/*
 * Copyright (c) 1996-1999  Silicon Graphics, Inc.  All rights reserved.
 *
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
 *
 * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
 * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF THE
 * POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* transforms.c - draw a triangle under the effect of a rotation, 
 *		a translation and a scale
 *
 *	Escape key	- exit program
 */

#include <GL/glut.h>	/* includes gl.h, glu.h */
#include <stdio.h>

#include "axes.h"

/*  Function Prototypes  */

GLvoid  initgfx( GLvoid );
GLvoid  keyboard( GLubyte, GLint, GLint );
GLvoid  drawScene( GLvoid );

void drawTriangle( GLfloat red, GLfloat green, GLfloat blue );

void printHelp( char * );

/* Global Definitions */

#define KEY_ESC	27	/* ascii value for the escape key */

void
main( int argc, char *argv[] )
{
	GLsizei width, height;

	glutInit( &argc, argv );

	width = glutGet( GLUT_SCREEN_WIDTH ); 
	height = glutGet( GLUT_SCREEN_HEIGHT );
	glutInitWindowPosition( 0, height / 4 );
	glutInitWindowSize( width / 2, height / 2 );
	glutInitDisplayMode( GLUT_RGBA );
	glutCreateWindow( argv[0] );

	initgfx();

	glutKeyboardFunc( keyboard );
	glutDisplayFunc( drawScene ); 

	printHelp( argv[0] );

	glOrtho( -2.0, 2.0, -2.0, 2.0, -1.0, 1.0 );

	glutMainLoop();
}

void
printHelp( char *progname )
{
	fprintf(stdout, "\n%s - demonstrates modeling transformations\n\n"
		"Escape Key		- exit the program\n\n",
		progname);
}

GLvoid
initgfx( GLvoid )
{
	glClearColor( 0.0, 0.0, 1.0, 1.0 );
	glShadeModel( GL_FLAT );
}

GLvoid 
keyboard( GLubyte key, GLint x, GLint y )
{
	switch (key) {
	case KEY_ESC:	/* Exit whenever the Escape key is pressed */
		exit(0);
	}
}

GLvoid
drawTriangle( GLfloat red, GLfloat green, GLfloat blue )
{
	glColor3f( red, green, blue );
	glBegin( GL_TRIANGLES );
		glVertex2f( -0.5f, -0.5f );
		glVertex2f( 0.5f, -0.5f );
		glVertex2f( 0.0f, 0.5f );
	glEnd();
}

GLvoid
drawScene( GLvoid )
{
	glClear( GL_COLOR_BUFFER_BIT );

	/* draw a black triangle centered at the origin */
		drawTriangle( 0.0f, 0.0f, 0.0f );

	/* Draw x and y axes to show the origin */
	XYaxes();

		/* move over a bit and draw another triangle */
		glTranslatef( 0.5f, 0.0f, 0.0f );
		drawTriangle( 0.3f, 0.3f, 0.3f ); 

	/* move over a bit and draw a rotated triangle */
		glTranslatef( 0.5f, 0.0f, 0.0f );

		/* Rotate 15 degrees counter-clockwise around the positive Z axis */
		glRotatef( -15.0f, 0.0f, 0.0f, 1.0f );
		drawTriangle( 0.7f, 0.7f, 0.7f );

	/* move over a bit and draw a scaled triangle */
		glTranslatef( 0.5f, 0.0f, 0.0f );

		/* Scale the triangle by one-half in all dimensions */
		glScalef( -0.5f, 0.5f, 0.5f );
		drawTriangle( 1.0f, 1.0f, 1.0f ); 	/* draw green triangle */
	XYaxes();

	glFlush();
}