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Imported from P4

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <malloc.h>
#include <fcntl.h>
#include <unistd.h>
#include <math.h>
#include <GL/glut.h>
#include <GL/rgb.h>


#define STEPCOUNT 40
#define FALSE 0
#define TRUE 1
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#define MIN(a, b) (((a) < (b)) ? (a) : (b))


enum {
    OP_NOOP = 0,
    OP_STRETCH,
    OP_DRAWPOINT,
    OP_DRAWIMAGE
};


typedef struct _cRec {
    float x, y;
} cRec;

typedef struct _vertexRec {
    float x, y;
    float dX, dY;
    float tX, tY;
} vertexRec;


GLenum doubleBuffer;
int imageSizeX, imageSizeY;
RGBImageRec *image = NULL;
cRec cList[50];
vertexRec vList[5];
int cCount, cIndex[2], cStep;
GLenum op = OP_NOOP;


void DrawImage(void)
{

    glRasterPos2i(0, 0);
    glDrawPixels(image->sizeX, image->sizeY, GL_RGB, GL_UNSIGNED_BYTE,
		 image->data);

    if (doubleBuffer) {
	glutSwapBuffers();
    } else {
	glFlush();
    }

    glRasterPos2i(0, 0);
    glDrawPixels(image->sizeX, image->sizeY, GL_RGB, GL_UNSIGNED_BYTE,
		 image->data);
}

void DrawPoint(void)
{
    int i;

    glColor3f(1.0, 0.0, 1.0);
    glPointSize(3.0);
    glBegin(GL_POINTS);
	for (i = 0; i < cCount; i++) {
	    glVertex2f(cList[i].x, cList[i].y);
	}
    glEnd();

    if (doubleBuffer) {
	glutSwapBuffers();
    } else {
	glFlush();
    }
}

void InitVList(void)
{

    vList[0].x = 0.0;
    vList[0].y = 0.0;
    vList[0].dX = 0.0;
    vList[0].dY = 0.0;
    vList[0].tX = 0.0;
    vList[0].tY = 0.0;

    vList[1].x = (float)imageSizeX;
    vList[1].y = 0.0;
    vList[1].dX = 0.0;
    vList[1].dY = 0.0;
    vList[1].tX = 1.0;
    vList[1].tY = 0.0;

    vList[2].x = (float)imageSizeX;
    vList[2].y = (float)imageSizeY;
    vList[2].dX = 0.0;
    vList[2].dY = 0.0;
    vList[2].tX = 1.0;
    vList[2].tY = 1.0;

    vList[3].x = 0.0;
    vList[3].y = (float)imageSizeY;
    vList[3].dX = 0.0;
    vList[3].dY = 0.0;
    vList[3].tX = 0.0;
    vList[3].tY = 1.0;

    vList[4].x = cList[0].x;
    vList[4].y = cList[0].y;
    vList[4].dX = (cList[1].x - cList[0].x) / STEPCOUNT;
    vList[4].dY = (cList[1].y - cList[0].y) / STEPCOUNT;
    vList[4].tX = cList[0].x / (float)imageSizeX;
    vList[4].tY = cList[0].y / (float)imageSizeY;
}

void ScaleImage(int sizeX, int sizeY)
{
    GLubyte *buf;

    buf = (GLubyte *)malloc(3*sizeX*sizeY);
    gluScaleImage(GL_RGB, image->sizeX, image->sizeY, GL_UNSIGNED_BYTE,
                  image->data, sizeX, sizeY, GL_UNSIGNED_BYTE, buf);
    free(image->data);
    image->data = buf;
    image->sizeX = sizeX;
    image->sizeY = sizeY;
}

void SetPoint(int x, int y)
{

    cList[cCount].x = (float)x;
    cList[cCount].y = (float)y;
    cCount++;
}

void Stretch(void)
{

    glBegin(GL_TRIANGLES);
	glTexCoord2f(vList[0].tX, vList[0].tY);
	glVertex2f(vList[0].x, vList[0].y);
	glTexCoord2f(vList[1].tX, vList[1].tY);
	glVertex2f(vList[1].x, vList[1].y);
	glTexCoord2f(vList[4].tX, vList[4].tY);
	glVertex2f(vList[4].x, vList[4].y);
    glEnd();

    glBegin(GL_TRIANGLES);
	glTexCoord2f(vList[1].tX, vList[1].tY);
	glVertex2f(vList[1].x, vList[1].y);
	glTexCoord2f(vList[2].tX, vList[2].tY);
	glVertex2f(vList[2].x, vList[2].y);
	glTexCoord2f(vList[4].tX, vList[4].tY);
	glVertex2f(vList[4].x, vList[4].y);
    glEnd();

