# Camera COMP

## Summary

The Camera Component is a 3D object that acts like real-world cameras. You view your scene through it and render from their point of view. A Camera Component can be attached or linked to any other 3D Component in a 3D hierarchy.

## Parameters - Xform Page

The Xform parameter page controls the object component's transform in world space.

Transform Order `xord` - The menu attached to this parameter allows you to specify the order in which the changes to your Component will take place. Changing the Transform order will change where things go much the same way as going a block and turning east gets you to a different place than turning east and then going a block. In matrix math terms, if we use the 'multiply vector on the right' (column vector) convention, a transform order of Scale, Rotate, Translate would be written as `translate * rotate * scale * vector`.

Rotate Order `rord` - The rotational matrix presented when you click on this option allows you to set the transform order for the Component's rotations. As with transform order (above), changing the order in which the Component's rotations take place will alter the Component's final position.

Translate / Rotation / Scale `t[xyz] r[xyz] s[xyz]` - The three fields allow you to specify the amount of movement along any of the three axes; the amount, in degrees, of rotation around any of the three axes; and a non-uniform scaling along the three axes. As an alternative to entering the values directly into these fields, you can modify the values by manipulating the Component in the Viewport with the Select & Transform state.

Pivot `p[xyz]` - The Pivot point edit fields allow you to define the point about which a Component scales and rotates. Altering the pivot point of a Component produces different results depending on the transformation performed on the Component.

For example, during a scaling operation, if the pivot point of an Component is located at `-1, -1, 0` and you wanted to scale the Component by `0.5` (reduce its size by 50%), the Component would scale toward the pivot point and appear to slide down and to the left.

In the example above, rotations performed on an Component with different pivot points produce very different results.

Uniform Scale `scale` - This field allows you to change the size of an Component uniformly along the three axes.

Note: Scaling a camera's channels is not generally recommended. However, should you decide to do so, the rendered output will match the Viewport as closely as possible when scales are involved.

Constrain To `constrain` - Allows the location of the object to be constrained to any other object whose path is specified in this parameter.

Look At `lookat` - Allows you to orient your Component by naming the Component you would like it to Look At, or point to. Once you have designated this Component to look at, it will continue to face that Component, even if you move it. This is useful if, for instance, you want a camera to follow another Component's movements. The Look At parameter points the Component in question at the other Component's origin.

Tip: To designate a center of interest for the camera that doesn't appear in your scene, create a Null Component and disable its display flag. Then Parent the Camera to the newly created Null Component, and tell the camera to look at this Component using the Look At parameter. You can direct the attention of the camera by moving the Null Component with the Select state. If you want to see both the camera and the Null Component, enable the Null Component's display flag, and use the Select state in an additional Viewport by clicking one of the icons in the top-right corner of the TouchDesigner window.

Look At Up Vector `lookup` - When specifying a Look At, it is possible to specify an up vector for the lookat. Without using an up vector, it is possible to get poor animation when the lookat Component passes through the Y axis of the target Component.

• Don't Use Up Vector - Use this option if the look at Component does not pass through the Y axis of the target Component.
• Use Up Vector - This precisely defines the rotates on the Component doing the looking. The Up Vector specified should not be parallel to the look at direction. See Up Vector below.
• Use Quaternions - Quaternions are a mathematical representation of a 3D rotation. This method finds the most efficient means of moving from one point to another on a sphere.

Path SOP `pathsop` - Names the SOP that functions as the path you want this Component to move along. For instance, you can name an SOP that provides a spline path for the camera to follow.

Production Tip: For Smooth Motion Along a Path - Having a Component follow an animation path is simple. However, when using a NURBS curve as your path, you might notice that the Component speeds up and slows down unexpectedly as it travels along the path. This is usually because the CVs are spaced unevenly. In such a case, use the Resample SOP to redistribute the CVs so that they are evenly spaced along the curve. A caution however - using a Resample SOP can be slow if you have an animating path curve.

