Question

I m 试图根据果树苗进行简单的油漆应用。为了打上一条线,GLPaint用粗体字标出一系列点。随着开放式GL的bl化,与甲型六氯环己烷相比,该线的每一点都与以前的点混在一起。我想避免这种情况。例如,你将红色颜色 set为粉碎和甲型,为0.5,抽出一条线,所有线为单体col——与甲型0.5相重复,没有自发通道。我可以清楚地解释,但我希望大家理解我)

因此,第一个问题是我如何做到这一点?

我决定用目前的行文进行校正,不作混淆,然后将目前的形象翻开。该守则是:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
        CGRect  bounds = [mainView bounds];
         UITouch* touch = [[event touchesForView:mainView] anyObject];
        firstTouch = YES;       location = [touch locationInView:mainView];
        location.y = bounds.size.height - location.y;

         // Offscreen buffer
    glGenRenderbuffersOES(1, &brushFramebuffer);
        glBindFramebuffer(GL_FRAMEBUFFER_OES, brushFramebuffer);
        glGenRenderbuffers(1, &brushDepthBuffer);
        glBindRenderbuffer(GL_RENDERBUFFER, brushDepthBuffer);
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16_OES, backingWidth, backingHeight);
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rushDepthBuffer);

        GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
        if(status != GL_FRAMEBUFFER_COMPLETE) {
                NSLog(@"failed to make complete framebuffer object %x", status);
                return;
        }
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
        CGRect  bounds = [mainView bounds];
        UITouch* touch = [[event touchesForView:mainView] anyObject];
        if (firstTouch) {
                firstTouch = NO;
                previousLocation = [touch locationInView:mainView];
                previousLocation.y = bounds.size.height - previousLocation.y;
        }
         else {
                location = [touch locationInView:mainView];
                location.y = bounds.size.height - location.y;
                previousLocation = [touch previousLocationInView:mainView];
                previousLocation.y = bounds.size.height - previousLocation.y;
        }

        [self renderLineFromPoint:previousLocation toPoint:location];
}

 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
         CGRect bounds = [mainView bounds];
         UITouch* touch = [[event touchesForView:mainView] anyObject];
        if (firstTouch) {
                firstTouch = NO;
                previousLocation = [touch previousLocationInView:mainView];
                previousLocation.y = bounds.size.height - previousLocation.y;
                [self renderLineFromPoint:previousLocation toPoint:location];
         }

          // getting texture from buffer
        glBindTexture(GL_TEXTURE_2D, bufferTexture);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1024, 768, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, bufferTexture, 0);

        glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

        glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, viewRenderbuffer);

        // drawing texture to image
        CGFloat vertices[] = {backingWidth/2, backingHeight/2};

        glVertexPointer(2, GL_FLOAT, 0, vertices);
        glDrawArrays(GL_POINTS, 0, 1);

        glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);

        [context presentRenderbuffer:GL_RENDERBUFFER_OES];
}
- (void) renderLineFromPoint:(CGPoint)start toPoint:(CGPoint)end {
        [EAGLContext setCurrentContext:context];
        glBindFramebufferOES(GL_FRAMEBUFFER_OES, brushFramebuffer);
        glBindTexture(GL_TEXTURE_2D, brushTexture);
          /// .... then drawing a line from "start" to "end"
}

The second question is: this code draws only draws brush texture to the center of screen, what am I doing wrong?

Answer 1

如何用线(没有碎.):简单地使用深度试验(清晰的深度缓冲,对L_NOT_EQUAL的深度 f,或将其保留在GL_LESS上),以避免把同一位置上两度。然而,这不会带来更为复杂的rush忙。

你的法典有若干主要缺陷。首先,如果你想向使用FBO的传票,你需要在你向缓冲站做任何事之前,打上冰川。因此,在白 touch的行动顺序如下:

glGenRenderbuffersOES(1, &brushFramebuffer);
glBindFramebuffer(GL_FRAMEBUFFER_OES, brushFramebuffer);
// creates FBO

glGenRenderbuffers(1, &brushDepthBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, brushDepthBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16_OES, backingWidth, backingHeight);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rushDepthBuffer);
// creates and attaches RB for depth

glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, bufferTexture, 0);
// attaches texture to render to. now we re ready.

其次,你不把 gl光2D()引向来,这将会消除迄今为止对案文所做的一切。叫 gl冰川(GL_TEXance_2D, GL_TEXpoli_MIN_FILTER, GL_LINEAR);但是,你最好能把这条线移到你制造缓冲创伤的那部分。为了停止推 frame,有人简单说:

glBindFramebufferOES(GL_FRAMEBUFFER_OES, 0);

文本载有在FBO积极运行期间所展示的形象,并转回屏幕(申请表)。

现在,由于你正在利用ture,你需要:

glBindTexture(GL_TEXTURE_2D, bufferTexture);

之后,你刚刚完成了充分筛选:

CGFloat vertices[] = {0, 0,
                      backingWidth, 0,
                      backingWidth, backingHeight,
                      0, backingHeight};
CGFloat texCoords[] = {0, 0,
                      1, 0,
                      1, 1,
                      0, 1,};
glVertexPointer(2, GL_FLOAT, 0, vertices);
glTexCoordPointer(2, GL_FLOAT, 0, texCoords);
glDrawArrays(GL_QUADS, 0, 4);

......

在LineFromPoint()中,不需要打电话。

glBindFramebufferOES(GL_FRAMEBUFFER_OES, brushFramebuffer);

因为它已受影响。但是,它赢得了一定的伤害。

还有一件事——你们应当确保,光顾、触及和触动真正地来到这里。我不敢肯定这一点。

友情链接