c++ - 渲染时不出现 3D 模型

Question

我正在使用 Vuforia将 3D 模型放置在图像目标上。我创建了一个适用于 Android 和 iOS 的通用 C++ 解决方案。它适用于 Android，但我无法让 3D 模型出现在 iOS 中。它完美地跟踪图像目标，但没有 3D 模型的迹象。可以找到我正在使用的 3D 模型 here .

我是这样的:

每次需要渲染屏幕时，Vuforia 都会调用此方法:

- (void)renderFrameQCAR
{
    [self setFramebuffer];
    [[ObjectController getInstance] getObjectInstance]->renderFrame();
    [self presentFramebuffer];
}

这是 setFramebuffer 方法 (Objective-C++):

- (void)setFramebuffer
{
    if (context) {
        [EAGLContext setCurrentContext:context];

        if (!defaultFramebuffer) {
            [self performSelectorOnMainThread:@selector(createFramebuffer) withObject:self waitUntilDone:YES];
        }

#ifdef USE_OPENGL1
        glBindFramebufferOES(GL_FRAMEBUFFER_OES, defaultFramebuffer);
#else
        glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebuffer);
#endif
    }
}

这是 renderFrame 方法 (C++):

void IDRObject::renderFrame()
{
    // Clear color and depth buffer
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // Get the state from QCAR and mark the beginning of a rendering section
    QCAR::State state = QCAR::Renderer::getInstance().begin();

    // Explicitly render the Video Background
    QCAR::Renderer::getInstance().drawVideoBackground();

#ifdef DEVICE_OPENGL_1
    // Set GL11 flags:
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_NORMAL_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);

    glEnable(GL_TEXTURE_2D);
    glDisable(GL_LIGHTING);

#endif

    glEnable(GL_DEPTH_TEST);

    // We must detect if background reflection is active and adjust the culling direction.
    // If the reflection is active, this means the post matrix has been reflected as well,
    // therefore standard counter clockwise face culling will result in "inside out" models.
    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);
    if(QCAR::Renderer::getInstance().getVideoBackgroundConfig().mReflection == QCAR::VIDEO_BACKGROUND_REFLECTION_ON)
        glFrontFace(GL_CW);  //Front camera
    else
        glFrontFace(GL_CCW);   //Back camera

    SampleUtils::checkGlError("gl start setup stuff");
    // Did we find any trackables this frame?
    for(int tIdx = 0; tIdx < state.getNumTrackableResults(); tIdx++)
    {
        // Get the trackable:
        const QCAR::TrackableResult* result = state.getTrackableResult(tIdx);
        const QCAR::Trackable& trackable = result->getTrackable();
        QCAR::Matrix44F modelViewMatrix = QCAR::Tool::convertPose2GLMatrix(result->getPose());

        // Choose the texture based on the target name:
        int textureIndex;
        if (strcmp(trackable.getName(), "chips") == 0)
        {
            textureIndex = 0;
        }
        else if (strcmp(trackable.getName(), "stones") == 0)
        {
            textureIndex = 1;
        }
        else
        {
            textureIndex = 2;
        }

        const Texture* const thisTexture = textures[textureIndex];

#ifdef DEVICE_OPENGL_1
        // Load projection matrix:
        glMatrixMode(GL_PROJECTION);
        glLoadMatrixf(projectionMatrix.data);

        // Load model view matrix:
        glMatrixMode(GL_MODELVIEW);
        glLoadMatrixf(modelViewMatrix.data);
        glTranslatef(0.f, 0.f, kObjectScale);
        glScalef(kObjectScale, kObjectScale, kObjectScale);

        // Draw object:
        glBindTexture(GL_TEXTURE_2D, thisTexture->mTextureID);
        glTexCoordPointer(2, GL_FLOAT, 0, (const GLvoid*) &teapotTexCoords[0]);
        glVertexPointer(3, GL_FLOAT, 0, (const GLvoid*) &teapotVertices[0]);
        glNormalPointer(GL_FLOAT, 0,  (const GLvoid*) &teapotNormals[0]);
        glDrawElements(GL_TRIANGLES, NUM_TEAPOT_OBJECT_INDEX, GL_UNSIGNED_SHORT,
                   (const GLvoid*) &teapotIndices[0]);

#else


        QCAR::Matrix44F modelViewProjection;

        SampleUtils::translatePoseMatrix(0.0f, 0.0f, kObjectScale, &modelViewMatrix.data[0]);
        SampleUtils::scalePoseMatrix(kObjectScale, kObjectScale, kObjectScale, &modelViewMatrix.data[0]);
        SampleUtils::multiplyMatrix(&projectionMatrix.data[0], &modelViewMatrix.data[0], &modelViewProjection.data[0]);

        glUseProgram(shaderProgramID);

        glVertexAttribPointer(vertexHandle, 3, GL_FLOAT, GL_FALSE, 0, (const GLvoid*) &teapotVertices[0]);
        glVertexAttribPointer(normalHandle, 3, GL_FLOAT, GL_FALSE, 0, (const GLvoid*) &teapotNormals[0]);
        glVertexAttribPointer(textureCoordHandle, 2, GL_FLOAT, GL_FALSE, 0, (const GLvoid*) &teapotTexCoords[0]);

        glEnableVertexAttribArray(vertexHandle);
        glEnableVertexAttribArray(normalHandle);
        glEnableVertexAttribArray(textureCoordHandle);

        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, thisTexture->mTextureID);

        glUniformMatrix4fv(mvpMatrixHandle, 1, GL_FALSE, (GLfloat*)&modelViewProjection.data[0] );
        glUniform1i(texSampler2DHandle, 0 /*GL_TEXTURE0*/);
        glDrawElements(GL_TRIANGLES, NUM_TEAPOT_OBJECT_INDEX, GL_UNSIGNED_SHORT, (const GLvoid*) &teapotIndices[0]);

        LOG("Tracking awesome targets.\n");
        SampleUtils::checkGlError("ImageTargets renderFrame\n");
#endif

    }

    glDisable(GL_DEPTH_TEST);
    glDisable(GL_CULL_FACE);

#ifdef DEVICE_OPENGL_1
    glDisable(GL_TEXTURE_2D);
    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_NORMAL_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
#else
    glDisableVertexAttribArray(vertexHandle);
    glDisableVertexAttribArray(normalHandle);
    glDisableVertexAttribArray(textureCoordHandle);
#endif

    QCAR::Renderer::getInstance().end();
}

最后一个 presentFrameBuffer (Objective-C++):

- (BOOL)presentFramebuffer
{
    BOOL success = FALSE;

    if (context) {
        [EAGLContext setCurrentContext:context];

#ifdef USE_OPENGL1
        glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer);
#else
        glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
#endif

        success = [context presentRenderbuffer:GL_RENDERBUFFER];
    }

    return success;
}

Answer 1

事实证明，projectionMatrix 从未被设置。

我错过了以下电话:

// Cache the projection matrix:
const QCAR::CameraCalibration& cameraCalibration = QCAR::CameraDevice::getInstance().getCameraCalibration();
projectionMatrix = QCAR::Tool::getProjectionGL(cameraCalibration, 2.0f, 2500.0f);

它们最初位于 Vuforia 的 ImageTarget 示例中的 startCamera 方法中。