An alternative method is to append a Basis SOP to the path curve and change it to a `Uniform Curve`. This way, your Component will move uniformly down the curve, and there is no need for the Resample SOP and the unnecessary points it generates.

Roll `roll` - Using the angle control you can specify a Component's rotation as it animates along the path.

Position `pos` - This parameter lets you specify the Position of the Component along the path. The values you can enter for this parameter range from `0` to `1`, where `0` equals the starting point and `1` equals the end point of the path. The value slider allows for values as high as `10` for multiple "passes" along the path.

Orient Along Path `pathorient` - If this option is selected, the Component will be oriented along the path. The positive Z axis of the Component will be pointing down the path.

Up Vector `up` - When orienting a Component, the Up Vector is used to determine where the positive Y axis points.

Auto-Bank Factor `bank` - The Auto-Bank Factor rolls the Component based on the curvature of the path at its current position. To turn off auto-banking, set the bank scale to `0`.

## Parameters - Pre-Xform Page

The Pre-Xform parameter page applies a transform to the object component before the Xform page's parameters are applied. That is, it is the same as connecting a Null COMP as a parent of this node, and putting same transform parameters in there as you would in the Pre-Xform page. In terms of matrix math, if we use the 'multiply vector on the right' (column vector) convention, the equation would be `preXForm * xform * vector`.

Xform Matrix/CHOP/DAT `xformmatrixop` - This parameter can be used to transform using a 4x4 matrix directly. If a CHOP is used, the 16 elements of the matrix are taken from the first 16 channels of the CHOP. It only uses the first sample of each channel. The matrix data is laid out in such as way that the 13th, 14th and 15th channels contain the translation. This can be thought of as either column or row-major conventions, reading the channels column by column or row by row.

If a DAT is used it should be a 4x4 table with the desired matrix values in each cell. The translation should be in the last column, which means it is using the convention of multiplying vectors/points on the right of the matrix (like GLSL does). If you are converting from a Table DAT using a DAT to CHOP, you'll want to use a Transpose DAT to get the channels in the correct order. It applied to the Xform Matrix in the Pre-Xform page of all Object CHOPs and the Projection Matrix in the View page of Lights and Cameras.

A `tdu.Matrix` can also be directly specified. Example of using a `tdu.Matrix`:

```m = tdu.Matrix()
m.translate(5, 0, 0)
m.rotate(0, 45, 0)
someNode.store(‘xformMat’, m)
```

and in the node parameter you would put:

```me.fetch(‘xformMat’)
```

## Parameters - View Page

Projection `/projection` - A pop-up menu lets you choose from Perspective and Orthographic projection types. A third option Perpective to Ortho Blend enables the Projection Blend parameter below which can be used to blend between perspectives. A 4th option Custom Projection Matrix allows you to specify a custom 4x4 projection matrix using a CHOP or a DAT.

Projection Blend `/projectionblnd` - Blends between perspective projection and orthographic projection when the Projection parameter is set to Perspective to Ortho Blend.

Ortho Width `/orthowidth` - Only active if Orthographic is chosen from the Projection pop-up menu. This specifies the width of the orthographic projection.

Viewing Angle Method `/viewsanglemethod` - This menu determines which method is used to define the camera's angle of view.

• Horizontal FOV - Uses the FOV Angle parameter below to set the camera's angle of view horizontally.
• Vertical FOV - Uses the FOV Angle parameter below to set the camera's angle of view vertically.
• Focal Length and Aperture - Uses the Focal Length and Aperture parameters below to define the camera's angle of view.

FOV Angle `/fov` - The field of view (FOV) angle is the angular extend of the scene imaged by the camera.

