demo.c

计算机图形学～想必是很多人需要的～在此共享一下

/* demo.c   */

/* Rotating cube demo*/
/* demonstrates many OpenGL features including */
/* smooth shading, antialiasing, texture mapping, */
/* color interpolation */

/* uses a trackball interface */

/* E. Angel, Interactive Computer Graphics */
/* A Top-Down Approach with OpenGL, Third Edition */
/* Addison-Wesley Longman, 2003 */


/* Prints out instructions */

/*Both normals and colors are assigned to the vertices */
/*Cube is centered at origin so (unnormalized) normals
are the same as the vertex values */

#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>
#include <GL/glu.h>

#define bool int
#define false 0
#define true 1
#define M_PI 3.14159

/*
** Global settings controlled by keyboard input.
*/
bool texEnabled 		= false;
bool mipmapEnabled 		= false;
bool fastTexture 		= true;
bool fogEnabled 		= false;
bool depthEnabled 		= true;
bool lineAAEnabled 		= false;
bool lightingEnabled 		= false;
bool smoothEnabled 		= false;
bool drawLines 			= true;
bool idleSpin 			= true;
bool perspectiveXform 		= false;

/*
** Global settings.
*/

float 	nnear = 3.0;    	/* near clipping plane in eye coords */
float 	nfar = 7.0;    	/* far clipping plane in eye coords */
float 	viewxform_z = -5.0;

int 	winWidth, winHeight;

float 	angle = 0.0, axis[3], trans[3];
bool 	trackballEnabled = true;
bool 	trackballMove = false;
bool 	trackingMouse = false;
bool 	redrawContinue = false;

GLfloat lightXform[4][4] = {
    {1.0, 0.0, 0.0, 0.0},
    {0.0, 1.0, 0.0, 0.0},
    {0.0, 0.0, 1.0, 0.0},
    {0.0, 0.0, 0.0, 1.0}
};
GLfloat objectXform[4][4] = {
    {1.0, 0.0, 0.0, 0.0},
    {0.0, 1.0, 0.0, 0.0},
    {0.0, 0.0, 1.0, 0.0},
    {0.0, 0.0, 0.0, 1.0}
};
GLfloat *trackballXform = (GLfloat*)objectXform;

void display(void);
void spinCube(void);
void setMenuEntries(bool);

/*----------------------------------------------------------------------*/
/* 
** Materials setup.
*/
typedef struct materialStruct {
   GLfloat ambient[4];
   GLfloat diffuse[4];
   GLfloat specular[4];
   GLfloat shininess;
} materialStruct;

materialStruct brassMaterials = {
    {0.33F, 0.22F, 0.03F, 1.0F},
    {0.78F, 0.57F, 0.11F, 1.0F},
    {0.99F, 0.91F, 0.81F, 1.0F},
    27.8F
};
materialStruct redPlasticMaterials = {
    {0.3F, 0.0F, 0.0F, 1.0F},
    {0.6F, 0.0F, 0.0F, 1.0F},
    {0.8F, 0.6F, 0.6F, 1.0F},
    32.0F
};
materialStruct colorCubeMaterials = {
    { 1.0F, 1.0F, 1.0F, 1.0F },
    { 1.0F, 1.0F, 1.0F, 1.0F },
    { 1.0F, 1.0F, 1.0F, 1.0F },
    {100.0F}
};

materialStruct *currentMaterials = &redPlasticMaterials;

void materials( materialStruct *materials)
{
    /* define material proerties for front face of all polygons */
    glMaterialfv(GL_FRONT, GL_AMBIENT, materials->ambient);
    glMaterialfv(GL_FRONT, GL_DIFFUSE, materials->diffuse);
    glMaterialfv(GL_FRONT, GL_SPECULAR, materials->specular);
    glMaterialf(GL_FRONT, GL_SHININESS, materials->shininess);
}

/*----------------------------------------------------------------------*/
/*
** Lighting setup.
*/
typedef struct lightingStruct {
    GLfloat ambient[4];
    GLfloat diffuse[4];
    GLfloat specular[4];
} lightingStruct;

lightingStruct whiteLighting = {
    {0.0F, 0.0F, 0.0F, 1.0F},
    {1.0F, 1.0F, 1.0F, 1.0F},
    {1.0F, 1.0F, 1.0F, 1.0F}
};
lightingStruct colorCubeLighting = {
    {0.2F, 0.0F, 0.0F, 1.0F},
    {0.0F, 1.0F, 0.0F, 1.0F},
    {0.0F, 0.0F, 1.0F, 1.0F}
};

lightingStruct *currentLighting = &whiteLighting;

void lighting(lightingStruct *lightSettings)
{
    /* set up light 0 ambient, diffuse, specular, and spotlight */

    glLightfv(GL_LIGHT0, GL_AMBIENT, lightSettings->ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, lightSettings->diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, lightSettings->specular);

    glLightf(GL_LIGHT0, GL_SPOT_EXPONENT, 0.0F);
    glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, 180.0F);
    glLightf(GL_LIGHT0, GL_CONSTANT_ATTENUATION, 1.0F);
    glLightf(GL_LIGHT0, GL_LINEAR_ATTENUATION, 0.0F);
    glLightf(GL_LIGHT0, GL_QUADRATIC_ATTENUATION, 0.0F);

    glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_TRUE);
}

/*----------------------------------------------------------------------*/
/*
** Light position setup.
*/
void setLightPos()
{
    GLfloat light0_pos[4] = { 0.90F, 0.90F, 2.25F, 0.00F };
    GLfloat light0_spotDir[3] = {0.0F, 0.0F, -1.0F};

    glLightfv(GL_LIGHT0, GL_POSITION, light0_pos);
    glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, light0_spotDir);
}

