ZGameEditor forum

Posted: **Wed Feb 16, 2022 2:43 pm**

The documentation is sparse

http://www.zgameeditor.org/index.php/ComponentRef/Light

and I did not find any zgeproj-file nor another tutorial or example
that is using the ZGE-Light component.

Can someone demonstrate the usage?

My attempts to add lights did not change the scene at all.

What would be needed?

Thanks for some advice.

Cheers

Andreas

Posted: **Wed Feb 16, 2022 3:10 pm**

Hi Andreas,

ab2 wrote: ↑Wed Feb 16, 2022 2:43 pmCan someone demonstrate the usage?

Here's a simple demonstration of a white cube being lit by 3 differently colored point lights ( red, green and blue ).

Code: Select all

<?xml version="1.0" encoding="iso-8859-1" ?>
<ZApplication Name="App" Caption="ZGameEditor application" AmbientLightColor="0 0 0 1" FileVersion="2">
  <OnLoaded>
    <SpawnModel Model="Box"/>
  </OnLoaded>
  <OnUpdate>
    <ZExpression>
      <Expression>
<![CDATA[// Animate all 3 lights

float t = App.Time/8;

RedLight.Position.X = cos(t*3)*4;
RedLight.Position.Z = sin(t*3)*4;

GreenLight.Position.Y = cos(t*4)*4;
GreenLight.Position.Z = sin(t*4)*4;

BlueLight.Position.X = cos(t*5)*4;
BlueLight.Position.Y = sin(t*5)*4;]]>
      </Expression>
    </ZExpression>
  </OnUpdate>
  <OnRender>
    <UseMaterial Material="NodeMaterial"/>
    <Repeat Name="NodeRepeat" Count="3" WhileExp="//">
      <OnIteration>
        <ZExpression>
          <Expression>
<![CDATA[// Render light "representation" nodes for demonstation purposes

switch(NodeRepeat.Iteration)
{
  case 0:
    NodeColor.Color = RedLight.Color;
    NodeTransform.Translate = RedLight.Position;
    break;

  case 1:
    NodeColor.Color = GreenLight.Color;
    NodeTransform.Translate = GreenLight.Position;
    break;

  case 2:
    NodeColor.Color = BlueLight.Color;
    NodeTransform.Translate = BlueLight.Position;
    break;
}]]>
          </Expression>
        </ZExpression>
        <RenderSetColor Name="NodeColor" Color="0 0 1 1"/>
        <RenderTransformGroup Name="NodeTransform">
          <Children>
            <RenderMesh Mesh="NodeMesh"/>
          </Children>
        </RenderTransformGroup>
      </OnIteration>
    </Repeat>
  </OnRender>
  <Lights>
    <Light Name="RedLight" Color="1 0 0 1" Kind="1"/>
    <Light Name="GreenLight" Color="0 1 0 1" Kind="1"/>
    <Light Name="BlueLight" Color="0 0 1 1" Kind="1"/>
  </Lights>
  <Content>
    <Model Name="Box" RotationVelocity="0.1 0.2 0">
      <OnRender>
        <UseMaterial Material="BoxMaterial"/>
        <RenderMesh Mesh="BoxMesh"/>
      </OnRender>
    </Model>
    <Mesh Name="BoxMesh">
      <Producers>
        <MeshBox/>
      </Producers>
    </Mesh>
    <Material Name="BoxMaterial"/>
    <Mesh Name="NodeMesh">
      <Producers>
        <MeshSphere Scale="0.25 0.25 0.25" ZSamples="3" RadialSamples="4"/>
      </Producers>
    </Mesh>
    <Material Name="NodeMaterial" Shading="2" Light="0"/>
  </Content>
</ZApplication>

K

Posted: **Fri Feb 18, 2022 11:34 am**

Thank you for your vivid demonstration.

So lights by itself are invisible objects and
the in the example attached nodes can be used
to visualize them.

Can a spot-light effect like in a theatre
with a sharp radial illumnination on an
object be achived?

Or do you know of a good demonstration / page
what light type (spot, point, directional) to use
for what effect on a scene or object and how it should look like?