Field of View and Throw Angle: The FOV would be:

FOV = arctan( (screenWidth / 2) / (distanceToScreen) ) * 2
FOV = arctan( 0.5 * (screenWidth / distanceToScreen) ) * 2

Throw is:

Throw = distanceToScreen / screenWidth
1/Throw = screenWidth / distanceToScreen

In terms of throw, it’s

FOV = arctan(0.5 * (1/Throw)) * 2
FOV = arctan(0.5 / Throw) * 2

Focal Length (in MM) `/focal` - The parameter sets the focal length of the lens, zooming in and out. Perspective is flattened or exaggerated depending on focal length. See FOV Angle parameter for relation of aperture, focal length and field of view angle. Some interesting distortion effects can be acheived with this parameter.

Aperture (in MM) `/aperture` - This value relates to the area through which light can pass for the camera.

Window X/Y `/winx /winy` - These parameters define the center of the window during the rendering process. The window parameter takes the view and expands it to fit the camera's field of vision. It is important to note that this action is independent of perspective. In other words, it acts as though you are panning the camera without actually moving the camera. The units for this parameter are normalized. That is a Window X of -0.5 will move the previous center of the image to the left edge of the render.

Window Size `/winsize` - The Window Size parameter specifies the dimensions for expanding the view. Similar to Window X / Y, this parameter creates a zoom effect by scaling the screen before rendering to the viewport.

Near / Far `/near /far` - This control allows you to designate the near and far clipping planes. Geometry closer / further away from the lens than these distances will not be visible.

NOTE:If geometry in your scene is producing z-depth artifacts, increase the resolution of the camera's z-depth buffer. To do this, decrease the difference between near and far clipping planes, starting with the near plane.

Window Roll `/winroll` - This parameter sets the amount, in degrees, the window area rolls. This can be set as a static value or as an aspect that changes over the course of the animation. The roll occurs about the centre of the window.

Matrix CHOP/DAT `/projmatrixop` - When Custom Projection Matrix is selected, this parameters should be filled in with either a CHOP or a DAT with a custom 4x4 projection matrix. If a CHOP is used the first sample of the first 16 channels of the CHOP are used to create a 4x4 matrix. The channels can be thought as being read row-by-row or column-by-column. If a DAT is given a 4x4 table should be used. The matrix convention used is column major, which means vectors/points are multiplied on the right of the matrix.

Custom Projection `/customproj` - Takes a DAT containing a GLSL shader to specify custom projection functions. Use this only with the built in MATs or GLSL MATs that are using GLSL version 3.3 or later. You must provide two functions in this shader. Both functions must be provided and return correct results for your rendering to work in all cases. As a starting point, here are the definitions for these functions that are used when custom ones are not provided.

``` vec4 TDSOPToProj(vec4 p)
{
vec4 projP = uTDMat.worldCamProj * p;
return projP;
}
vec4 TDCamToProj(vec4 p)
{
vec4 projP = uTDMat.proj * p;
return projP;
}
```

The other convenience variations of these functions such as `vec3 TDCamToProj(vec3 p)` will automatically call the correct one of either of the two above functions. You can use uniforms/samplers in this shader code by declaring them here and providing them in the GLSL page of the Render TOP.

## Parameters - Settings Page

Background Color `bgcolorr / bgcolorg / bgcolorb / bgcolora` - Sets the background color and alpha of the camera's view.

Fog - This menu determines the type of fog rendered in the viewport:
Linear fog uses the following equation:

Exponential fog uses the following equation:

Squared Exponential fog uses the following equation:

Fog Density `/fogdensity` - A value that specifies density or thickness, used in both exponential fog types. Only non-negative densities are accepted.

Fog Near `/fognear` - The starting distance of the fog. If geometry is closer to the camera than this distance, fog will not be calculated in the color of the geometry. Used in the linear fog equation.

Fog Far `/fogfar` - The far distance used in the linear fog equation.

Fog Color `/fogcolor[rgb]` - The color of the fog.

Fog Alpha `/fogalpha` - Used to control the background opacity of the scene.

Fog Map `/fogmap` - Use a TOP texture as a color map for the fog.

