Using glArrayElement does not produce visible output - opengl

Question

Can somebody tell me what is mistake here. It shows display window, but unfortunately doesn't draw a triangle.
#include<glut.h>
GLint vertices[] ={ /*vertex array */
0.25, 0.25,
-0.9, 0.8,
0.5, -0.5
-0.2, -0.8
};
GLfloat colors[]={ /*color array*/
1.0, 0.0, 0.0,
0.0, 1.0, 0.0,
0.0, 0.0, 1.0,
1.0, 1.0, 0.0
};
void display(){
glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
glEnableClientState(GL_COLOR_ARRAY); /* enabling color array*/
glEnableClientState(GL_VERTEX_ARRAY); /*enableing vertex array */
glColorPointer(3, GL_FLOAT, 0, colors);
glVertexPointer(2, GL_FLOAT, 0, vertices);
glBegin(GL_TRIANGLES); /* dereferencing */
glArrayElement(0);
glArrayElement(1);
glArrayElement(2);
glEnd();
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glFlush();
}
void main() {
glutInitDisplayMode(GLUT_RGBA);
glutInitWindowPosition(200, 200);
glutInitWindowSize(300,300);
glutCreateWindow("My application");
glutDisplayFunc(display);
glutMainLoop();
}

Answer 1

Your vertices array is of type GLint[], so all the float (or rather double) values in the initialization expression will just be truncated to 0 and it won't match the type given in glVertexPointer either, causing whatever weird results (though in exactly this case the binary representations of all those integer 0s are probably also the binary representations of a float 0.0f). Given the use of GL_FLOAT in glVertexPointer you probably meant it to be GLfloat vertices[].
(Side note: As noted in the comments the glArrayElement function is pretty useless and if you're already using vertex arrays, then you should actually draw them with a single array draw call instead of a million glArrayElement calls inside a glBegin/glEnd block, which is the whole purpose and advantage of arrays compared to glBegin/glEnd. So in fact your glBegin/glEnd block can be replaced by a simple glDrawArrays(GL_TRIANGLES, 0, 3);. But with the above mentioned correction of the array type it should at least work correctly.)