Question

我的应用使用OpenGL ES渲染用户绘制签名的屏幕。我的代码已经工作了3年以上，但升级到Xcode 9后，我在绘制的线条中得到了一个奇怪的颜色变化（在模拟器和设备上）。这些线条过去常有纯红色，绿色或蓝色，现在混合了灰色/黑色线条我不太了解OpenGL，我的代码是从示例应用程序和教程中组合而成的。

可能导致此更改的原因是什么？

这是升级到Xcode 9后的图纸：

改变颜色的代码：

// Change the brush color
- (void)changeBrushColor:(NSString *) newColor
{
    SEL setcolor = NSSelectorFromString(newColor);
    UIColor *nColor =  [UIColor performSelector:setcolor];

    CGColorRef color = nColor.CGColor;
    const CGFloat *components = CGColorGetComponents(color);

    brushColor[0] = (GLfloat) components[0];
    brushColor[1] =  (GLfloat) components[1];
    brushColor[2] =  (GLfloat) components[2];
    brushColor[3] =  (GLfloat) components[3];

    if (initialized) {
        glUseProgram(program[PROGRAM_POINT].id);
        glUniform4fv(program[PROGRAM_POINT].uniform[UNIFORM_VERTEX_COLOR], 1, brushColor);
    }
}

要绘制的代码： CGPoint newMidPoint = CGPointMake（x / scale，y / scale）;

    [currentStroke insertObject:[NSValue valueWithCGPoint:newMidPoint] atIndex:2];
    [currentStroke removeObjectAtIndex:0];
    [currentStroke removeObjectAtIndex:0];
    //NSLog(@" after draw currentstroke %@: ", currentStroke);


    // Load data to the Vertex Buffer Object & Draw it
    //glUseProgram(program[PROGRAM_POINT].id);
    //glBindBuffer(GL_ARRAY_BUFFER, vboId);
    glBufferData(GL_ARRAY_BUFFER, vertexCount*2*sizeof(GLfloat), vertexBuffer, GL_DYNAMIC_DRAW);
    //glEnableVertexAttribArray(ATTRIB_VERTEX);
    glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, GL_FALSE, 0, 0);

    // Draw
    glDrawArrays(GL_POINTS, 0, (int)vertexCount);

    // Display the buffer
    //glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
    [context presentRenderbuffer:GL_RENDERBUFFER];

初始化代码：

       - (BOOL)initGL
        {
            // Generate IDs for a framebuffer object and a color renderbuffer
            glGenFramebuffers(1, &viewFramebuffer);
            g

    lGenRenderbuffers(1, &viewRenderbuffer);

            glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);
            glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
            // This cal

l associates the storage for the current render buffer with the EAGLDrawable (our CAEAGLLayer)
        // allowing us to draw into a buffer that will later be rendered to screen wherever the layer is (which corresponds with our view).
        [context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(id<EAGLDrawable>)self.layer];
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, viewRenderbuffer);

        glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);
        glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);


        if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        {
            NSLog(@"failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));
            return NO;
        }

        // Setup the view port in Pixels
        glViewport(0, 0, backingWidth, backingHeight);

        // Create a Vertex Buffer Object to hold our data
        glGenBuffers(1, &vboId);

        // Load the brush texture
        brushTexture = [self textureFromName:@"brush"];

        // Load shaders
        [self setupShaders];

        // Enable blending and set a blending function appropriate for premultiplied alpha pixel data
        glEnable(GL_BLEND);
        glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

        //moved from draw
        glUseProgram(program[PROGRAM_POINT].id);
        glBindBuffer(GL_ARRAY_BUFFER, vboId);
        glEnableVertexAttribArray(ATTRIB_VERTEX);

    //    //***** for testing ******
    //    [self sample];
    //    //***** for testing ******

        return YES;
    }

Answer 1

我终于找到了解决问题的方法。我使用了64x64和32x32的画笔纹理图像，解决了这个问题。我不知道为什么会这样，并且仍然会对导致问题的原因提出一些意见。

用xcode 9改变颜色的颜色

1 个答案: