block.c

opengl 初级学习的一个经典

	switch(nStep)
		{
		// Just draw the wire framed cube
		case 0:
			glutWireCube(50.0f);
			break;

		// Same wire cube with hidden line removal simulated
		case 1:
			// Front Face (before rotation)
			glBegin(GL_LINES);
				glVertex3f(25.0f,25.0f,25.0f);
				glVertex3f(25.0f,-25.0f,25.0f);
				
				glVertex3f(25.0f,-25.0f,25.0f);
				glVertex3f(-25.0f,-25.0f,25.0f);

				glVertex3f(-25.0f,-25.0f,25.0f);
				glVertex3f(-25.0f,25.0f,25.0f);

				glVertex3f(-25.0f,25.0f,25.0f);
				glVertex3f(25.0f,25.0f,25.0f);
			glEnd();

			// Top of cube
			glBegin(GL_LINES);
				// Front Face
				glVertex3f(25.0f,25.0f,25.0f);
				glVertex3f(25.0f,25.0f,-25.0f);
				
				glVertex3f(25.0f,25.0f,-25.0f);
				glVertex3f(-25.0f,25.0f,-25.0f);

				glVertex3f(-25.0f,25.0f,-25.0f);
				glVertex3f(-25.0f,25.0f,25.0f);

				glVertex3f(-25.0f,25.0f,25.0f);
				glVertex3f(25.0f,25.0f,25.0f);
			glEnd();

			// Last two segments for effect
			glBegin(GL_LINES);
				glVertex3f(25.0f,25.0f,-25.0f);
				glVertex3f(25.0f,-25.0f,-25.0f);

				glVertex3f(25.0f,-25.0f,-25.0f);
				glVertex3f(25.0f,-25.0f,25.0f);
			glEnd();
		
			break;

		// Uniform colored surface, looks 2D and goofey
		case 2:
			glutSolidCube(50.0f);
			break;

		case 3:
			glutSolidCube(50.0f);
			break;

		// Draw a shadow with some lighting
		case 4:
			glGetFloatv(GL_MODELVIEW_MATRIX, (GLfloat *) cubeXform);
			glutSolidCube(50.0f);
			glPopMatrix();

			// Disable lighting, we'll just draw the shadow as black
			glDisable(GL_LIGHTING);
			
			glPushMatrix();

			MakeShadowMatrix(ground, lightpos, cubeXform);
			glMultMatrixf((GLfloat *)cubeXform);
			
			glTranslatef(-10.0f, 0.0f, 10.0f);			
			
			// Set drawing color to Black
			glColor3f(0.0f, 0.0f, 0.0f);

			glutSolidCube(50.0f);
			break;

		case 5:
			glColor3ub(255,255,255);
			glGetFloatv(GL_MODELVIEW_MATRIX, (GLfloat *) cubeXform);

			// Front Face (before rotation)
			glBindTexture(GL_TEXTURE_2D, textures[1]);
			glBegin(GL_QUADS);
				glTexCoord2f(1.0f, 1.0f);
				glVertex3f(25.0f,25.0f,25.0f);
				glTexCoord2f(1.0f, 0.0f);
				glVertex3f(25.0f,-25.0f,25.0f);
				glTexCoord2f(0.0f, 0.0f);
				glVertex3f(-25.0f,-25.0f,25.0f);
				glTexCoord2f(0.0f, 1.0f);
				glVertex3f(-25.0f,25.0f,25.0f);
			glEnd();

			// Top of cube
			glBindTexture(GL_TEXTURE_2D, textures[2]);
			glBegin(GL_QUADS);
				// Front Face
				glTexCoord2f(0.0f, 0.0f);
				glVertex3f(25.0f,25.0f,25.0f);
				glTexCoord2f(1.0f, 0.0f);
				glVertex3f(25.0f,25.0f,-25.0f);
				glTexCoord2f(1.0f, 1.0f);
				glVertex3f(-25.0f,25.0f,-25.0f);
				glTexCoord2f(0.0f, 1.0f);
				glVertex3f(-25.0f,25.0f,25.0f);
			glEnd();

