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POOpenGL - creating a plane surface with a cone-like spotlight
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  1. POOpenGL - creating a plane surface with a cone-like spotlight
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    copied!<p>I'm having troubles with creating a rectangular surface that has a cone-like spotlight pointing on it. So far, I've tried to create a 2D cube surface (<code>glutSolidCube()</code>) and use <code>GL_SPOT_XXX</code> to create the spotlight. But I don't for what reason, the light just keeps scattering all over the surface instead of gather into a spot.</p> <p>So here is my code so far, you can just focus on the <code>init_light()</code> and <code>display()</code> functions. The other functions are there for you to reference if you need to :)</p> <pre><code>void rotateCamera() { /* Rotate camera 2 degrees about selected axis */ theta[axis] += dtheta; if (theta[axis] &gt; 360.0 ) theta[axis] -= 360.0; glutPostRedisplay(); } void computeCameraPosition() { GLdouble M[16]; glMatrixMode(GL_MODELVIEW); glPushMatrix(); glLoadIdentity(); glTranslatef(centroid[0], centroid[1], centroid[2]); glRotatef(theta[0], 1.0, 0.0, 0.0); glRotatef(theta[1], 0.0, 1.0, 0.0); glRotatef(theta[2], 0.0, 0.0, 1.0); glTranslatef(-centroid[0], -centroid[1], -centroid[2]); glGetDoublev(GL_MODELVIEW_MATRIX, M); GLdouble newvec[16]; glMultMatrixd(init_vec); glGetDoublev(GL_MODELVIEW_MATRIX, newvec); glPopMatrix(); /* the 1st and 2nd columns are the eye position and new y-axis direction */ memcpy(eye, newvec, sizeof(GLdouble)*4); memcpy(yaxis, newvec+4, sizeof(GLdouble)*4); } void init_light() { GLfloat spot_direction[] = { 1.0, 1.0, 0.0 }; glLightfv( GL_LIGHT0, GL_SPOT_DIRECTION, spot_direction ); glLightf( GL_LIGHT0, GL_SPOT_EXPONENT, 2.0 ); glLightf( GL_LIGHT0, GL_SPOT_CUTOFF, 45.0 ); glShadeModel(GL_SMOOTH); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_COLOR_MATERIAL); } void display() { computeCameraPosition(); glClearColor(0.9, 0.9, 0.9, 1.0); glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); gluLookAt(eye[0], eye[1], eye[2], centroid[0], centroid[1], centroid[2], yaxis[0], yaxis[1], yaxis[2]); glutSolidCube(2.0); glFlush(); glutSwapBuffers(); } int main(int argc, char **argv) { glutInit(&amp;argc, argv); glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(800, 800); glutInitWindowPosition (200, 100); glutCreateWindow("Scene Editor"); init_light(); glutDisplayFunc(display); glutMainLoop(); } </code></pre>
 

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