smoother.c

OpeNGL超级宝典源代码. OpeNGL超级宝典源代码.

// Smoother.c
// OpenGL SuperBible
// Demonstrates point, line, and polygon smoothing
// Program by Richard S. Wright Jr.
#include "../../Common/OpenGLSB.h"	// System and OpenGL Stuff
#include "../../Common/GLTools.h"       // OpenGL Tools library
#include <math.h>


// Array of small stars
#define SMALL_STARS 100
GLTVector2  vSmallStars[SMALL_STARS];

#define MEDIUM_STARS   40
GLTVector2 vMediumStars[MEDIUM_STARS];

#define LARGE_STARS 15
GLTVector2 vLargeStars[LARGE_STARS];

#define SCREEN_X    800
#define SCREEN_Y    600

///////////////////////////////////////////////////////////////////////
// Reset flags as appropriate in response to menu selections
void ProcessMenu(int value)
    {
    switch(value)
        {
        case 1:
            // Turn on antialiasing, and give hint to do the best
            // job possible.
            glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
            glEnable(GL_BLEND);
            glEnable(GL_POINT_SMOOTH);
            glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);
            glEnable(GL_LINE_SMOOTH);
            glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
            glEnable(GL_POLYGON_SMOOTH);
            glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
            break;

        case 2:
            // Turn off blending and all smoothing
            glDisable(GL_BLEND);
            glDisable(GL_LINE_SMOOTH);
            glDisable(GL_POINT_SMOOTH);
            glDisable(GL_POLYGON_SMOOTH);
            break;

        default:
            break;
        }
        
    // Trigger a redraw
    glutPostRedisplay();
    }


///////////////////////////////////////////////////
// Called to draw scene
void RenderScene(void)
    {
    int i;                  // Loop variable
    GLfloat x = 700.0f;     // Location and radius of moon
    GLfloat y = 500.0f;
    GLfloat r = 50.0f;
    GLfloat angle = 0.0f;   // Another looping variable
		        
    // Clear the window
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
         
    // Everything is white
    glColor3f(1.0f, 1.0f, 1.0f);
    
    // Draw small stars
    glPointSize(1.0f);
    glBegin(GL_POINTS);
        for(i = 0; i < SMALL_STARS; i++)
            glVertex2fv(vSmallStars[i]);
    glEnd();
        
    // Draw medium sized stars
    glPointSize(3.05f);
    glBegin(GL_POINTS);
        for(i = 0; i< MEDIUM_STARS; i++)
            glVertex2fv(vMediumStars[i]);
    glEnd();
        
    // Draw largest stars
    glPointSize(5.5f);
    glBegin(GL_POINTS);
        for(i = 0; i < LARGE_STARS; i++)
            glVertex2fv(vLargeStars[i]);
    glEnd();
        
    // Draw the "moon"
    glBegin(GL_TRIANGLE_FAN);
        glVertex2f(x, y);
        for(angle = 0; angle < 2.0f * 3.141592f; angle += 0.1f)
            glVertex2f(x + (float)cos(angle) * r, y + (float)sin(angle) * r);
            glVertex2f(x + r, y);
    glEnd();

    // Draw distant horizon
    glLineWidth(3.5);
    glBegin(GL_LINE_STRIP);
        glVertex2f(0.0f, 25.0f);
        glVertex2f(50.0f, 100.0f);
        glVertex2f(100.0f, 25.0f);
        glVertex2f(225.0f, 125.0f);
        glVertex2f(300.0f, 50.0f);
        glVertex2f(375.0f, 100.0f);
        glVertex2f(460.0f, 25.0f);
        glVertex2f(525.0f, 100.0f);
        glVertex2f(600.0f, 20.0f);
        glVertex2f(675.0f, 70.0f);
        glVertex2f(750.0f, 25.0f);
        glVertex2f(800.0f, 90.0f);    
    glEnd();


    // Swap buffers
    glutSwapBuffers();
    }


// This function does any needed initialization on the rendering
// context. 
void SetupRC()
    {
    int i;
        
    // Populate star list
    for(i = 0; i < SMALL_STARS; i++)
        {
        vSmallStars[i][0] = (GLfloat)(rand() % SCREEN_X);
        vSmallStars[i][1] = (GLfloat)(rand() % (SCREEN_Y - 100))+100.0f;
        }
            
    // Populate star list
    for(i = 0; i < MEDIUM_STARS; i++)
        {
        vMediumStars[i][0] = (GLfloat)(rand() % SCREEN_X * 10)/10.0f;
        vMediumStars[i][1] = (GLfloat)(rand() % (SCREEN_Y - 100))+100.0f;
        }

    // Populate star list
    for(i = 0; i < LARGE_STARS; i++)
        {
        vLargeStars[i][0] = (GLfloat)(rand() % SCREEN_X*10)/10.0f;
        vLargeStars[i][1] = (GLfloat)(rand() % (SCREEN_Y - 100)*10.0f)/ 10.0f +100.0f;
        }
            
            
    // Black background
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f );

    // Set drawing color to white
    glColor3f(0.0f, 0.0f, 0.0f);
    }



void ChangeSize(int w, int h)
    {
    // Prevent a divide by zero
    if(h == 0)
        h = 1;

    // Set Viewport to window dimensions
    glViewport(0, 0, w, h);

    // Reset projection matrix stack
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    // Establish clipping volume (left, right, bottom, top, near, far)
    gluOrtho2D(0.0, SCREEN_X, 0.0, SCREEN_Y);


    // Reset Model view matrix stack
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    }

int main(int argc, char* argv[])
	{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowSize(800, 600);
	glutCreateWindow("Smoothing Out The Jaggies");
	
	// Create the Menu
	glutCreateMenu(ProcessMenu);
	glutAddMenuEntry("Antialiased Rendering",1);
	glutAddMenuEntry("Normal Rendering",2);
	glutAttachMenu(GLUT_RIGHT_BUTTON);
	
	glutReshapeFunc(ChangeSize);
	glutDisplayFunc(RenderScene);
	SetupRC();
	glutMainLoop();

	return 0;
	}