将带纹理的3D模型从.obj文件导入到iOS OpenGl ES 2.0

Question

Im am currently trying to convert 3D models in .obj format with texture to Objective c compatible code and render them with OpenGL ES 2.0.

I am using [obj2opengl][1] from Heiko Behrens to convert the 3d model to a header file

The 3d model has UV Mapping with this texture image.

Everything is almost working, but somehow the textures are not rendered correctly and my cube shows up like this .

I have tried all sorts of things but cannot figure out what i am doing wrong or i just don't get it.

Here is my code on how i render the cube:

unsigned int boxNumVerts = 36;

float boxVerts [] = {
  // f 1/1/1 2/2/1 3/3/1 4/4/1 
  -0.5, -0.5, 0.5,
  -0.5, -0.5, -0.5,
  0.5, -0.5, -0.5,
  // f 1/1/1 2/2/1 3/3/1 4/4/1 
  -0.5, -0.5, 0.5,
  0.5, -0.5, 0.5,
  0.5, -0.5, -0.5,
  // f 5/5/2 6/6/2 7/7/2 8/8/2 
  -0.5, 0.5, 0.5,
  0.5, 0.5, 0.5,
  0.5, 0.5, -0.5,
  // f 5/5/2 6/6/2 7/7/2 8/8/2 
  -0.5, 0.5, 0.5,
  -0.5, 0.5, -0.5,
  0.5, 0.5, -0.5,
  // f 1/9/3 4/10/3 6/6/3 5/5/3 
  -0.5, -0.5, 0.5,
  0.5, -0.5, 0.5,
  0.5, 0.5, 0.5,
  // f 1/9/3 4/10/3 6/6/3 5/5/3 
  -0.5, -0.5, 0.5,
  -0.5, 0.5, 0.5,
  0.5, 0.5, 0.5,
  // f 4/11/4 3/12/4 7/7/4 6/6/4 
  0.5, -0.5, 0.5,
  0.5, -0.5, -0.5,
  0.5, 0.5, -0.5,
  // f 4/11/4 3/12/4 7/7/4 6/6/4 
  0.5, -0.5, 0.5,
  0.5, 0.5, 0.5,
  0.5, 0.5, -0.5,
  // f 3/13/5 2/14/5 8/8/5 7/7/5 
  0.5, -0.5, -0.5,
  -0.5, -0.5, -0.5,
  -0.5, 0.5, -0.5,
  // f 3/13/5 2/14/5 8/8/5 7/7/5 
  0.5, -0.5, -0.5,
  0.5, 0.5, -0.5,
  -0.5, 0.5, -0.5,
  // f 2/2/6 1/1/6 5/5/6 8/8/6 
  -0.5, -0.5, -0.5,
  -0.5, -0.5, 0.5,
  -0.5, 0.5, 0.5,
  // f 2/2/6 1/1/6 5/5/6 8/8/6 
  -0.5, -0.5, -0.5,
  -0.5, 0.5, -0.5,
  -0.5, 0.5, 0.5,
};


float boxTexCoords [] = {
  // f 1/1/1 2/2/1 3/3/1 4/4/1 
  0.5016, 0.7508,
  0.2504, 0.7508,
  0.2504, 1.002,
  // f 1/1/1 2/2/1 3/3/1 4/4/1 
  0.5016, 0.7508,
  0.5016, 1.002,
  0.2504, 1.002,
  // f 5/5/2 6/6/2 7/7/2 8/8/2 
  0.5016, 0.4996,
  0.5016, 0.2484,
  0.2504, 0.2484,
  // f 5/5/2 6/6/2 7/7/2 8/8/2 
  0.5016, 0.4996,
  0.2504, 0.4996,
  0.2504, 0.2484,
  // f 1/9/3 4/10/3 6/6/3 5/5/3 
  0.7528, 0.4996,
  0.7528, 0.2484,
  0.5016, 0.2484,
  // f 1/9/3 4/10/3 6/6/3 5/5/3 
  0.7528, 0.4996,
  0.5016, 0.4996,
  0.5016, 0.2484,
  // f 4/11/4 3/12/4 7/7/4 6/6/4 
  0.5016, -0.00279999999999991,
  0.2504, -0.00279999999999991,
  0.2504, 0.2484,
  // f 4/11/4 3/12/4 7/7/4 6/6/4 
  0.5016, -0.00279999999999991,
  0.5016, 0.2484,
  0.2504, 0.2484,
  // f 3/13/5 2/14/5 8/8/5 7/7/5 
  -0.0008, 0.2484,
  -0.0008, 0.4996,
  0.2504, 0.4996,
  // f 3/13/5 2/14/5 8/8/5 7/7/5 
  -0.0008, 0.2484,
  0.2504, 0.2484,
  0.2504, 0.4996,
  // f 2/2/6 1/1/6 5/5/6 8/8/6 
  0.2504, 0.7508,
  0.5016, 0.7508,
  0.5016, 0.4996,
  // f 2/2/6 1/1/6 5/5/6 8/8/6 
  0.2504, 0.7508,
  0.2504, 0.4996,
  0.5016, 0.4996,
};

