shadow.c

OpeNGL超级宝典源代码. OpeNGL超级宝典源代码.

// Shadow.c
// OpenGL SuperBible
// Demonstrates simple planar shadows
// Program by Richard S. Wright Jr.

#include "../../Common/OpenGLSB.h"	// System and OpenGL Stuff
#include "../../Common/gltools.h"       // gltools library

// Rotation amounts
static GLfloat xRot = 0.0f;
static GLfloat yRot = 0.0f;

// These values need to be available globally
// Light values and coordinates
GLfloat  ambientLight[] = { 0.3f, 0.3f, 0.3f, 1.0f };
GLfloat  diffuseLight[] = { 0.7f, 0.7f, 0.7f, 1.0f };
GLfloat  specular[] = { 1.0f, 1.0f, 1.0f, 1.0f};
GLfloat	 lightPos[] = { -75.0f, 150.0f, -50.0f, 0.0f };
GLfloat  specref[] =  { 1.0f, 1.0f, 1.0f, 1.0f };

// Transformation matrix to project shadow
GLTMatrix shadowMat;


////////////////////////////////////////////////
// This function just specifically draws the jet
void DrawJet(int nShadow)
	{
	GLTVector3 vNormal;	// Storeage for calculated surface normal

	// Nose Cone /////////////////////////////
	// Set material color, note we only have to set to black
	// for the shadow once
	if(nShadow == 0)
           glColor3ub(128, 128, 128);
	else
            glColor3ub(0,0,0);


	// Nose Cone - Points straight down
	glBegin(GL_TRIANGLES);
                glNormal3f(0.0f, -1.0f, 0.0f);
		glNormal3f(0.0f, -1.0f, 0.0f);
		glVertex3f(0.0f, 0.0f, 60.0f);
		glVertex3f(-15.0f, 0.0f, 30.0f);
		glVertex3f(15.0f,0.0f,30.0f);
                
	
                // Verticies for this panel
                {
                GLTVector3 vPoints[3] = {{ 15.0f, 0.0f,  30.0f},
                                        { 0.0f,  15.0f, 30.0f},
                                        { 0.0f,  0.0f,  60.0f}};

                // Calculate the normal for the plane
                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
		glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }	


                {
                GLTVector3 vPoints[3] = {{ 0.0f, 0.0f, 60.0f },
                                        { 0.0f, 15.0f, 30.0f },
                                        { -15.0f, 0.0f, 30.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }


                // Body of the Plane ////////////////////////
                {
                GLTVector3 vPoints[3] = {{ -15.0f, 0.0f, 30.0f },
                                        { 0.0f, 15.0f, 30.0f },
				        { 0.0f, 0.0f, -56.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                	
                {
                GLTVector3 vPoints[3] = {{ 0.0f, 0.0f, -56.0f },
                                        { 0.0f, 15.0f, 30.0f },
                                        { 15.0f,0.0f,30.0f }};
	
                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                		
    
		glNormal3f(0.0f, -1.0f, 0.0f);
		glVertex3f(15.0f,0.0f,30.0f);
		glVertex3f(-15.0f, 0.0f, 30.0f);
		glVertex3f(0.0f, 0.0f, -56.0f);
    
                ///////////////////////////////////////////////
                // Left wing
                // Large triangle for bottom of wing
                {
                GLTVector3 vPoints[3] = {{ 0.0f,2.0f,27.0f },
                                        { -60.0f, 2.0f, -8.0f },
                                        { 60.0f, 2.0f, -8.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                        	
                {
                GLTVector3 vPoints[3] = {{ 60.0f, 2.0f, -8.0f},
					{0.0f, 7.0f, -8.0f},
					{0.0f,2.0f,27.0f }};
                
                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                {
                GLTVector3 vPoints[3] = {{60.0f, 2.0f, -8.0f},
					{-60.0f, 2.0f, -8.0f},
					{0.0f,7.0f,-8.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                {
                GLTVector3 vPoints[3] = {{0.0f,2.0f,27.0f},
                                        {0.0f, 7.0f, -8.0f},
                                        {-60.0f, 2.0f, -8.0f}};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                        
                // Tail section///////////////////////////////
                // Bottom of back fin
		glNormal3f(0.0f, -1.0f, 0.0f);
		glVertex3f(-30.0f, -0.50f, -57.0f);
		glVertex3f(30.0f, -0.50f, -57.0f);
		glVertex3f(0.0f,-0.50f,-40.0f);

                {
                GLTVector3 vPoints[3] = {{ 0.0f,-0.5f,-40.0f },
					{30.0f, -0.5f, -57.0f},
					{0.0f, 4.0f, -57.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                        
                {
                GLTVector3 vPoints[3] = {{ 0.0f, 4.0f, -57.0f },
					{ -30.0f, -0.5f, -57.0f },
					{ 0.0f,-0.5f,-40.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }


                {
                GLTVector3 vPoints[3] = {{ 30.0f,-0.5f,-57.0f },
					{ -30.0f, -0.5f, -57.0f },
					{ 0.0f, 4.0f, -57.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                {
                GLTVector3 vPoints[3] = {{ 0.0f,0.5f,-40.0f },
					{ 3.0f, 0.5f, -57.0f },
					{ 0.0f, 25.0f, -65.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                        
                {
                GLTVector3 vPoints[3] = {{ 0.0f, 25.0f, -65.0f },
					{ -3.0f, 0.5f, -57.0f},
					{ 0.0f,0.5f,-40.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                {
                GLTVector3 vPoints[3] = {{ 3.0f,0.5f,-57.0f },
					{ -3.0f, 0.5f, -57.0f },
					{ 0.0f, 25.0f, -65.0f }};

                gltGetNormalVector(vPoints[0], vPoints[1], vPoints[2], vNormal);
                glNormal3fv(vNormal);
		glVertex3fv(vPoints[0]);
		glVertex3fv(vPoints[1]);
		glVertex3fv(vPoints[2]);
                }
                
