the DataBlock instance and then returns it.
void ren_data_block_unref( | RenDataBlock* data_block); |
Decreases the reference count of the DataBlock instance. When its reference count drops to 0, it will be destroyed automatically.
void* ren_data_block_begin_edit( | RenDataBlock* data_block); |
Get the internal data of the data block with the intention of modifying it. This function may lock while some other thread is already using the data.
void ren_data_block_end_edit( | RenDataBlock* data_block); |
Mark an end of modifying the internal data. The pointer received with
ren_data block_begin_edit must not be used anymore.
void ren_data_block_changed( | RenDataBlock* data_block, |
| ren_size from, | |
ren_size count); |
Notify that a part of the data has been changed. This is done between
ren_data_block_begin_edit and
ren_data_block_end_edit. The parameter
count may be 0 to denote everything to the end.
Matrices are mainly used in Reindeer to do linear transformations as described in Chapter 5, Transformation.
RenMatrix* ren_matrix_new( | ren_size width, |
| ren_size height, | |
| RenType type, | |
ren_bool transposed); |
Define a new matrix. Matrix data will be internally allocated, with matrix width, height and element type as specified.
Matrix data is expected to be stored in column-major order. If your
program uses row-major order matrices, you should set
transposed to TRUE,
otherwise set it to FALSE.
RenMatrix* ren_matrix_ref( | RenMatrix* matrix); |
Increases the reference count of the Matrix instance and then returns it.
void ren_matrix_unref( | RenMatrix* matrix); |
Decreases the reference count of the Matrix instance. When its reference count drops to 0, it will be destroyed automatically.
void* ren_matrix_begin_edit( | RenMatrix* matrix); |
Get the internal data of the matrix with the intention of modifying it. This function may lock while some other thread is already using the data.
void ren_matrix_end_edit( | RenMatrix* matrix); |
Mark an end of modifying the internal data. The pointer received with
ren_matrix_begin_edit must not be used anymore.
Vectors are mainly used in Reindeer to describe a list of numbers. They may be used to describe individual positions or directions, but more generally they may represent anything that can be described with a list of numbers. They are never used for large arrays of positions or directions, because then a RenVectorArray is used. Also, they are never used to represent colors because then RenColor is preferred.
RenVector* ren_vector_new( | ren_size length, |
RenType type); |
Define a new vector. Vector data will be internally allocated, with vector length and element type as specified.
RenVector* ren_vector_ref( | RenVector* vector); |
Increases the reference count of the Vector instance and then returns it.
void ren_vector_unref( | RenVector* vector); |
Decreases the reference count of the Vector instance. When its reference count drops to 0, it will be destroyed automatically.
void* ren_vector_begin_edit( | RenVector* vector); |
Get the internal data of the vector with the intention of modifying it. This function may lock while some other thread is already using the data.
void ren_vector_end_edit( | RenVector* vector); |
Mark an end of modifying the internal data. The pointer received with
ren_vector_begin_edit must not be used anymore.
RenBuffer
REN_BUFFER_COLORREN_BUFFER_DEPTHA bit field type. Represents a set of buffers.
void ren_clear_color( | RenReindeer* r, |
RenColor* color); |
Set color to use when clearing color buffer from the value of
color.
void ren_clear_depth( | RenReindeer* r, |
ren_dfloat depth); |
Set depth value to use when clearing depth buffer.
void ren_clear( | RenReindeer* r, |
RenBuffer buffers); |
Clear the specified buffers with the values specified with the
functions ren_clear_color and
ren_clear_depth.
void ren_viewport( | RenReindeer* r, |
| ren_uint32 x, | |
| ren_uint32 y, | |
| ren_uint32 width, | |
ren_uint32 height); |
Scale rendering to a subset of the buffer.
The transformation system in Reindeer is similar to the one used in OpenGL. There is one mode for each thing that can be transformed. The possible modes are model-view and projection. Each mode has an associated current matrix, and a stack of previous matrices saved for later use. The current matrix is the one used in transformation calculations.
The current model-view matrix is used to transform vertex positions and
normals. The projection matrix is used together with the viewport
coordinates (specified with ren_viewport) to
transform 3D coordinates to window coordinates.
RenTransformMode
REN_TRANSFORM_MODE_MODELVIEWREN_TRANSFORM_MODE_PROJECTIONRepresents a transform mode.
void ren_transform_mode( | RenReindeer r, |
RenTransformMode mode); |
Set the current transform mode to mode. This
makes the following functions manipulate the current matrix and matrix
stack associated with this mode.
void ren_transform_push( | RenReindeer* r); |
Push the current matrix to the matrix stack. The current matrix is not affected.
void ren_transform_pop( | RenReindeer* r); |
Pop the matrix stack and sets the current matrix to the retrieved matrix.
void ren_transform_set( | RenReindeer r, |
RenMatrix* matrix); |
Set the current matrix to the value of matrix.
void ren_transform_mul( | RenReindeer* r, |
RenMatrix* matrix); |
Multiply the current matrix with the value of
matrix and set the current matrix to the result.
void ren_transform_identity( | RenReindeer* r); |
Set the current matrix to be the identity matrix.
Table of Contents
Table of Contents
Version 1.3, 3 November 2008
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To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:
Copyright © YEAR YOUR NAME Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.
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If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.
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