Re: [Vala] How to bitwise math and implement a jagged array in Vala?

[Thomas F Steinhauer <tom_steinhauer hotmail com>]

Dear Evan,
I tried the code that you have listed, It worked but no texture showed 
up on the quads. They were empty.

I have pasted the whole code here as I have it now in hopes that someone 
might be able to figure out what is going on or maybe if I did something 
wrong.

> /*
>  * Texture: CheckerBoard-pattern texture
>  */
>
> const int checkImageWidth = 64;      // Texture image rows and columns
> const int checkImageHeight = 64;
> GLubyte [,,] checkImage; // Texture image data
> GLuint texName;
>
> private static uint8[,,] makeCheckImage (int width = 64, int height = 
> 64) {
>   uint8[,,] check_image = new uint8[height,width,4];
>
>   for ( var i = 0 ; i < height ; i++ ) {
>     for ( var j = 0 ; j < width ; j++ ) {
>       uint8 c = (((uint8)((i&0x8)==0))^((uint8)((j&0x8)==0)))*255;
>       check_image[i,j,0] = c;
>       check_image[i,j,1] = c;
>       check_image[i,j,2] = c;
>       check_image[i,j,3] = 255;
>     }
>   }
>
>   return check_image;
> }
>
> void init()
> {
>    glClearColor (0.0f, 0.0f, 0.0f, 0.0f);
>    glShadeModel(GL_FLAT);
>    glEnable(GL_DEPTH_TEST);
>
>    makeCheckImage();
>    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
>
>    glGenTextures(1, (GLuint[])texName);
>    glBindTexture(GL_TEXTURE_2D, texName);
>
>    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
>    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
>    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
>    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
>    glTexImage2D(GL_TEXTURE_2D, 0, (GLint)GL_RGBA, checkImageWidth, 
> checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);
> }
>
> void display()
> {
>    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
>    glEnable(GL_TEXTURE_2D);
>    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
>    glBindTexture(GL_TEXTURE_2D, texName);
>    glBegin(GL_QUADS);
>    glTexCoord2f(0.0f, 0.0f); glVertex3f(-2.0f, -1.0f, 0.0f);
>    glTexCoord2f(0.0f, 1.0f); glVertex3f(-2.0f, 1.0f, 0.0f);
>    glTexCoord2f(1.0f, 1.0f); glVertex3f(0.0f, 1.0f, 0.0f);
>    glTexCoord2f(1.0f, 0.0f); glVertex3f(0.0f, -1.0f, 0.0f);
>
>    glTexCoord2f(0.0f, 0.0f); glVertex3f(1.0f, -1.0f, 0.0f);
>    glTexCoord2f(0.0f, 1.0f); glVertex3f(1.0f, 1.0f, 0.0f);
>    glTexCoord2f(1.0f, 1.0f); glVertex3f(2.41421f, 1.0f, -1.41421f);
>    glTexCoord2f(1.0f, 0.0f); glVertex3f(2.41421f, -1.0f, -1.41421f);
>    glEnd();
>    glFlush();
>    glDisable(GL_TEXTURE_2D);
> }
>
> void reshape(int w, int h)
> {
>    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
>    glMatrixMode(GL_PROJECTION);
>    glLoadIdentity();
>    gluPerspective(60.0, (GLfloat) w/(GLfloat) h, 1.0, 30.0);
>    glMatrixMode(GL_MODELVIEW);
>    glLoadIdentity();
>    glTranslatef(0.0f, 0.0f, -3.6f);
> }
>
> void keyboard (uchar key, int x, int y)
> {
>    switch (key) {
>       case 27:
>          //exit(0);
>          break;
>       default:
>          break;
>    }
> }
>
> void main(string[] args)
> {
>    glutInit(ref args.length, args);
>    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA | GLUT_DEPTH);
>    glutInitWindowSize(250, 250);
>    glutInitWindowPosition(100, 100);
>    glutCreateWindow("checker");
>    init();
>    glutDisplayFunc(display);
>    glutReshapeFunc(reshape);
>    glutKeyboardFunc(keyboard);
>    glutMainLoop();
> }
Thanks
Tom

On 07/02/2013 07:02 PM, Evan Nemerson wrote:
> On Tue, 2013-07-02 at 18:49 -0500, Thomas F Steinhauer wrote:
> > I tried your code as you suggested however that did not work. I guess
> > the real question that I am asking here is has anyone successfully
> > generated a Checker board type texture with OpenGL and Vala and
> > displayed it on a cube or square. That is the code that I really need.
> > It seems that because Vala does not supported "jagged" arrays that this
> > is not possible or did I miss something in the reading somewhere?
> Yes.  For one thing, there is no reason this needs to be a jagged array.
> The C example isn't.  The part of the tutorial I linked to explains the
> difference.
>
> Here is everything together.  I've changed GL.ubyte to uint8 because it
> was more convenient (I don't get an opengl vapi), but s/uint8/GL.ubyte/
> and it should be exactly what you're after.
>
>
> private static uint8[,,]
> make_check_image (int width = 64, int height = 64) {
>    uint8[,,] check_image = new uint8[height,width,4];
>
>    for ( var i = 0 ; i < height ; i++ ) {
>      for ( var j = 0 ; j < width ; j++ ) {
>        uint8 c = (((uint8)((i&0x8)==0))^((uint8)((j&0x8)==0)))*255;
>        check_image[i,j,0] = c;
>        check_image[i,j,1] = c;
>        check_image[i,j,2] = c;
>        check_image[i,j,3] = 255;
>      }
>    }
>
>    return check_image;
> }
>
>
> -Evan