Hello,CG

第一个CG程序

1. 首先，自然是包含头文件

#include <cg/cg.h>
#include <cg/cgGL.h>
#pragma comment(lib,"cg.lib")
#pragma comment(lib,"cgGL.lib")

2. 创建着色器程序所需的变量

着色上下文CGcontext,着色器程序CGprogram,

CGprofile是用来告诉CG如何选择最适合你显卡的方式来处理顶点或片段着色,

CGparameter,参数传递，从你所写的程序中向着色器程序中传递参数.

static CGcontext Context = NULL;
static CGprogram VertexProgram = NULL;
static CGprofile VertexProfile;
static CGparameter KdParam = NULL;
static CGparameter ModelViewProjParam = NULL;
static CGparameter VertexColorParam = NULL;
//反射光颜色（kdParam），顶点颜色(vertexColorParam)和模型透视矩阵（modelViewProj）

3. 着色器初始化，在opengl程序的init函数中进行

Context = cgCreateContext();
VertexProfile = cgGLGetLatestProfile(CG_GL_VERTEX);
VertexProgram = cgCreateProgramFromFile(Context,CG_SOURCE, "vertexShader.cg",VertexProfile,NULL, NULL);
cgGLLoadProgram(VertexProgram);
KdParam = cgGetNamedParameter(VertexProgram, "Kd");
ModelViewProjParam = cgGetNamedParameter(VertexProgram, "ModelViewProj");
VertexColorParam = cgGetNamedParameter(VertexProgram, "IN.VertexColor");

4. 着色器的参数传入，在display函数中进行

cgGLBindProgram(VertexProgram);
cgGLSetParameter4f(KdParam, 1.0, 1.0, 0.0, 1.0);
cgGLSetStateMatrixParameter(ModelViewProjParam,CG_GL_MODELVIEW_PROJECTION_MATRIX,CG_GL_MATRIX_IDENTITY);
cgGLEnableProfile(VertexProfile);

5. 最后别忘记了释放资源

cgDestroyProgram(VertexProgram);
cgDestroyContext(Context);

完整代码如下

#include <stdio.h>
#include <gl/glut.h>
#include <cg/cg.h>
#include <cg/cgGL.h>
#pragma comment(lib,"cg.lib")
#pragma comment(lib,"cgGL.lib")

#define WINDOW_SIZE 800

static CGcontext Context = NULL;
static CGprogram VertexProgram = NULL;
static CGprofile VertexProfile;
static CGparameter KdParam = NULL;
static CGparameter ModelViewProjParam = NULL;
static CGparameter VertexColorParam = NULL;
//反射光颜色（kdParam），顶点颜色(vertexColorParam)和模型透视矩阵（modelViewProj）

GLfloat CubeNormals[6][3] =
{
    {-1.0, 0.0, 0.0}, {0.0, 1.0, 0.0}, {1.0, 0.0, 0.0},
    {0.0, -1.0, 0.0}, {0.0, 0.0, 1.0}, {0.0, 0.0, -1.0}
};
GLint CubeFaces[6][4] =
{
    {0, 1, 2, 3}, {3, 2, 6, 7}, {7, 6, 5, 4},
    {4, 5, 1, 0}, {5, 6, 2, 1}, {7, 4, 0, 3}
};
GLfloat CubeVertices[8][3];


static void InitializeCube(GLfloat v[8][3])
{
    /* Setup cube vertex data. */
    v[0][0] = v[1][0] = v[2][0] = v[3][0] = -1;
    v[4][0] = v[5][0] = v[6][0] = v[7][0] = 1;
    v[0][1] = v[1][1] = v[4][1] = v[5][1] = -1;
    v[2][1] = v[3][1] = v[6][1] = v[7][1] = 1;
    v[0][2] = v[3][2] = v[4][2] = v[7][2] = 1;
    v[1][2] = v[2][2] = v[5][2] = v[6][2] = -1;
}

static void DrawCube(void)
{
    int i;

    cgGLBindProgram(VertexProgram);
    cgGLSetParameter4f(KdParam, 1.0, 1.0, 0.0, 1.0);
    cgGLSetStateMatrixParameter(ModelViewProjParam,CG_GL_MODELVIEW_PROJECTION_MATRIX,CG_GL_MATRIX_IDENTITY);
    cgGLEnableProfile(VertexProfile);

    for(i = 0; i < 6; i++)
    {
        glBegin(GL_QUADS);
        {
            glNormal3fv(&CubeNormals[i][0]);

            cgGLSetParameter3f(VertexColorParam, 1.0, 0.0, 0.0);glVertex3fv(&CubeVertices[CubeFaces[i][0]][0]);
            cgGLSetParameter3f(VertexColorParam, 0.0, 1.0, 0.0);glVertex3fv(&CubeVertices[CubeFaces[i][1]][0]);
            cgGLSetParameter3f(VertexColorParam, 0.0, 0.0, 1.0);glVertex3fv(&CubeVertices[CubeFaces[i][2]][0]);
            cgGLSetParameter3f(VertexColorParam, 1.0, 1.0, 1.0);glVertex3fv(&CubeVertices[CubeFaces[i][3]][0]);
        }
        glEnd();
    }
    cgGLDisableProfile(VertexProfile);
}

void init()
{
    glShadeModel(GL_SMOOTH);
    glClearColor(0.0f,0.0f,0.0f,0.0f);
    glClearDepth(1.0f);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);

    glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST);

    InitializeCube(CubeVertices);


    //-------------------------------cg init-------------------------------------------------------
    Context = cgCreateContext();
    VertexProfile = cgGLGetLatestProfile(CG_GL_VERTEX);
    VertexProgram = cgCreateProgramFromFile(Context,CG_SOURCE, "vertexShader.cg",VertexProfile,NULL, NULL);
    cgGLLoadProgram(VertexProgram);
    KdParam = cgGetNamedParameter(VertexProgram, "Kd");
    ModelViewProjParam = cgGetNamedParameter(VertexProgram, "ModelViewProj");
    VertexColorParam = cgGetNamedParameter(VertexProgram, "IN.VertexColor");
}

void display()
{
    static float rotate=0.0;
    rotate+=1.0;

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();

    glTranslatef(0.0,0.0,-6.0);
    glRotatef(30,1.0,0.0,0.0);
    glRotatef(rotate,0.0,1.0,0.0);

    DrawCube();
    glutSwapBuffers();
}

void reshape(int w,int h)
{
    if (h==0) h=1;
    glViewport(0,0,w,h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f,(GLfloat)w/(GLfloat)h,0.01f,400.0f);
    glMatrixMode(GL_MODELVIEW);
}

int main(int argc,char* argv[])
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA);
    glutCreateWindow(argv[0]);
    glutReshapeWindow(WINDOW_SIZE,WINDOW_SIZE);

    glutDisplayFunc(display);
    glutIdleFunc(display);
    glutReshapeFunc(reshape);

    init();
    glutMainLoop();
    cgDestroyProgram(VertexProgram);
    cgDestroyContext(Context);
    return 0;
}