OpenGL ES Texture Problems

Nibbie

Posts: 2
Joined: 2009.02

Post: #1

Feb 8, 2009 — 04:21 PM

Ok I'm new to OpenGL and I'm working on the iPhone trying to add textures to a cube I've been trying for a week to get the cube textured but can't can someone help me out here is the code I'm using:

Code:

- (void)drawView:(GLView*)view;

{

    static GLfloat        rquad;           

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glLoadIdentity();

    glEnable(GL_TEXTURE_2D);

    glEnableClientState(GL_VERTEX_ARRAY);

    glTranslatef(0.0f,0.0f,-15.0f);

    glRotatef(rquad, 0.0f, 1.0f, 0.0f);    

    glVertexPointer(3, GL_FLOAT, 0, box1_vertices);

    glTexCoordPointer(2, GL_FLOAT, 0, box1_Texture);

    glEnableClientState(GL_TEXTURE_COORD_ARRAY);

        for(int i = 0; i < num_box1_indices; i += 3)

    { 

        glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, &box1_indices[i]);

    }

    glDisableClientState(GL_VERTEX_ARRAY);

    glDisableClientState(GL_TEXTURE_COORD_ARRAY);

    glDisable(GL_TEXTURE_2D);

    static NSTimeInterval lastDrawTime;

    if (lastDrawTime)

    {

        NSTimeInterval timeSinceLastDraw = [NSDate timeIntervalSinceReferenceDate] - lastDrawTime;

        rquad-=70 * timeSinceLastDraw;    

    }

    lastDrawTime = [NSDate timeIntervalSinceReferenceDate];

}

-(void)setupView:(GLView*)view

{    CGImageRef spriteImage;    

     size_t    width, height;

    CGContextRef spriteContext;

    GLubyte *spriteData;

    GLuint spriteTexture;    

    const GLfloat zNear = 0.1, 

    zFar = 100.0, 

    fieldOfView = 60.0; 

    GLfloat size; 

    glMatrixMode(GL_PROJECTION); 

    glEnable(GL_DEPTH_TEST); 

    size = zNear * tanf(DEGREES_TO_RADIANS(fieldOfView) / 2.0); 

    CGRect rect = view.bounds; 

    glFrustumf(-size, size, -size / (rect.size.width / rect.size.height), size / 

               (rect.size.width / rect.size.height), zNear, zFar); 

    glViewport(0, 0, rect.size.width, rect.size.height); 

    glMatrixMode(GL_MODELVIEW); 

    spriteImage = [UIImage imageNamed:@"box.bmp"].CGImage;

    width = CGImageGetWidth(spriteImage);

    height = CGImageGetHeight(spriteImage);

    if(spriteImage) {

        spriteData = (GLubyte *) malloc(width * height * 4);

        spriteContext = CGBitmapContextCreate(spriteData, width, height, 8, width * 4, CGImageGetColorSpace(spriteImage), kCGImageAlphaPremultipliedLast);

.

        CGContextDrawImage(spriteContext, CGRectMake(0.0, 0.0, (CGFloat)width, (CGFloat)height), spriteImage);

        CGContextRelease(spriteContext);

        glGenTextures(1, &spriteTexture);

        glBindTexture(GL_TEXTURE_2D, spriteTexture);

        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData);

        free(spriteData);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        glEnable(GL_TEXTURE_2D);

        glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

        glEnable(GL_BLEND);

    }

    //glLoadIdentity(); 

    glClearColor(0.0f, 0.0f, 1.0f, 1.0f); 

}

##########################################
Thats the draw code this is what's being drawn I've put it in a .h file.

Code:

#define box1_H 

const int num_box1_indices  = 36;

const int num_box1_vertices  = 8;

float box1_vertices  [] = {

     -3.2126,0.0000,1.1594,

     -3.2126,0.0000,-0.4348,

     -1.8116,0.0000,-0.4348,

     -1.8116,0.0000,1.1594,

     -3.2126,1.6425,1.1594,

     -1.8116,1.6425,1.1594,

     -1.8116,1.6425,-0.4348,

     -3.2126,1.6425,-0.4348,

 };

float box1_Texture[] = {

    1.0000,0.0000,

    1.0000,1.0000,

    0.0000,1.0000,

    0.0000,0.0000,

 };

short box1_indices [] = {

    0,1,2,

    2,3,0,

    4,5,6,

    6,7,4,

    0,3,5,

    5,4,0,

    3,2,6,

    6,5,3,

    2,1,7,

    7,6,2,

    1,0,4,

    4,7,1,

 };

################################
Now this draws a cube and textures two sides that it can't get the whole cube textured any help is appreciated.

Kezhaya

Nibbie

Posts: 1
Joined: 2010.07

Post: #2

Jul 12, 2010 — 05:57 AM

I'm a noob at OpenGL too, and maybe this answer makes no sense anymore.

Even so, I think you don't need that for cycle to use glDrawElements.
At least I only make one call and pass the array as the last argument, and it works.

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