			// Last two segments for effect
			glBindTexture(GL_TEXTURE_2D, textures[3]);
			glBegin(GL_QUADS);
				glTexCoord2f(1.0f, 1.0f);
				glVertex3f(25.0f,25.0f,-25.0f);
				glTexCoord2f(1.0f, 0.0f);
				glVertex3f(25.0f,-25.0f,-25.0f);
				glTexCoord2f(0.0f, 0.0f);
				glVertex3f(25.0f,-25.0f,25.0f);
				glTexCoord2f(0.0f, 1.0f);
				glVertex3f(25.0f,25.0f,25.0f);
			glEnd();
		

			glPopMatrix();

			// Disable lighting, we'll just draw the shadow as black
			glDisable(GL_LIGHTING);
			glDisable(GL_TEXTURE_2D);
			
			glPushMatrix();

			MakeShadowMatrix(ground, lightpos, cubeXform);
			glMultMatrixf((GLfloat *)cubeXform);
			
			glTranslatef(-10.0f, 0.0f, 10.0f);			
			
			// Set drawing color to Black
			glColor3f(0.0f, 0.0f, 0.0f);
			glutSolidCube(50.0f);
			break;
			
		}

	glPopMatrix();

	// Flush drawing commands
	glutSwapBuffers();
	}

// This function does any needed initialization on the rendering
// context. 
void SetupRC()
	{
    BYTE *pBytes;
    int nWidth, nHeight;

	// Black background
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f );

    glTexEnvi(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE, GL_MODULATE);

	// Load the texture objects
	pBytes = gltReadBMPBits("floor.bmp", &nWidth, &nHeight);
    glBindTexture(GL_TEXTURE_2D, textures[0]);
	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,GL_RGB8,nWidth, nHeight, 0,
		GL_BGR_EXT, GL_UNSIGNED_BYTE, pBytes);
	free(pBytes);

	pBytes = gltReadBMPBits("block4.bmp", &nWidth, &nHeight);
    glBindTexture(GL_TEXTURE_2D, textures[1]);
	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,GL_RGB8,nWidth, nHeight, 0,
		GL_BGR_EXT, GL_UNSIGNED_BYTE, pBytes);
	free(pBytes);

	pBytes = gltReadBMPBits("block5.bmp", &nWidth, &nHeight);
    glBindTexture(GL_TEXTURE_2D, textures[2]);
	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,GL_RGB8,nWidth, nHeight, 0,
		GL_BGR_EXT, GL_UNSIGNED_BYTE, pBytes);
	free(pBytes);

	pBytes = gltReadBMPBits("block6.bmp", &nWidth, &nHeight);
    glBindTexture(GL_TEXTURE_2D, textures[3]);
	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,GL_RGB8,nWidth, nHeight, 0,
		GL_BGR_EXT, GL_UNSIGNED_BYTE, pBytes);
	free(pBytes);
	}

void KeyPressFunc(unsigned char key, int x, int y)
	{
	if(key == 32)
		{
		nStep++;

		if(nStep > 5)
			nStep = 0;
		}

	// Refresh the Window
	glutPostRedisplay();
	}


void ChangeSize(int w, int h)
	{
	// Calculate new clipping volume
	GLfloat windowWidth;
	GLfloat windowHeight;

	// Prevent a divide by zero, when window is too short
	// (you cant make a window of zero width).
	if(h == 0)
		h = 1;

	// Keep the square square
	if (w <= h) 
		{
		windowHeight = 100.0f*h/w;
		windowWidth = 100.0f;
		}
    else 
		{
		windowWidth = 100.0f*w/h;
		windowHeight = 100.0f;
		}


	// Reset the coordinate system before modifying
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	
	// Set the viewport to be the entire window
    glViewport(0, 0, w, h);

	// Set the clipping volume
	glOrtho(-100.0f, windowWidth, -100.0f, windowHeight, -200.0f, 200.0f);

	glLightfv(GL_LIGHT0,GL_POSITION, lightpos);

	glRotatef(30.0f, 1.0f, 0.0f, 0.0f);
	glRotatef(330.0f, 0.0f, 1.0f, 0.0f);
	}

int main(int argc, char* argv[])
	{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutCreateWindow("3D Effects Demo");
	glutReshapeFunc(ChangeSize);
	glutKeyboardFunc(KeyPressFunc);
	glutDisplayFunc(RenderScene);
	glGenTextures(4,textures);

	SetupRC();

	glutMainLoop();
	glDeleteTextures(4,textures);
	return 0;
	}