0730 code

basic_transform.cpp

#include <GL/glut.h>
#include <cstdio>
#include <cmath>

GLfloat rot = 0.0;
GLfloat PI = (GLfloat)3.14159265;
GLfloat seed_2 = 0.0;

enum EXAMPLE{ NORMAL, ROTATE, TRANSLATE, SCALE };
EXAMPLE mode = SCALE;

void init(void)
{
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glShadeModel(GL_FLAT);
}

void display(void)
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(1.0, 1.0, 1.0);

	glLoadIdentity();
	/* viewing transformation  */
	gluLookAt(0.0, 0.0, 3.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

	/* modeling transformation */
	switch (mode)
	{
	case ROTATE:
		glRotatef(rot, 0.0, 0.0, 1.0);
		break;
	case TRANSLATE:
		glTranslatef((GLfloat)cos((float)seed_2 * PI), (GLfloat)sin((float)seed_2 * PI), 0.0);
		break;
	case SCALE:
		glScalef((GLfloat)abs(cos((float)seed_2 * PI * 0.5) + 0.0001), (GLfloat)abs(sin((float)seed_2 * PI * 0.5) + 0.0001), 1.0);
		break;
	default:
		break;
	}
	glutWireCube(1.0);
	glFlush();
}

void reshape(int w, int h)
{
	glViewport(0, 0, (GLsizei)w, (GLsizei)h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glFrustum(-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);
	glMatrixMode(GL_MODELVIEW);
}

void timer(int p)
{
	switch (mode)
	{
	case ROTATE:
		(rot >= 360.0) ? (rot -= 359.0) : (rot += 1.0);
		break;
	case TRANSLATE:
	case SCALE:
		(seed_2 >= 2.0) ? (seed_2 -= (GLfloat)1.95) : (seed_2 += (GLfloat)0.05);
		break;
	default:
		break;
	}
	glutPostRedisplay();
	glutTimerFunc(50, timer, 1);
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(100, 100);
	glutCreateWindow(argv[0]);

	init();

	glutDisplayFunc(display);
	glutTimerFunc(50, timer, 1);
	glutReshapeFunc(reshape);

	glutMainLoop();
	return 0;
}

pushpop.cpp

#include <GL/glut.h>
#include <cstdio>
#include <cmath>

GLfloat rot = 0.0;
GLfloat PI = (GLfloat)3.14159265;
GLfloat seed_2 = 0.0;

void drawcubeRGB(GLfloat r = 1.0, GLfloat g = 1.0, GLfloat b = 1.0)
{
	glPushMatrix();
		glRotatef(rot, 0.0, 1.0, 0.0);
		glRotatef(10, 1.0, 1.0, 0.0);
		glColor3f(r, g, b);
		glutWireCube(1.0);
	glPopMatrix();
}

void init(void)
{
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glShadeModel(GL_FLAT);
}

void display(void)
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(1.0, 1.0, 1.0);

	glLoadIdentity();
	gluLookAt(0.0, 0.0, 7.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

	glPushMatrix();
		drawcubeRGB(1.0, 1.0, 1.0);
	glPopMatrix();
	
	glPushMatrix();
		glTranslatef(2.0, 0.0, 0.0);
		drawcubeRGB(1.0, 0.0, 0.0);
	glPopMatrix();

	
	glPushMatrix();
		glTranslatef(0.0, 2.0, 0.0);
		drawcubeRGB(0.0, 1.0, 0.0);
			glPushMatrix();
			glTranslatef(2.0, 2.0, 0.0);
			drawcubeRGB(0.0, 0.0, 1.0);
			glPopMatrix();
	glPopMatrix();

	glFlush();
}

void reshape(int w, int h)
{
	glViewport(0, 0, (GLsizei)w, (GLsizei)h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glFrustum(-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);
	glMatrixMode(GL_MODELVIEW);
}

void timer(int p)
{
	rot += (GLfloat)1.0;
	glutPostRedisplay();
	glutTimerFunc(50, timer, 1);
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(100, 100);
	glutCreateWindow(argv[0]);

	init();

	glutDisplayFunc(display);
	glutTimerFunc(50, timer, 1);
	glutReshapeFunc(reshape);

	glutMainLoop();
	return 0;
}

shear.cpp

#include <GL/glut.h>

#include <cstdio>
GLfloat delta = 0.0;

void glShearXbyYf(GLfloat delta) {
	GLfloat m[] = {
		1.0, 0.0, 0.0, 0.0,
		delta, 1.0, 0.0, 0.0,
		0.0, 0.0, 1.0, 0.0,
		0.0, 0.0, 0.0, 1.0 };
	
	/* !important
		glMultMatrix is column-major

			m[0] m[4]  m[8] m[12]   v[0]
	M(v) =  m[1] m[5]  m[9] m[13] × v[1]
			m[2] m[6] m[10] m[14]   v[2]
			m[3] m[7] m[11] m[15]   v[3]
	*/

	glMultMatrixf(m);
}


void init(void)
{
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glShadeModel(GL_SMOOTH);
}

void display(void)
{
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(1.0, 1.0, 1.0);

	glLoadIdentity();
	/* viewing transformation  */
	gluLookAt(0.0, 0.0, 10.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

	/* modeling transformation */
	glShearXbyYf(delta);
	glRotatef(-90, 1.0, 0.0, 0.0);
	glutWireCone(2.0, 6.0, 10, 10);
	glutSwapBuffers();
}

void timer(int p)
{
	delta += (GLfloat)0.02;
	glutPostRedisplay();
	glutTimerFunc(50, timer, 1);
}

void reshape(int w, int h)
{
	glViewport(0, 0, (GLsizei)w, (GLsizei)h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glFrustum(-1.0, 1.0, -1.0, 1.0, 1, 20.0);
	glMatrixMode(GL_MODELVIEW);
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(100, 100);
	glutCreateWindow(argv[0]);

	init();

	glutDisplayFunc(display);
	glutTimerFunc(50, timer, 1);
	glutReshapeFunc(reshape);

	glutMainLoop();
	return 0;
}