3D programming with Klimt

来源：互联网发布：北京理工大学知乎编辑：程序博客网时间：2024/05/21 11:25

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 -lmb. modify klimt-src-0.6.2/klimt/src/Base/klVec3.h:    Line 127:      //#ifdef GCC_295Xfriend 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.Xc. 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.Xd. 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/libh. 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-loopsCXXFLAGS += -I/home/jacob/target/opengl/include/SDL -D_GNU_SOURCE=1 -D_REENTRANT  -I../../klimt/includeLDFLAGS  = -lKlimt -L/home/jacob/target/opengl/lib  -lSDL -lpthread -L../../binLIBS     = -lKlimt -L/home/jacob/target/opengl/lib -Wl  -lSDL -lpthread -lmTARGET = ./sampleOBJS = 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.oclean: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:
klimt1

而三角椎旋轉, 漸層色彩以及load background都正常
klimt3
klimt2
klimt4
klimt5

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
klimt6

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