Is it possible to have multiple viewports?

[Tomas]

Hi, wonder is it possible to have multiple viewports?

[AggrorJorn]

Pressing f12 switches from single viewport to 4 viewports.

[Tomas]

Im actually looking for viewport for minimap, so i can scale map and still have the bounds and see the 3d view. Maybe there are other workarounds for that?

[Ma-Shell]

You will need to use multiple buffers and render the scene twice. You can use a pivot (I named it "map_viewport") to mark the position and rotation of the camera for the map. See the following C++-Example to see, how to do that.

If you're using LUA, it should be pretty straight-forward to translate this.

 

Buffer* map_buf;
Pivot* map_viewport;

bool App::Start()
{
   ...
   map_buf = Buffer::Create(100, 100, 1, 1, 0);
   map_viewport = Pivot::Create();
}

bool App::Loop()
{
   ...
   // Clear both buffers
   context->Clear();
   map_buf->Clear();
   // Save the current position and rotation
   Mat4 cur_mat = camera->GetMatrix(true);
   // Set the camera's position and rotation to the pivot's
   camera->SetMatrix(map_viewport->GetMatrix(true), true);

   // Render the world to the map-Buffer
   context->Disable();
   map_buf->Enable();
   world->Render();
   // Restore the position and rotation
   camera->SetMatrix(cur_mat, true);

   // Render the world to the context-Buffer
   context->Enable();
   map_buf->Disable();
   world->Render();

   // Draw the map over the context
   int blendMode = context->GetBlendMode();
   context->SetBlendMode(Blend::Solid);
   context->DrawImage(map_buf->GetColorTexture(), 0, 0, 100, 100);
   context->SetBlendMode(blendMode);

   context->Sync(false);
   return true;    
}

 

Edit: Changed the code to use the transformation-Matrices instead of setting position and rotation, as this should be more efficient

 

Edit2: Changed the blend-mode to Blend::Solid instead of Blend::Alpha

Edited January 27, 2017 by Ma-Shell

[Rick]

Like Ma said you can think of it as moving the camera to a spot and taking a picture (this new buffer) from that location then moving the camera back to your player for the normal game to play. Now you have this image/buffer that you can draw anywhere on the screen or as a texture on a model. This moving the camera to a spot, taking a picture from that spot, and moving back to the player happens every frame for video or once for a static image.

[Tomas]

Thanks guys. Need to study and try this...

What if to have 2 cameras and use one as usual and other one for map?

[Rick]

2 cameras have caused issues for ppl in the past. It's probably best to avoid doing that but you can try if you like. I think in that case you have to hide and show both be dude I believe you can only have one active camera at a time.

[Tomas]

I would say 2 cameras would be less costly

[Rick]

I think you'll find other issues with it but give it s go. Do a search on the forums about multiple cameras as others have gone down the 2 camera path and learn from them.

[Ma-Shell]

Even with two cameras you would need to go through all this buffer-swapping-stuff and render the scenery twice. The reason for this is that you can only render the world to the currently enabled buffers. Also I don't know, how/whether it is even possible to switch the currently rendered camera.

 

In order to decrease the costs of this you could do something like changing to a less costly render-mode for the map and decreasing the update-frequency, by only performing the rendering to the map-buffer, if at least X milliseconds have passed since the last rendering.

Edited January 27, 2017 by Ma-Shell

[Ma-Shell]

Well, actually I just found, that you can call camera->Render() instead of world->Render() (though this isn't documented and thus probably not available in LUA) and you can set a Render-Target. This means, you can actually simplify that a bit:

 

Buffer* map_buf;
Camera* map_cam;
bool App::Start()
{
    ...
    map_buf = Buffer::Create(100, 100, 1, 1, 0);
    map_cam = Camera::Create();
    map_cam->SetRenderTarget(map_buf->GetColorTexture());
}
bool App::Loop()
{
    ...
    // Clear both buffers
    context->Clear();
    map_buf->Clear();

    // Render both cameras
    camera->Render();
    map_cam->Render();

    // Draw the map over the context
    int blendMode = context->GetBlendMode();
    context->SetBlendMode(Blend::Solid);
    context->DrawImage(map_buf->GetColorTexture(), 0, 0, 100, 100);
    context->SetBlendMode(blendMode);
    context->Sync(false);
    return true;   
}

 

This kind of cleans the rendering-function a bit.

[Tomas]

Finally got it working. A bit laggy, but working. Theres my code:

 

Script.buffer=0
Script.mapcam=0
function Script:Start()
....
self.camera=Camera:Create()
self.camera:SetRotation(0,0,0)
self.camera:SetPosition(self.entity:GetPosition(true)+Vec3(0,1.8,0))
self.buffer = Buffer:Create(100, 100, 1, 1, 0)
self.mapcam = Camera:Create()
self.mapcam:SetRenderTarget(self.buffer:GetColorTexture())
end
function Script:UpdateWorld()
....
local buff=Buffer:GetCurrent()
Buffer:SetCurrent(self.buffer)
world:Render()
Buffer:SetCurrent(buff)
end
function Script:PostRender(context)
....
context:DrawImage(self.buffer:GetColorTexture(),0,0,100,100)
end

 

Didnt managed to get "camera:Render()" to work. Any ideas? The code actually renders same scene..

[Ma-Shell]

Yeah, as I said, the function is not documented and thus probably not exported to LUA. This means, you actually have no way to choose the rendered camera and should therefore use a pivot to mark the position of the second camera instead, like I did in my first post.

In your UpdateWorld()-function, you then have to swap the position and the buffers and render. Try it like this:

Script.buffer=0
Script.mapcam=0
function Script:Start()
   ....
   self.camera=Camera:Create()
   self.camera:SetRotation(0,0,0)
   self.camera:SetPosition(self.entity:GetPosition(true)+Vec3(0,1.8,0))
   self.buffer = Buffer:Create(100, 100, 1, 1, 0)
   self.mapcam = Pivot:Create()
end
function Script:UpdateWorld()
   ....
   local buff=Buffer:GetCurrent()
   local mat = self.camera:GetMatrix()
   self.camera:SetRenderTarget(self.buffer:GetColorTexture())
   self.camera:SetMatrix(self.mapcam:GetMatrix())
   world:Render()
   self.camera:SetRenderTarget(buf:GetColorTexture())
   self.camera:SetMatrix(mat)
end
function Script:PostRender(context)
   ....
   context:DrawImage(self.buffer:GetColorTexture(),0,0,100,100)
end

[Tomas]

Ok guys, thanks for help. Not working for me. I found another solution:

http://www.leadwerks.com/werkspace/topic/12537-drawing-a-section-of-a-2d-texture-setting-uv-coords/#entry90453