                
        glEnd();
	}

// Called to draw scene
void RenderScene(void)
    {
    // Clear the window with current clearing color
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // Draw the ground, we do manual shading to a darker green
    // in the background to give the illusion of depth
    glBegin(GL_QUADS);
        glColor3ub(0,32,0);
        glVertex3f(400.0f, -150.0f, -200.0f);
        glVertex3f(-400.0f, -150.0f, -200.0f);
        glColor3ub(0,255,0);
        glVertex3f(-400.0f, -150.0f, 200.0f);
        glVertex3f(400.0f, -150.0f, 200.0f);
    glEnd();

    // Save the matrix state and do the rotations
    glPushMatrix();

    // Draw jet at new orientation, put light in correct position
    // before rotating the jet
    glEnable(GL_LIGHTING);
    glLightfv(GL_LIGHT0,GL_POSITION,lightPos);
    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
    glRotatef(yRot, 0.0f, 1.0f, 0.0f);

    DrawJet(0);

    // Restore original matrix state
    glPopMatrix();	


    // Get ready to draw the shadow and the ground
    // First disable lighting and save the projection state
    glDisable(GL_DEPTH_TEST);
    glDisable(GL_LIGHTING);
    glPushMatrix();

    // Multiply by shadow projection matrix
    glMultMatrixf((GLfloat *)shadowMat);

    // Now rotate the jet around in the new flattend space
    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
    glRotatef(yRot, 0.0f, 1.0f, 0.0f);

    // Pass true to indicate drawing shadow
    DrawJet(1);	

    // Restore the projection to normal
    glPopMatrix();

    // Draw the light source
    glPushMatrix();
    glTranslatef(lightPos[0],lightPos[1], lightPos[2]);
    glColor3ub(255,255,0);
    glutSolidSphere(5.0f,10,10);
    glPopMatrix();

    // Restore lighting state variables
    glEnable(GL_DEPTH_TEST);

    // Display the results
    glutSwapBuffers();
    }

// This function does any needed initialization on the rendering
// context. 
void SetupRC()
    {
    // Any three points on the ground (counter clockwise order)
    GLTVector3 points[3] = {{ -30.0f, -149.0f, -20.0f },
                            { -30.0f, -149.0f, 20.0f },
                            { 40.0f, -149.0f, 20.0f }};

    glEnable(GL_DEPTH_TEST);	// Hidden surface removal
    glFrontFace(GL_CCW);		// Counter clock-wise polygons face out
    glEnable(GL_CULL_FACE);		// Do not calculate inside of jet

    // Setup and enable light 0
    glLightfv(GL_LIGHT0,GL_AMBIENT,ambientLight);
    glLightfv(GL_LIGHT0,GL_DIFFUSE,diffuseLight);
    glLightfv(GL_LIGHT0,GL_SPECULAR,specular);
    glLightfv(GL_LIGHT0,GL_POSITION,lightPos);
    glEnable(GL_LIGHT0);

    // Enable color tracking
    glEnable(GL_COLOR_MATERIAL);
	
    // Set Material properties to follow glColor values
    glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);

    // All materials hereafter have full specular reflectivity
    // with a high shine
    glMaterialfv(GL_FRONT, GL_SPECULAR,specref);
    glMateriali(GL_FRONT,GL_SHININESS,128);

    // Light blue background
    glClearColor(0.0f, 0.0f, 1.0f, 1.0f );

    // Calculate projection matrix to draw shadow on the ground
    gltMakeShadowMatrix(points, lightPos, shadowMat);
    }

void SpecialKeys(int key, int x, int y)
    {
    if(key == GLUT_KEY_UP)
        xRot-= 5.0f;

    if(key == GLUT_KEY_DOWN)
        xRot += 5.0f;

    if(key == GLUT_KEY_LEFT)
        yRot -= 5.0f;

    if(key == GLUT_KEY_RIGHT)
        yRot += 5.0f;

    if(key > 356.0f)
        xRot = 0.0f;

    if(key < -1.0f)
        xRot = 355.0f;

    if(key > 356.0f)
        yRot = 0.0f;

    if(key < -1.0f)
        yRot = 355.0f;

    // Refresh the Window
    glutPostRedisplay();
    }


void ChangeSize(int w, int h)
    {
    GLfloat fAspect;

    // Prevent a divide by zero
    if(h == 0)
        h = 1;

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

    // Reset coordinate system
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    fAspect = (GLfloat)w/(GLfloat)h;
    gluPerspective(60.0f, fAspect, 200.0, 500.0);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    // Move out Z axis so we can see everything
    glTranslatef(0.0f, 0.0f, -400.0f);
    glLightfv(GL_LIGHT0,GL_POSITION,lightPos);
    }

int main(int argc, char* argv[])
    {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(800, 600);
    glutCreateWindow("Shadow");
    glutReshapeFunc(ChangeSize);
    glutSpecialFunc(SpecialKeys);
    glutDisplayFunc(RenderScene);
    SetupRC();
    glutMainLoop();

    return 0;
    }