Scale / Move CC3Backdrop or CC3ClipScpaceNode

[zadanlavey]

Hello;

I have created a CC3ClipScpaceNode to frecuently render a texture on the CC3Scene background (Like the CC3Backdrop). I'm just updating the "texture" property from the CC3ClipScpaceNode and wokrs OK.

My problem is when I try to scale or move the CC3ClipScpaceNode.

The API mention that it's like any other CC3Node with the property "shouldDrawInClipSpace" set to YES, and only respond to X and Y modifications (Because its a plane), but doesn't get updated....

Here is the code:

CC3ClipSpaceNode * clip = [CC3ClipSpaceNode  nodeWithTexture:[CC3Texture textureFromFile: @"BrushedSteel.png"]];

[self addChild: clip];

clip.location = cc3v(1.0, 2.0, 0.0); // Normalized to 2.0

clip.scale = cc3v(1.0, 2.0, 0.0); // Normalized

Is this the normal behavior or I need something else on my set-up?

Thanks in advance.

zL

[billhollings]

@zadanlavey

I'm not sure what you are trying to accomplish.

By default, the clip-space node uses the vertex shader CC3ClipSpaceTexturable.vsh, which does not make use of any transform matrices (have a look at the CC3ClipSpaceTexturable.vsh source to see this). So, it will ignore all changes to any transform properties on the clip-space node.

If you need to move it around, create a modified shader, that does take the transforms into account, and apply it to the node.

You can also create a backdrop within the scene using a large plane node, or skybox.

...Bill

[zadanlavey]

Hello @billhollings;

I want to render a video as texture for the backdrop or CC3ClipScpaceNode. The problem is that the video has an aspect ratio of 4:3 and the CC3ClipScpaceNode deforms this when the node it's adapted to the screen viewSize, that's why I need to scale and move this CC3ClipScpaceNode, to increase one side and get the correct aspect ratio based on the video and move it if is needed to center a particular area of this node "Streaming" the video.

Is there another option without creating a modified shader?...

zL

[billhollings]

@zadanlavey

A clip-space node has a 4-vertex mesh with corners at (+/- 1, +/- 1, 0), which covers the full surface.

You should be able to use the setVertexLocation:at: method to modify these corners to whatever you want. You'll have to calculate the appropriate values based on the aspect ratio of your video and the aspect ratio of the screen (which will be different for different devices).

...Bill

[zadanlavey]

Thank you @billhollings!!

setVertexLocation:at: method did the trick. I ended using the CC3Scene backdrop property instead the CC3ClipScpaceNode because the zOrder didn't affected the CC3ClipScpaceNode and the backdrop property worked as I expected.

It was easy to maintain the aspect ratio once I understood how the backdrop property works.

This is the code I used:

-(void) configureVideoBackdrop {

self.backdrop = [CC3Backdrop nodeWithTexture: [CC3Texture textureFromFile: @"BrushedSteel.png"]];

// Use the default backdrop for iPad
[self.backdrop setVertexLocation:cc3v(-1.3, -1.85125, 0.0) at:0];
[self.backdrop setVertexLocation:cc3v(1.3, -1.85125, 0.0) at:1];
[self.backdrop setVertexLocation:cc3v(-1.3, 1.85125, 0.0) at:2];
[self.backdrop setVertexLocation:cc3v(1.3, 1.85125, 0.0) at:3];

}

Thanks again Bill!

zL