And my rendering code:

-(void)setup
{
    self.drawingMode = GL_TRIANGLES;
    vertexData = [NSMutableData dataWithBytes:boxVerts length:sizeof(float)*boxNumVerts*3];
    textureCoordinateData = [NSMutableData dataWithBytes:boxTexCoords length:sizeof(float)*boxNumVerts*2];
    //    vertexNormalData = [NSMutableData dataWithBytes:PrisonCellNormals length:sizeof(float)*PrisonCellNumVerts*3];
}

-(void)renderInScene:(FRPGScene *)_scene 
{
     if (texture != nil)
        {
            effect.texture2d0.envMode = GLKTextureEnvModeReplace;
            effect.texture2d0.target = GLKTextureTarget2D;
            effect.texture2d0.name = texture.name;
            [effect.texture2d0 setEnabled:YES];
        }

        effect.transform.modelviewMatrix = self.modelviewMatrix;
        effect.transform.projectionMatrix = _scene.projectionMatrix;

        [effect prepareToDraw];

        // setup
        glEnable(GL_BLEND);

        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

        glEnableVertexAttribArray(GLKVertexAttribPosition);

        glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 0, self.vertices);

        if (!useConstantColor)
        {
            glEnableVertexAttribArray(GLKVertexAttribColor);
            glVertexAttribPointer(GLKVertexAttribColor, 4, GL_FLOAT, GL_FALSE, 0, self.vertexColors);
        }

        if (texture != nil)
        {
            glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
            glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, 0, self.textureCoordinates);
        }

        glDrawArrays(drawingMode, 0, self.numVertices);

        glDisable(GL_BLEND);

        // teardown
        glDisableVertexAttribArray(GLKVertexAttribPosition);

        if (!useConstantColor)
        {
            glDisableVertexAttribArray(GLKVertexAttribColor);
        }

        if (texture != nil)
        {
            glDisableVertexAttribArray(GLKVertexAttribTexCoord0);
        }
}

UPDATE: The appDelegate function where i set up my context.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    EAGLContext *context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
    [EAGLContext setCurrentContext:context];

    GLKView *view = [[GLKView alloc] initWithFrame:[[UIScreen mainScreen] bounds] context:context];
    view.delegate = self; //Makes sure the views drawInRect is called

    FRPGViewController *controller = [[FRPGViewController alloc] init];
    controller.delegate = self;
    controller.view = view;

    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.rootViewController = controller;
    [self.window makeKeyAndVisible];

    scene = [[FRPGTestLevel alloc] init];

    //Set screen aspect ratio boundaries ipad 4:3 iphone 3:2
    CGRect rect = view.bounds;

    scene.left = -100.0f;
    scene.right = 100.0f;
    scene.bottom = -100.0f / (rect.size.width / rect.size.height); // -75.0..
    scene.top = 100.0f / (rect.size.width / rect.size.height); // 75.0..
    [scene setup];

    [controller setScene:scene];


    return YES;
}

My Scenes render function clears the buffer and calls the above renderInScene method on every object

-(void)render
{
     glClearColor(clearColor.r, clearColor.g, clearColor.b, clearColor.a);
     glClear(GL_COLOR_BUFFER_BIT);
     [object renderInScene:scene]; 
}  

Answer 1

You need to set up your depth buffer

GLuint _depthRenderBuffer;

- (void)setupDepthBuffer
{
    glGenRenderbuffers(1, &_depthRenderBuffer);
    glBindRenderbuffer(GL_RENDERBUFFER, _depthRenderBuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, self.frame.size.width, self.frame.size.height);
}

and then add to your frame buffer

glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, _depthRenderBuffer);