Add volume rendering example. (~2.3x speedup from SIMD vs serial code.)

examples/volume_rendering/Makefile

@@ -0,0 +1,38 @@
+
+ARCH = $(shell uname)
+
+TASK_CXX=tasks_pthreads.cpp
+TASK_LIB=-lpthread
+
+ifeq ($(ARCH), Darwin)
+  TASK_CXX=tasks_gcd.cpp
+  TASK_LIB=
+endif
+
+TASK_OBJ=$(addprefix objs/, $(TASK_CXX:.cpp=.o))
+
+CXX=g++ -m64
+CXXFLAGS=-Iobjs/ -O3 -Wall
+ISPC=ispc
+ISPCFLAGS=-O2 --target=sse4x2 --arch=x86-64
+
+default: volume
+
+.PHONY: dirs clean
+
+dirs:
+	/bin/mkdir -p objs/
+
+clean:
+	/bin/rm -rf objs *~ volume
+
+volume: dirs objs/volume.o objs/volume_serial.o objs/volume_ispc.o $(TASK_OBJ)
+	$(CXX) $(CXXFLAGS) -o $@ objs/volume.o objs/volume_ispc.o objs/volume_serial.o $(TASK_OBJ) -lm $(TASK_LIB)
+
+objs/%.o: %.cpp
+	$(CXX) $< $(CXXFLAGS) -c -o $@
+
+objs/volume.o: objs/volume_ispc.h 
+
+objs/%_ispc.h objs/%_ispc.o: %.ispc
+	$(ISPC) $(ISPCFLAGS) $< -o objs/$*_ispc.o -h objs/$*_ispc.h