Add configuration for ARGOS_USE_DOUBLE

[allsey87]

To add a dynamics3d model to this repository, we need to correctly identify whether argos3_simulator was built with ARGOS_USE_DOUBLE set or not. Without knowing this, Bullet defaults to using 32-bit floats while the rest of the physics engine is using 64-bit floats, leading to errors such as:

malloc(): invalid size (unsorted)
Aborted (core dumped)

My approach to detecting settings is as follows:

# find the include directory
find_path (ARGOS_INCLUDE_DIR argos3/core/config.h)

if(NOT ARGOS_INCLUDE_DIR)
   message(FATAL_ERROR "Can not locate the header file: argos3/core/config.h")
endif(NOT ARGOS_INCLUDE_DIR)

# read the config.h file to get the installations configuration
file(READ ${ARGOS_INCLUDE_DIR}/argos3/core/config.h ARGOS_CONFIGURATION)

# check and set ARGOS_USE_DOUBLE
if(${ARGOS_CONFIGURATION} MATCHES "\#define ARGOS_USE_DOUBLE")
  set(ARGOS_USE_DOUBLE ON)
else(${ARGOS_CONFIGURATION} MATCHES "\#define ARGOS_USE_DOUBLE")
  set(ARGOS_USE_DOUBLE OFF)
endif(${ARGOS_CONFIGURATION} MATCHES "\#define ARGOS_USE_DOUBLE")

In my repositories, I also read a whole bunch of other settings from config.h (see ARGoSBuildOptions.cmake for details). Once this issue is fixed, I will open a PR for dynamics3d model.

[ilpincy]

A cleaner solution would be to augment the ARGoS pkgconfig file with the flags that are necessary for a correct compilation.

[allsey87]

I don't have a strong opinion here. I've never had a close look at pkg-config although at a glance it doesn't seem to do anything that we can't already do in CMake. In any case, let me know once there is a solution for defining ARGOS_USE_DOUBLE and I'll open the PR with the 3D dynamics model after that.

[ilpincy]

The issue with the purely CMake-based solution that matches config.h is that it must be copy-pasted in every sub-project. The pkg-config solution, instead, is portable and transparent: it automatically defines flags (for example -DARGOS_USE_DOUBE=ON) that are added upon detecting ARGoS. In this way, for example, we can also define compilation flags that Bullet-based plugins understand, without the need to use specialized #ifdef in the code.

[allsey87]

Fair enough, let's continue with pkg-config solution. I currently have:

prefix=/usr/local
exec_prefix=${prefix}
includedir=${prefix}/include
libdir=${exec_prefix}/lib/argos3

Name: argos3_simulator
Description: ARGoS (multi-physics multi-robot simulator)
Version: 3.0.0-beta57
Cflags: -I${includedir} -Wno-unknown-pragmas 
Libs:  -Wl,--no-as-needed -L${libdir} -largos3core_simulator

How do we go about adding variables such as ARGOS_BUILD_FOR and ARGOS_USE_DOUBLE to this file and reading them back in from CMake?