3D programming with Klimt
以OpenGL 來講, 最有名大概就是MESA LIBRARY;
而OpenGL ES則是Vincent 3D LIBRARY了, 但這套似乎主要支援wince的環境,
如果要在linux上run, 應該還要下一翻苦工. 所以我選用了可以在linux上compile的 klimt 3D Library
雖然這套宣稱不是OpenGL ES library, 但是OpenGL ES大部份的function都可以使用
而這套library 的EGL 是建構在SDL 上的, 所以在執行之前, 需先在平台上準備好你的X和SDL
#Cross compiling SDL for arm...
1. version:
arm-linux-gcc v3.4.3
SDL:SDL-1.2.13( http://www.libsdl.org/ )
2. assuming installed path is /home/jacob/test
3. configure:
./configure --build=i686 --host=arm-linux --prefix=/home/jacob/test --enable-static --enable-joystick=no --enable-cdrom=no --enable-alsa=no --disable-alsatest --enable-esd=no --disable-esdtest --enable-pulseaudio=no --enable-arts=no --enable-nas=no --enable-diskaudio=no --enable-mintaudio=no --enable-nasm=no --enable-altivec=no --enable-ipod=no --enable-video-dga=no --enable-video-photon=no --enable-video-carbon=no --enable-video-cocoa=no --enable-video-ps2gs=no --enable-video-svga=no --enable-video-xbios=no --enable-video-gem=no --enable-directx=no --enable-rpath; make; make install
4. result:
jacob@jacob-laptop:~/test/lib$ ls libSDL*
libSDL-1.2.so.0 libSDL-1.2.so.0.11.2 libSDL.a libSDL.la libSDLmain.a libSDL.so
SDL 目前安裝在/home/jacob/test裡, 下一步則是cross compiling klimt 3d library了,
不知道是不是gcc version的問題, 我必須做一些修改, 才能順利compiling
#decompressing the klimt 3d library
#Cross compiling klimt library for arm...
a. modify klimt-src-0.6.2/klimt/build/LinuxX11/Makefile:
CXXFLAGS = -g -Wall -pipe -O3 -fPIC -funroll-all-loops -D_LINUX
CXXFLAGS += -I/home/jacob/test/include -D_GNU_SOURCE=1 -D_REENTRANT # -D_USE_OLDRASTERIZER_
LFLAGS = -shared -Wl,-soname,libKlimt.so.0 -L/home/jacob/test/lib -lSDL -lpthread
LIBS = -L/home/jacob/test/lib -Wl -lSDL -lpthread -lm
b. modify klimt-src-0.6.2/klimt/src/Base/klVec3.h:
Line 127:
//#ifdef GCC_295X
friend const klVec3T operator+ (const klVec3T& left, const klVec3T& right);
friend const klVec3T operator- (const klVec3T& left, const klVec3T& right);
//#else
// friend const klVec3T operator+<> (const klVec3T& left, const klVec3T& right);
// friend const klVec3T operator-<> (const klVec3T& left, const klVec3T& right);
//#endif // GCC_2.95.X
c. modify klimt-src-0.6.2/klimt/src/Base/klVec4.h:
Line 137:
//#ifdef GCC_295X
friend const klVec4T operator+ (const klVec4T& left, const klVec4T& right);
friend const klVec4T operator- (const klVec4T& left, const klVec4T& right);
//#else
// friend const klVec4T operator+<> (const klVec4T& left, const klVec4T& right);
// friend const klVec4T operator-<> (const klVec4T& left, const klVec4T& right);
//#endif // GCC_2.95.X