    glBegin(GL_TRIANGLES);
	glTexCoord2f(vList[2].tX, vList[2].tY);
	glVertex2f(vList[2].x, vList[2].y);
	glTexCoord2f(vList[3].tX, vList[3].tY);
	glVertex2f(vList[3].x, vList[3].y);
	glTexCoord2f(vList[4].tX, vList[4].tY);
	glVertex2f(vList[4].x, vList[4].y);
    glEnd();

    glBegin(GL_TRIANGLES);
	glTexCoord2f(vList[3].tX, vList[3].tY);
	glVertex2f(vList[3].x, vList[3].y);
	glTexCoord2f(vList[0].tX, vList[0].tY);
	glVertex2f(vList[0].x, vList[0].y);
	glTexCoord2f(vList[4].tX, vList[4].tY);
	glVertex2f(vList[4].x, vList[4].y);
    glEnd();

    if (doubleBuffer) {
	glutSwapBuffers();
    } else {
	glFlush();
    }

    if (++cStep < STEPCOUNT) {
	vList[4].x += vList[4].dX;
	vList[4].y += vList[4].dY;
    } else {
	cIndex[0] = cIndex[1];
	cIndex[1] = cIndex[1] + 1;
	if (cIndex[1] == cCount) {
	    cIndex[1] = 0;
	}
	vList[4].dX = (cList[cIndex[1]].x - cList[cIndex[0]].x) / STEPCOUNT;
	vList[4].dY = (cList[cIndex[1]].y - cList[cIndex[0]].y) / STEPCOUNT;
	cStep = 0;
    }
}

void Key(unsigned char key, int x, int y)
{

    switch (key) {
      case ' ':
	if (cCount > 1) {
	    InitVList();
	    cIndex[0] = 0;
	    cIndex[1] = 1;
	    cStep = 0;
	    glEnable(GL_TEXTURE_2D);
	    op = OP_STRETCH;
	}
	glutPostRedisplay();
	break;
      case 27:
	free(image->data);
        exit(0);
    }
}

void Mouse(int button, int state, int mouseX, int mouseY)
{

    if (state == GLUT_DOWN) {
	if (op == OP_STRETCH) {
	    glDisable(GL_TEXTURE_2D);
	    cCount = 0;
	    op = OP_DRAWIMAGE;
	} else {
	    SetPoint(mouseX, imageSizeY-mouseY);
	    op = OP_DRAWPOINT;
	}
	glutPostRedisplay();
    }
}

void Animate(void)
{

    switch (op) {
      case OP_STRETCH:
	Stretch();
	break;
      case OP_DRAWPOINT:
	DrawPoint();
	break;
      case OP_DRAWIMAGE:
	DrawImage();
	break;
    }
}

static void Args(int argc, char **argv)
{
    GLint i;

    doubleBuffer = GL_FALSE;

    for (i = 1; i < argc; i++) {
	if (strcmp(argv[i], "-sb") == 0) {
	    doubleBuffer = GL_FALSE;
	} else if (strcmp(argv[i], "-db") == 0) {
	    doubleBuffer = GL_TRUE;
	} else if (strcmp(argv[i], "-f") == 0) {
	    if (i+1 >= argc || argv[i+1][0] == '-') {
		printf("-f (No file name).\n");
		exit(1);
	    } else {
		image = rgbImageLoad(argv[++i]);
		if (image == NULL) {
		    printf("-f (Bad file name).\n");
		    exit(1);
		}
	    }
	}
    }
}

int main(int argc, char **argv)
{
    GLenum type;

    glutInit(&argc, argv);
    Args(argc, argv);

    if (image == NULL) {
	printf("No texture file.\n");
	exit(1);
    }

    imageSizeX = (int)powf(2.0, (float)((int)(logf(image->sizeX)/logf(2.0))));
    imageSizeY = (int)powf(2.0, (float)((int)(logf(image->sizeY)/logf(2.0))));


    type = GLUT_RGB;
    type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
    glutInitDisplayMode(type);
    glutInitWindowSize(imageSizeX, imageSizeY);
    glutCreateWindow("Stretch");

    glViewport(0, 0, imageSizeX, imageSizeY);
    gluOrtho2D(0, imageSizeX, 0, imageSizeY);
    glClearColor(0.0, 0.0, 0.0, 0.0);

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glPixelStorei(GL_PACK_ALIGNMENT, 1);

    ScaleImage(imageSizeX, imageSizeY);

    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D, 0, 3, image->sizeX, image->sizeY, 0,
                 GL_RGB, GL_UNSIGNED_BYTE, (unsigned char *)image->data);

    cCount = 0;
    cIndex[0] = 0;
    cIndex[1] = 0;
    cStep = 0;
    op = OP_DRAWIMAGE;

    glutKeyboardFunc(Key);
    glutMouseFunc(Mouse);
    glutIdleFunc(Animate);
    glutDisplayFunc(Animate);
    glutMainLoop();
}