/*----------------------------------------------------------------------*/
/*
** Initial texture settings.
*/
void texture()
{
   GLubyte image[64][64][3];
   int i, j, r, c;
   for(i=0;i<64;i++)
   {
      for(j=0;j<64;j++)
      {
	 c = ((((i&0x8)==0)^((j&0x8))==0))*255;
	 image[i][j][0]= (GLubyte) c;
	 image[i][j][1]= (GLubyte) c;
	 image[i][j][2]= (GLubyte) c;
      }
   }
   glPixelStorei(GL_UNPACK_ALIGNMENT,1);
   glTexImage2D(GL_TEXTURE_2D,0,3,64,64,0,GL_RGB,GL_UNSIGNED_BYTE, image);
   glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP);
   glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP);
   glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
   glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
   gluBuild2DMipmaps(GL_TEXTURE_2D,3,64,64,GL_RGB,GL_UNSIGNED_BYTE, image);
}

/*
** Set initial state.
*/
void initSettings(void)
{
    texture();
    glLineWidth(3.0);
    setMenuEntries(true);
}

/*----------------------------------------------------------------------*/
/*
** Set state according to user interaction.
*/
void userSettings(void) 
{
    lighting(currentLighting);
    materials(currentMaterials);

    if (lightingEnabled) {
	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
    } else {
	glDisable(GL_LIGHTING);
	glDisable(GL_LIGHT0);
    }

    if (smoothEnabled) {
	glShadeModel(GL_SMOOTH);
    } else {
	glShadeModel(GL_FLAT);
    }

    if(idleSpin) {
        glutIdleFunc(spinCube);
    } else {
	glutIdleFunc(NULL);
    }
    if (texEnabled) {
	glEnable(GL_TEXTURE_2D);
    } else {
	glDisable(GL_TEXTURE_2D);
    }
    if (fastTexture) {
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);
    } else {
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
    }
    if (mipmapEnabled) {
	glTexParameterf(GL_TEXTURE_2D,
	    GL_TEXTURE_MIN_FILTER,GL_NEAREST_MIPMAP_NEAREST);
    } else {
	glTexParameterf(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
    }

    if (fogEnabled) {

	float fogColor[] = {0.7, 0.6, 0.6, 1.0};

	glClearColor(fogColor[0], fogColor[1], fogColor[2], fogColor[3]);
	glEnable(GL_FOG);
	glFogi(GL_FOG_MODE, GL_LINEAR);
	glFogf(GL_FOG_DENSITY, 1.0);
	glFogf(GL_FOG_START, nnear);
	glFogf(GL_FOG_END, nfar);
	glFogfv(GL_FOG_COLOR, fogColor);

    } else {
	glDisable(GL_FOG);
	glClearColor(0.0,0.0,0.0,1.0);
    }

    if (lineAAEnabled) {
	glEnable(GL_BLEND);
    } else {
	glDisable(GL_BLEND);
    }

    if (lineAAEnabled) {
	glEnable(GL_LINE_SMOOTH);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    } else {
	glDisable(GL_LINE_SMOOTH);
    }

    if (depthEnabled) {
	glEnable(GL_DEPTH_TEST); /* Enable hidden--surface--removal */
    } else {
	glDisable(GL_DEPTH_TEST);
    }

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    if(perspectiveXform) {
	glFrustum(-1.25, 1.25, -1.25, 1.25, nnear, nfar);
	viewxform_z = -5.0;
    } else {
	glOrtho(-2.0, 2.0, -2.0, 2.0, nnear, nfar);
	viewxform_z = -5.0;
    }
    glMatrixMode(GL_MODELVIEW);
}

/*----------------------------------------------------------------------*/
/*
** Draw the cube.
*/
GLfloat vertices[][3] = {
    {-1.0,-1.0,-1.0},{1.0,-1.0,-1.0}, {1.0,1.0,-1.0}, {-1.0,1.0,-1.0}, 
    {-1.0,-1.0,1.0}, {1.0,-1.0,1.0}, {1.0,1.0,1.0}, {-1.0,1.0,1.0}
};

GLfloat normals[][3] = {
    {-1.0,-1.0,-1.0},{1.0,-1.0,-1.0}, {1.0,1.0,-1.0}, {-1.0,1.0,-1.0}, 
    {-1.0,-1.0,1.0}, {1.0,-1.0,1.0}, {1.0,1.0,1.0}, {-1.0,1.0,1.0}
};

GLfloat fnormals[][3] = {
    { 0.0, 0.0,-1.0}, { 0.0, 1.0, 0.0}, {-1.0, 0.0, 0.0},
    { 1.0, 0.0, 0.0}, { 0.0, 0.0, 1.0}, { 0.0,-1.0, 0.0}
};

GLfloat colors[][3] = {
    {0.0,0.0,0.0},{1.0,0.0,0.0}, {1.0,1.0,0.0}, {0.0,1.0,0.0}, 
    {0.0,0.0,1.0}, {1.0,0.0,1.0}, {1.0,1.0,1.0}, {0.0,1.0,1.0}
};


void polygon(int a, int b, int c , int d, int face)
{

    /* draw a polygon via list of vertices */

    if(drawLines) {
        glColor3f(1.0,1.0,1.0);
        glBegin(GL_LINE_LOOP);
  	glVertex3fv(vertices[a]);
  	glVertex3fv(vertices[b]);
  	glVertex3fv(vertices[c]);
  	glVertex3fv(vertices[d]);
        glEnd();
    }
    else {