d. modify klimt-src-0.6.2/klimt/src/Base/klFloat_fixed.h:
Line 164:
klFloat_fixed& operator*=(double nV) { v = MATHBASE::multiply(v, MATHBASE::fixedFromDouble(nV)); return *this; }
klFloat_fixed& operator/=(double nV) { v = MATHBASE::divide(v, MATHBASE::fixedFromDouble(nV)); return *this; }
e. cd klimt-src-0.6.2/klimt/build/LinuxX11/
make CXX=arm-linux-g++
f. ls klimt-src-0.6.2/klimt/bin/:
libKlimt.so libKlimt.so.0 libKlimt.so.0.5 libKlimt.so.0.5.0
g. cp libKlimt.so libKlimt.so.0 libKlimt.so.0.5 libKlimt.so.0.5.0 to /home/jacob/test/lib
h. cd klimt-src-0.6.2/klimt/test/simple_linux_x11
modify Makefile:
CXXFLAGS = -g -Wall -pipe -O3 -fPIC -funroll-all-loops
CXXFLAGS += -D_LINUX -I/home/jacob/test/include/SDL -I../../klimt/include
LDFLAGS = -L/home/jacob/test/lib -lKlimt -lSDL -lpthread
modify simple.cpp
1. comment "#include "glut.h" "
2. Line 116:
glutSolidCube -> klutSolidCube
make CXX=arm-linux-g++
i. copy /home/jacob/test/lib to the specify direction in the target
如此, 把剛剛編出來的klimt 和sdl library放到target上, 就可以跑一些OpenGL ES的程式啦~~
接下來, 來試試一些OpenGL ES的基本功能, 先試試畫線, 三角形以及方形,
令我訝異的是, 我無法畫點, 真不是哪裡出了錯:
My Makefile:
##
# Makefile for Unix
#
CXX = arm-linux-g++
CXXFLAGS = -g -Wall -pipe -O3 -fPIC -funroll-all-loops
CXXFLAGS += -I/home/jacob/target/opengl/include/SDL -D_GNU_SOURCE=1 -D_REENTRANT -I../../klimt/include
LDFLAGS = -lKlimt -L/home/jacob/target/opengl/lib -lSDL -lpthread -L../../bin
LIBS = -lKlimt -L/home/jacob/target/opengl/lib -Wl -lSDL -lpthread -lm
TARGET = ./sample
OBJS = sample.o load_bmp.o
$(TARGET): $(OBJS)
$(CXX) -o $(TARGET) $(LIBS) $(OBJS)
%.o: %.cpp
$(CXX) $(CXXFLAGS) -c $< -o $@
demo: demo.o
$(CXX) -o demo $(LIBS) demo.o
clean:
rm -f $(OBJS) *.o sample
Source Code:
#include stdio.h
#include stdlib.h
#include stdio.h
#include string.h
#include math.h
#include SDL.h
#include "gl/gl.h"
#include "gl/glu.h"
#include "sample.h"
#define FixedFromFloat(x) (GLfixed)( x * (1<<16))
void render()
{
int i=0;
GLfixed x,y,z;
GLfloat sizes[2];
GLfloat step;
glClearColorx( 0, 0, 0, 1 );
glColor3x( FixedFromFloat(1.0f), FixedFromFloat(1.0f), FixedFromFloat(1.0f) ); //draw green points
glShadeModel(GL_FLAT);
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
glPolygonMode(GL_BACK,GL_LINE);
glPolygonMode(GL_FRONT,GL_LINE);
glViewport(0, 0, 640, 480);
while(i<100){
/* Gl_POINTS failed, I dont know why. It draws nothing */
glBegin(GL_POINTS);
x = FixedFromFloat(0.5f);
y = FixedFromFloat(0.9f);
glVertex3x( x, y, 0);
glVertex3x( x, y+500, 0);
glEnd();
/* Draws an oblique line in the X-Y+ region. */
/* It is the same as glVertex3f( -0.5f, 0.5f, 0.3f)
in the floating system. */
glBegin(GL_LINES);
