View Full Version : OpenGL colour not able to render colour

05-12-2010, 12:19 AM
I am trying to use openGL over tinyX.
My platform is arm v7. I have successfully compiled both tinyX and openGL for arm-v7.

Now I am trying to run some simple opengl applications over the ported tinyX.

The example that I am using right now is taken from nehe.org.
The example creates a simple glwindow using glut apis.
After that it creates a "Triagle" and "Rectangle" in that window.

When I run the same example on my x-86 based linux, I am able to see the proper output with colours of the background being black and the colours in the geometrical figures being as programmed.

But when I run the same example on my arm-v7 based linux, I get the geometry of the figure being properly drawn but without any colours.

// This code was created by Jeff Molofee '99 (ported to Linux/GLUT by Richard Campbell '99)
// If you've found this code useful, please let me know.
// Visit me at www.demonews.com/hosted/nehe (http://www.demonews.com/hosted/nehe)
// (email Richard Campbell at ulmont@bellsouth.net)
#include <GL/glut.h> // Header File For The GLUT Library
#include <GL/gl.h> // Header File For The OpenGL32 Library
#include <GL/glu.h> // Header File For The GLu32 Library
#include <unistd.h> // Header File for sleeping.

/* ASCII code for the escape key. */
#define ESCAPE 27

/* The number of our GLUT window */
int window;

/* A general OpenGL initialization function. Sets all of the initial parameters. */
void InitGL(int Width, int Height) // We call this right after our OpenGL window is created.
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // This Will Clear The Background Color To Black
glClearDepth(1.0); // Enables Clearing Of The Depth Buffer
glDepthFunc(GL_LESS); // The Type Of Depth Test To Do
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glShadeModel(GL_SMOOTH); // Enables Smooth Color Shading

glLoadIdentity(); // Reset The Projection Matrix

gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f); // Calculate The Aspect Ratio Of The Window


/* The function called when our window is resized (which shouldn't happen, because we're fullscreen) */
void ReSizeGLScene(int Width, int Height)
if (Height==0) // Prevent A Divide By Zero If The Window Is Too Small

glViewport(0, 0, Width, Height); // Reset The Current Viewport And Perspective Transformation



/* The main drawing function. */
void DrawGLScene()
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
glLoadIdentity(); // Reset The View

glTranslatef(-1.5f,0.0f,-6.0f); // Move Left 1.5 Units And Into The Screen 6.0

// draw a triangle (in smooth coloring mode)
glBegin(GL_POLYGON); // start drawing a polygon
glColor4f(1.0f,0.0f,0.0f,1.0f); // Set The Color To Red
glVertex3f( 0.0f, 1.0f, 0.0f); // Top
glColor4f(0.0f,1.0f,0.0f,1.0f); // Set The Color To Green
glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right
glColor4f(0.0f,0.0f,1.0f,1.0f); // Set The Color To Blue
glVertex3f(-1.0f,-1.0f, 0.0f); // Bottom Left
glEnd(); // we're done with the polygon (smooth color interpolation)

glTranslatef(3.0f,0.0f,0.0f); // Move Right 3 Units

// draw a square (quadrilateral)
glColor4f(0.5f,0.5f,1.0f,1.0f); // set color to a blue shade.
glBegin(GL_QUADS); // start drawing a polygon (4 sided)
glVertex3f(-1.0f, 1.0f, 0.0f); // Top Left
glVertex3f( 1.0f, 1.0f, 0.0f); // Top Right
glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right
glVertex3f(-1.0f,-1.0f, 0.0f); // Bottom Left
glEnd(); // done with the polygon

// we need to swap the buffer to display our drawing.

/* The function called whenever a key is pressed. */
void keyPressed(unsigned char key, int x, int y)
/* sleep to avoid thrashing this procedure */

/* If escape is pressed, kill everything. */
if (key == ESCAPE)
/* shut down our window */

/* exit the program...normal termination. */

int main(int argc, char **argv)
/* Initialize GLUT state - glut will take any command line arguments that pertain to it or
X Windows - look at its documentation at http://reality.sgi.com/mjk/spec3/spec3.html */
glutInit(&amp;argc, argv);

/* Select type of Display mode:
Double buffer
RGBA color
Alpha components supported
Depth buffer */

/* get a 640 x 480 window */
glutInitWindowSize(640, 480);

/* the window starts at the upper left corner of the screen */
glutInitWindowPosition(0, 0);

/* Open a window */
window = glutCreateWindow("Jeff Molofee's GL Code Tutorial ... NeHe '99");

/* Register the function to do all our OpenGL drawing. */

/* Go fullscreen. This is as soon as possible. */

/* Even if there are no events, redraw our gl scene. */

/* Register the function called when our window is resized. */

/* Register the function called when the keyboard is pressed. */

/* Initialize our window. */
InitGL(640, 480);

/* Start Event Processing Engine */

return 1;

05-12-2010, 02:37 AM
successfully compiled ... openGL for arm-v7
What GL source did you use ?
It is quite likely this is a bug of the GL source implementation you use.

05-12-2010, 03:01 AM
i am using mesa implemention for OpenGL

05-16-2010, 03:15 AM
o_O Unfortunately.....