CODEWITHSUNDEEP
c++openglglutwavefrontopengl-compat
lambozsolty
lambozsolty

Reputation: 81

How to set the size of an opengl object?

I have to display an object in opengl(it's a homework) and I found a good code on the internet,but the size of the displayed object is very small,and I don't know how to change it to display the object in bigger size.

I think that I have to modify reshape, drawObject and display functions, but I don't know opengl and it's functions so I don't know that which part of the code should I modify.

#include<stdio.h>
#include"glut.h"

GLuint object;
float objectrot;
char ch = '1';

void loadObj(const char* fname)
{
    FILE* fp;
    int read;
    GLfloat x, y, z;
    char ch;

    object = glGenLists(1);
    fp = fopen(fname, "r");

    if (!fp)
    {
        printf("can't open file %s\n", fname);
        exit(1);
    }
    glPointSize(2.0);
    glNewList(object, GL_COMPILE);
    {
        glPushMatrix();
        glBegin(GL_POINTS);
        while (!(feof(fp)))
        {
            read = fscanf(fp, "%c %f %f %f", &ch, &x, &y, &z);
            if (read == 4 && ch == 'v')
            {
                glVertex3f(x, y, z);
            }
        }
        glEnd();
    }

    glPopMatrix();
    glEndList();

    fclose(fp);
}

void reshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(60, (GLfloat)w / (GLfloat)h, 0.1, 1000.0);
    glMatrixMode(GL_MODELVIEW);
}

void drawObject()
{
    glPushMatrix();
    glTranslatef(0, -40.00, -105);
    glColor3f(255, 255, 255);
    glScalef(0.1, 0.1, 0.1);
    glRotatef(objectrot, 0, 1, 0);
    glCallList(object);
    glPopMatrix();
    objectrot += 0.001;
    if (objectrot > 360)objectrot -= 360;
}

void display(void)
{
    glClearColor(0.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    drawObject();
    glutSwapBuffers(); 
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(800, 450);
    glutInitWindowPosition(20, 20);
    glutCreateWindow("ObjLoader");
    glutReshapeFunc(reshape);
    glutDisplayFunc(display);
    glutIdleFunc(display);
    loadObj("cat.obj");
    glutMainLoop();
    return 0;
}

I expect a larger object in the window,but it is very small

Upvotes: 2

Views: 2830

Answers (1)

Mode77
Mode77

Reputation: 1041

You need to increase the scale factor.

void drawObject()
{
    glPushMatrix();
    glTranslatef(0, -40.00, -105);
    glColor3f(255, 255, 255);
    glScalef(1.0, 1.0, 1.0);
    glRotatef(objectrot, 0, 1, 0);
    glCallList(object);
    glPopMatrix();
    objectrot += 0.001;
    if (objectrot > 360)objectrot -= 360;
}

You should pass in a larger number to glScalef(). Try 1.0 and see if that works.

Upvotes: 2

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