www.pudn.com > MoveCloud.rar > CLOUD.C

#include 
#include 
#include 
#include 
#include "texture.h"

#ifdef _WIN32
#define expf(x) ((float)exp((x)))
#endif

static float ttrans[2];
static float scale = 1.;
static float transx, transy, rotx, roty;
static int ox = -1, oy = -1;
static int mot;
#define PAN	1
#define ROT	2

void pan(int x, int y)  
{
    transx +=  (x-ox)/500.;
    transy -= (y-oy)/500.;
    ox = x; oy = y;
    glutPostRedisplay();
}

void rotate(int x, int y)  
{
    rotx += x-ox;
    if (rotx > 360.) rotx -= 360.;
    else if (rotx < -360.) rotx += 360.;
    roty += y-oy;
    if (roty > 360.) roty -= 360.;
    else if (roty < -360.) roty += 360.;
    ox = x; oy = y;
    glutPostRedisplay();
}

void motion(int x, int y)  
{
    if (mot == PAN)  
		pan(x, y);
    else if (mot == ROT)  
		rotate(x,y);
}

void mouse(int button, int state, int x, int y)  
{
    if(state == GLUT_DOWN)  
	{ 
		switch(button)  
		{ 
			case GLUT_LEFT_BUTTON: 
				mot = PAN; 
				motion(ox = x, oy = y); 
				break; 
			case GLUT_RIGHT_BUTTON: 
				mot = ROT; 
				motion(ox = x, oy = y); 
				break; 
			case GLUT_MIDDLE_BUTTON: 
				break; 
		}
    }  
	else if (state == GLUT_UP)  
	{ 
		mot = 0;
    }
}

void up(void)  
{  
	scale += .1;  
}
void down(void)  
{  
	scale -= .1;  
}

void animate(void)  
{
    ttrans[0] += .01;
    if (ttrans[0] == 1.0)  
		ttrans[0] = 0;
    ttrans[1] += .005;
    if (ttrans[1] == 1.0)  
		ttrans[1] = 0;
    glutPostRedisplay();
}

void help(void)  
{
    printf("Usage: cloud [image]\n");
    printf("'h'            - help\n");
    printf("'UP'           - scale up\n");
    printf("'DOWN'         - scale down\n");
    printf("left mouse     - pan\n");
    printf("right mouse    - rotate\n");
}

void init(char *filename)  
{ 
	//  定义云彩的颜色
    GLfloat cloud_color[4] = { 1., 1., 1., 0., };
    GLfloat fog_color[4], fog_density = 0.05, density, far_cull;
    unsigned *image;
    int width, height, components; 
 
	//  如果从文件中读入纹理
    if (filename)  
	{ 
		//  读入纹理数据
		image = read_texture(filename, &width, &height, &components);
		if (image == NULL)  
		{
			fprintf(stderr, "Error: Can't load image file \"%s\".\n", filename);
			exit(EXIT_FAILURE);
		}  
		else  
		{
			printf("%d x %d image loaded\n", width, height);
		}
		if (components != 1)  
		{
			printf("warning: texture should be a bw image (single component)\n");
		}
	}  
	//  使用程序自动生成纹理 
	else  
	{
		int i, j;
		unsigned char *img;
		components = 4; width = height = 512;
		image = (unsigned *) malloc(width*height*sizeof(unsigned));
		img = (unsigned char *)image;
		for (j = 0; j < height; j++)
	    for (i = 0; i < width; i++)  
		{
			int w2 = width/2, h2 = height/2;
			if (i & 32) 
				img[4*(i+j*width)+0] = 0xff; 
			else 
				img[4*(i+j*width)+1] = 0xff; 
			if (j&32) 
				img[4*(i+j*width)+2] = 0xff; 
			if ((i-w2)*(i-w2) + (j-h2)*(j-h2) > 64*64 && (i-w2)*(i-w2) + (j-h2)*(j-h2) < 300*300)  
			img[4*(i+j*width)+3] = 0xff;
	    }

    } 
	//  定义纹理参数
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND);
    glTexEnvfv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, cloud_color);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexImage2D(GL_TEXTURE_2D, 0, components, width,
                 height, 0, GL_RGBA, GL_UNSIGNED_BYTE,
                 image);
    glEnable(GL_TEXTURE_2D);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(50.,1.,.1,far_cull = 10.);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glTranslatef(0.,0.,-5.5); 
 
	//  使用雾效
    density = 1.- expf(-5.5 * fog_density * fog_density *
			      far_cull * far_cull);
#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define MIN(a,b) ((a) < (b) ? (a) : (b))
    density = MAX(MIN(density, 1.), 0.);
    fog_color[0] = .23 + density *.57;
    fog_color[1] = .35 + density *.45;
    fog_color[2] = .78 + density *.22;
    glClearColor(fog_color[0], fog_color[1], fog_color[2], 1.f);
    glFogi(GL_FOG_MODE, GL_EXP2);
    glFogf(GL_FOG_DENSITY, fog_density);
    glFogfv(GL_FOG_COLOR, fog_color);
    if (fog_density > 0)
	glEnable(GL_FOG);
}

void display(void)  
{
    glClear(GL_COLOR_BUFFER_BIT);
    glPushMatrix();
    glTranslatef(transx, transy, 0.f);
    glRotatef(rotx, 0., 1., 0.);
    glRotatef(roty, 1., 0., 0.);
    glScalef(scale,scale,1.);
    glScalef(10,1,10);
    glColor3f(.19, .25, .70);
    glMatrixMode(GL_TEXTURE);	//  变换纹理坐标
    glPushMatrix();
    glTranslatef(ttrans[0], ttrans[1], 0.); 
	//  绘制四边形
    glBegin(GL_QUADS);
		glTexCoord2f(0, 0); glVertex3f(-1., 1., -1.);
		glTexCoord2f(0, 5); glVertex3f(-1., 1.,  1.);
		glTexCoord2f(5, 5); glVertex3f( 1., 1.,  1.);
		glTexCoord2f(5, 0); glVertex3f( 1., 1., -1.);
    glEnd();
    glPopMatrix();
    glMatrixMode(GL_MODELVIEW);
    glPopMatrix();
    glutSwapBuffers();
}

void reshape(int w, int h)  
{
    glViewport(0, 0, w, h);
}


void key(unsigned char key, int x, int y)  
{
    switch(key)  
	{ 
		case 'h':  
			help();  
			break; 
		case '\033':  
			exit(EXIT_SUCCESS);  
			break; 
		default:  
			break;
    }
    glutPostRedisplay();
}


void special(int key, int x, int y)  
{
    switch(key)  
	{ 
		case GLUT_KEY_UP:	 
			up();  
			break;
		case GLUT_KEY_DOWN:	 
			down();  
			break;
    }
}

void visible(int state)
{
    if (state == GLUT_VISIBLE) 
		glutIdleFunc(animate); 
	else 
		glutIdleFunc(NULL);
}

int main(int argc, char** argv)  
{
    glutInitWindowSize(400, 300);
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE);
    glutCreateWindow(argv[0]);
    init(argc == 1 ? "clouds.bw" : argv[1]);
    glutDisplayFunc(display);
    glutKeyboardFunc(key);
    glutSpecialFunc(special);
    glutReshapeFunc(reshape);
    glutMouseFunc(mouse);
    glutMotionFunc(motion);
    glutIdleFunc(animate);
    glutVisibilityFunc(visible);

    glutMainLoop();
    return 0;
}