Many thanks

A

Posted: **Fri Feb 18, 2022 12:11 pm**

Hi Andreas,

ab2 wrote: ↑Fri Feb 18, 2022 11:34 amSo lights by itself are invisible objects and the in the example attached nodes can be used to visualize them.

Yea, i just added the "nodes" so it's easier to understand what's going on.

ab2 wrote: ↑Fri Feb 18, 2022 11:34 amCan a spot-light effect like in a theatre with a sharp radial illumnination on an object be achived?

Yes, but you probably want to use shaders for that. When you use the fixed-function pipeline light is calculated at vertex level, so you'd need high-poly meshes for the effect to look good. Here's a simple example of that using a single spotlight. You can control the "softness" of the spotlight by moving your mouse up/down, and you can toggle the shading style of the scene by pressing 1/2/3/4 on your keyboard ( for debugging purposes ).

Code: Select all

<?xml version="1.0" encoding="iso-8859-1" ?>
<ZApplication Name="App" Caption="ZGameEditor application" AmbientLightColor="0 0 0 1" CameraPosition="0 10 10" CameraRotation="0.125 0 0" MouseVisible="255" FileVersion="2">
  <OnUpdate>
    <ZExpression>
      <Expression>
<![CDATA[// Control spot "softness"

SpotLight.SpotExponent = (1-App.MousePosition.Y)*22.5;

// Animate spot light

float a = sin(App.Time*2)/4;

SpotLight.SpotDirection.X =  sin(a);
SpotLight.SpotDirection.Y = -cos(a);

SpotLight.Position.Y = 8+sin(App.Time/3)*4;]]>
      </Expression>
    </ZExpression>
    <KeyPress Name="ShadingKey" Keys="1234">
      <OnPressed>
        <ZExpression>
          <Expression>
<![CDATA[// Switch scene shading

SceneMaterial.Shading = ShadingKey.KeyIndex;]]>
          </Expression>
        </ZExpression>
      </OnPressed>
    </KeyPress>
  </OnUpdate>
  <OnRender>
    <UseMaterial Material="SceneMaterial"/>
    <RenderMesh Mesh="SceneMesh"/>
  </OnRender>
  <Lights>
    <Light Name="SpotLight" Color="1 1 1 1" Kind="2" SpotDirection="0 0 0" SpotCutoff="22.5"/>
  </Lights>
  <Content>
    <Mesh Name="SceneMesh">
      <Producers>
        <MeshBox Scale="4 4 1" XCount="15" YCount="15" Grid2DOnly="255"/>
        <MeshTransform Position="0 -1 0" Rotation="-0.25 0 0"/>
        <MeshBox XCount="3" YCount="3"/>
        <MeshCombine/>
      </Producers>
    </Mesh>
    <Material Name="SceneMaterial"/>
  </Content>
</ZApplication>

K

Posted: **Fri Feb 18, 2022 5:02 pm**

Thanks. That is the tutorial style i really like an can handle
pretty good.

Sorry that I experiment with it .. probably with to few understanding ..
but why in this project gets the Light Color overwritten by the
Scene-Material Color?

Posted: **Fri Feb 18, 2022 5:21 pm**

Hi Andreas,

ab2 wrote: ↑Fri Feb 18, 2022 5:02 pmSorry that I experiment with it .. probably with to few understanding .. but why in this project gets the Light Color overwritten by the Scene-Material Color?

It doesn't. When you for example change SceneMaterial.Color from white into yellow the scene ( box & floor ) appears yellow because at that point it's a yellow box & floor lit by a white light. But if you then for example change the SpotLight.Color from white into red, the yellow box & floor appears red.

The result is always a combination of the object's color and the color of the emitted light.

K

Posted: **Sat Feb 19, 2022 1:42 am**

Sorry without additional tries i choose first yellow for the spotlight and then
orange for the scene. That was a bad Example.

ZGameEditor forum

How to use the ZGE-Light component?

How to use the ZGE-Light component?

Re: How to use the ZGE-Light component?

Re: How to use the ZGE-Light component?

Re: How to use the ZGE-Light component?

Re: How to use the ZGE-Light component?

Re: How to use the ZGE-Light component?

Re: How to use the ZGE-Light component?