opengl-fog.rar_OPENGL fog

#include <math.h> #include <stdio.h> #include <stdlib.h> #include <GL/glut.h> #include "texture.h" #ifdef _WIN32 #define expf(x) ((float)exp((x))) #endif static int translate = 1; static float ttrans[2]; 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 animate(void) { ttrans[0] += .010f; if (ttrans[0] == 1.0f) ttrans[0] = 0.0f; ttrans[1] -= .020f; if (ttrans[1] <= 0.0f) ttrans[1] = 1.0f; glutPostRedisplay(); } void xfunc(void) { static state = 1; glutIdleFunc((state ^= 1) ? animate : NULL); } void help(void) { printf("Usage: cloudl [image]\n"); printf("'h' - help\n"); printf("'x' - toggle cloud motion\n"); printf("left mouse - pan\n"); printf("right mouse - rotate\n"); } void init(char *filename) { 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; // 从文件中获取纹理数据 if (filename) { 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 && components != 2) { printf("warning: texture should be a l or la image\n"); } if (components == 1) { int i; GLubyte *p = (GLubyte *)image; for(i = 0; i < width*height; i++) { p[i*4+3] = p[i*4+0]; } components = 2; } } // 程序自动生成纹理数据 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; } } // 纹理参数的定义 glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); 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); // 使用雾效 glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(50.,1.,.1,far_cull = 10.); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.,0.,-5.5); 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*.2 + density *.57*.2; fog_color[1] = .35*.2 + density *.45*.2; fog_color[2] = .78*.5 + density *.22*.2; 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); glLineWidth(2.0f); glEnable(GL_LINE_SMOOTH); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glPointSize(10.f); glEnable(GL_POINT_SMOOTH); glHint(GL_POINT_SMOOTH_HINT, GL_NICEST); } void draw_base(void) { glColor4f(.1, .3, .1, 1.0); glBegin(GL_QUADS); glTexCoord2f(0, 0); glVertex3f(-1.f, 0.f, -1.f); glTexCoord2f(0, 1); glVertex3f(-1.f, 0.f, 1.f); glTexCoord2f(1, 1); glVertex3f( 1.f, 0.f, 1.f); glTexCoord2f(1, 0); glVertex3f( 1.f, 0.f, -1.f); glEnd(); } void draw_runway(void) { glColor4f(.1, .1, .1, 1.0); glPushMatrix(); glScalef(.1f, 1.f, 1.f); glBegin(GL_QUADS); glTexCoord2f(0, 0); glVertex3f(-1.f, 0.f, -1.f); glTexCoord2f(0, 1); glVertex3f(-1.f, 0.f, 1.f); glTexCoord2f(1, 1); glVertex3f( 1.f, 0.f, 1.f); glTexCoord2f(1, 0); glVertex3f( 1.f, 0.f, -1.f); glEnd(); glPopMatrix(); } void quad(float x, float y, float z) { glPushMatrix(); glTranslatef(x, y, z); glRotatef(90.f, 1.f, 0.f, 0.f); glScalef(.03f, .03f, .03f); glBegin(GL_QUADS); glTexCoord2f(0, 0); glVertex3f(-1.f, 0.f, -1.f); glTexCoord2f(0, 1); glVertex3f(-1.f, 0.f, 1.f); glTexCoord2f(1, 1); glVertex3f( 1.f, 0.f, 1.f); glTexCoord2f(1, 0); glVertex3f( 1.f, 0.f, -1.f); glEnd(); glPopMatrix(); } void draw_lights(void) { int i; glEnable(GL_BLEND); glColor4f(.7f, .7f, .1f, 1.0); glPushMatrix(); glScalef(.1f, 1.f, 1.f); glEnable(GL_POINT_SMOOTH); for(i = 0; i <= 20; i++) { glPointSize((float)i/2.); glBegin(GL_POINTS); glVertex3f(-1.f, 0.f, -1.f+2.f/20*i); glVertex3f( 1.f, 0.f, -1.f+2.f/20*i); glEnd(); } glPopMatrix(); glDisable(GL_BLEND); } void draw_fog(void) { glEnable(GL_BLEND); glEnable(GL_TEXTURE_2D); glMatrixMode(GL_TEXTURE); glPushMatrix(); glTranslatef(ttrans[0], ttrans[1], 0.); glColor4f(1.f, 1.f, 1.f, 1.0); glBegin(GL_QUADS); glTexCoord2f(0, 0); glVertex3f(-1., .2, -1.); glTexCoord2f(0, 5); glVertex3f(-1., .2, 1.); glTexCoord2f(5, 5); glVertex3f( 1., .2, 1.); glTexCoord2f(5, 0); glVertex3f( 1., .2, -1.); glEnd(); glPopMatrix(); glMatrixMode(GL_MODELVIEW); glDisable(GL_TEXTURE_2D); glDisable(GL_BLEND); } 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(10,1,10); glTranslatef(0.f,-1.f,0.f); draw_base(); draw_runway(); draw_lights(); draw_fog(); 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 'x': xfunc(); break; case 'h': help(); break; case '\033': exit(EXIT_SUCCESS); break; default: break; } glutPostRedisplay(); } void visible(int state) { if (state == GLUT_VISIBLE) glutIdleFunc(animate); else glutIdleFunc(NULL); } int main(int argc, char** argv) { glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE); glutInitWindowSize(400, 300); glutInit(&argc, argv); glutCreateWindow(argv[0]); glutDisplayFunc(display); glutKeyboardFunc(key); glutReshapeFunc(reshape); glutMouseFunc(mouse); glutMotionFunc(motion); glutIdleFunc(animate); glutVisibilityFunc(visible); init(argc == 1 ? "clouds.bw" : argv[1]); glutMainLoop(); return 0; }