Camera Light Mask `/camlightmask` - Allows only specific lights to be used by this camera. This is used in conjunction with the Lights parameter in the Render TOP to determine what lights are used to illuminate the geometry. When this parameter is left blank, all lights specified in the Render TOP will be used. Lights specified in this parameter will limit the geometry's lighting with this camera to the light(s)specified assuming the light(s) is also listed in the Render TOP.

## Parameters - Render Page

The Display parameter page controls the component's material and rendering settings.

Material `material` - Selects a MAT to apply to the geometry inside.

Render `render` - Whether the Component's geometry is visible in the Render TOP. This parameter works in conjunction (logical AND) with the Component's Render Flag.

Draw Priority `drawpriority` - Determines the order in which the Components are drawn. Smaller values get drawn after (on top of) larger values.

Wireframe Color `wcolor` - Use the R, G, and B fields to set the Component's color when displayed in wireframe shading mode.

## Parameters - Common Page

The Common parameter page sets the component's node viewer, clone relationships, Parent Shortcut, and Global OP Shortcut.

Parent Shortcut `parentshortcut` - Specifies a name you can use anywhere inside the component as the path to that component. See Parent Shortcut.

Global OP Shortcut `opshortcut` - Specifies a name you can use anywhere at all as the path to that component. See Global OP Shortcut.

Node View - Determines what is displayed in the node viewer, also known as the Node Viewer. Some options will not be available depending on the Component type (Object Component, Panel Component, Misc.)

• Geometry Viewer - Shows a 3D geometry viewer displaying the geometry inside the component. This option is only available for Object components.
• Control Panel - Displays the Control Panel, only available for Panel Components.
• Operator Viewer - Displays the node viewer from any operator specified in the Operator Viewer parameter below.

Operator Viewer `opviewer` - Select which operator's node viewer to use when the Node View parameter is set to Operator Viewer.

Enable Cloning `enablecloning` - Control if the OP should be actively cloned.

Clone Master `clone` - Path to a component used as the Master Clone. If the component specified as Master exists, then this component becomes a clone.

Load On Demand `loadondemand` - Loads the component into memory only when required. Good to use for components that are not always used in the project.

External .tox `externaltox` - Path to a `.tox` file on disk which will source the component's content upon start of a `.toe`. This allows for components to contain networks that can be updated independently of the `.toe` file. Paths used to locate `.tox` files should not contain expressions or root variables. Built-in and Environment variables (like `\$MYDOCUMENTS`, `\$DESKTOP` and `\$HOME`) are accepted. If the `.tox` file can not be found, whatever the `.toe` file was saved with will be loaded.

Reload .tox on Start `reloadtoxonstart` - When on (default), the external .tox file will be loaded when the .toe starts and the contents of the COMP will match that of the external .tox. This can be turned off to avoid loading from the referenced external .tox on startup if desired (the contents of the COMP are instead loaded from the .toe file). Useful if you wish to have a COMP reference an external .tox but not always load from it unless you specifically push the Re-Init Network parameter button.

Save Backup of External `savebackup` - When this checkbox is enabled, a backup copy of the component specified by the External `.tox` parameter is saved in the `.toe` file. This backup copy will be used if the External `.tox` can not be found. This may happen if the `.tox` was renamed, deleted, or the `.toe` file is running on another computer that is missing component media.

Sub-Component to Load `subcompname` - When loading from an External `.tox` file, this option allows you to reach into the `.tox` and pull out a COMP and make that the top-level COMP, ignoring everything else in the file (except for the contents of that COMP). For example if a `.tox` file named `project1.tox` contains `project1/geo1`, putting `geo1` as the Sub-Component to Load, will result in `geo1` being loaded in place of the current COMP. If this parameter is blank, it just loads the `.tox` file normally using the top level COMP in the file.

Re-Init Network `reinitnet` - This button will re-load from the external `.tox` file (if present), followed by re-initializing itself from its master, if it's a clone.