x = -FixedFromFloat(0.5f); // (1<<16)*0.5
y = FixedFromFloat(0.5f);
z = FixedFromFloat(0.3f);
glVertex3x( 0, 0, 0);
glVertex3x( x, y, z);
glEnd();
/* Draws an oblique LINE_STRIP in the X-Y- region. */
glBegin(GL_LINE_STRIP);
x = -FixedFromFloat(0.5f);
y = -FixedFromFloat(0.5f);
z = FixedFromFloat(0.3f);
glVertex3x( 0, 0, 0);
glVertex3x( x, y, z);
x = -FixedFromFloat(0.33f);
glVertex3x( x, y, z);
glEnd();
/* Draws triangles in the X+Y- region */
glBegin(GL_TRIANGLES);
x = FixedFromFloat(0.0f);
y = -FixedFromFloat(0.0f);
z = FixedFromFloat(0.0f);
glVertex3x( x, y, z);
glVertex3x( x+FixedFromFloat(0.1f), y-FixedFromFloat(0.2f), z);
glVertex3x( x+FixedFromFloat(0.2f), y, z);
glEnd();
/* Draws triangle strip in the X+Y- region */
glBegin(GL_TRIANGLE_STRIP);
x = FixedFromFloat(0.2f);
y = -FixedFromFloat(0.2f);
z = FixedFromFloat(0.0f);
glVertex3x( x, y, z);
glVertex3x( x+FixedFromFloat(0.1f), y-FixedFromFloat(0.2f), z);
glVertex3x( x+FixedFromFloat(0.2f), y, z);
glVertex3x( x+FixedFromFloat(0.3f), y-FixedFromFloat(0.2f), z);
glEnd();
/* Draws triangle strip in the X+Y+ region */
glBegin(GL_TRIANGLE_FAN);
x = FixedFromFloat(0.4f);
y = FixedFromFloat(0.4f);
z = FixedFromFloat(0.0f);
glVertex3x( x, y, z);
glVertex3x( x+FixedFromFloat(0.2f), y+FixedFromFloat(0.2f), z);
glVertex3x( x+FixedFromFloat(0.4f), y-FixedFromFloat(0.1f), z);
glVertex3x( x+FixedFromFloat(0.3f), y-FixedFromFloat(0.2f), z);
glEnd();
/* Draws a rectangle in the X-Y+ region*/
glBegin(GL_QUADS);
x = -FixedFromFloat(0.4f);
y = FixedFromFloat(0.2f);
glVertex3x( x, y, 0);
glVertex3x( x, y-FixedFromFloat(0.2f), 0);
glVertex3x( x-FixedFromFloat(0.2f), y-FixedFromFloat(0.2f), 0);
glVertex3x( x-FixedFromFloat(0.2f), y, 0);
glEnd();
//other types: GL_QUAD_STRIP, GL_POLYGON
EGLSurface surface = eglGetCurrentSurface(EGL_DRAW);
EGLDisplay display = eglGetCurrentDisplay();
eglSwapBuffers(display, surface);
i++;
}
}
int main(int argc, char *argv[])
{
SDL_Surface *screen;
SDL_Init(SDL_INIT_VIDEO);
//create egl interface
screen=SDL_SetVideoMode(640,480,16,SDL_HWSURFACE|SDL_DOUBLEBUF);
EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
EGLint major, minor;
eglInitialize(display, &major, &minor);
EGLSurface sfc = eglCreateWindowSurface(display, 0, screen, 0);
EGLContext ctx = eglCreateContext(display, 0, screen, 0);
eglMakeCurrent(display, sfc, sfc, ctx);
render();
SDL_Quit();
return 0;
}
以下是畫出來的結果:
而三角椎旋轉, 漸層色彩以及load background都正常
但是blend 功能實在是令人無法接受啊, 下圖我是想讓1個小黃色quard 和紅色的quard混合在一起
而且這套library居然不支持alpha, lighting和 frog的效果也十分不怎麼樣
不過物件texture的功能可以正常運行, 但如預期的, 只要物件一貼圖速度馬上慢了下來
一個場景應該不能畫太多elements