Amazon Sumerian Material Component - Amazon Sumerian

Amazon Sumerian Material Component

When you add a 3D model to your scene, it has at least three components. The Transform component defines the positioning of the model in 3D space, the Geometry component defines the shape of the model, and the Material component defines its textures and rendering properties. 

Amazon Sumerian currently supports two different shading models. The first is the Classic Model, which uses the dynamic lights and the Classic shader in the Material component. The second is Physically Based Rendering which uses PBR shaders and an Environment Light to create a more photo-real appearance. 

Classic Shader

The Classic shader in the Material component is one type of  material supported in Sumerian. It is good for achieving a stylized look and requires less memory intensive material than a  PBR shader. 

Properties

Color (Diffuse) – The base color of the surface. 

  • Color – The base diffuse color. This defines the base color of the object.  

  • Texture – The diffuse color from a texture. A texture is an image file that is placed on the object based the UV layout.

Normal – A type of bump map. Normal maps are a special kind of texture that you use to add surface detail such as bumps, grooves, and scratches to an object. These details catch the light as if they are represented by real geometry.  You set the normal map via the Texture input, and you can alter its magnitude by setting the Strength value.

Specular – Specular effects are the direct reflections of light sources in your scene. These typically show up as bright highlights or shininess on the surface of object, though specular highlights can be subtle or diffuse. You can set the base specularity Color, use a Texture, and set the Shininess value.

Emissive – The self-illumination color of an object, which can be described as the amount of “glow” an entity emits. You can set the emissive color by using the Color input and/or by using a Texture.

Ambient – The color and value of an object without considering light information. This property drives additional light into the material.

  • Color - The base ambient color.

  • Texture - Ambient map that identifies areas on a mesh that are exposed or hidden from ambient lighting.

Opacity – Defines the transparency/opaqueness of an object. You can use Strength to input a value between 0 and 1, where 0 represents completely transparent and 1.0 represents fully opaque. 

  • Threshold – Used to indicate when a surface is completely transparent and can be discarded from rendering. 

  • Dual Transparency – Renders both front and back surfaces of the material.

Reflectivity – Defines how much and what is reflected by the material.

  • Texture – The image that will be reflected off the material based the object’s UV information.

  • Environment – Map that creates a spherical projection. This is image that the material will be visibly reflected off the surface of the object. If not selected, the current Skybox is used. 

  • Amount – The intensity of the object’s reflection. 

  • Fresnel – The falloff of the glancing angle. A value greater than 0 results in less reflection, depending on the normal direction. 

Refractivity – Takes in a texture or value that simulates the surface's index of refraction. This is useful for things like glass and water, which refract light that passes through them. The environment texture is used for the refraction. 

  • Amount – How much refraction to blend with the current color.

  • Refraction – Ratio of the refractive indices involved in the refraction.

Blending – Blending mode to use for the material. It is an advanced color and reflectivity property for producing alpha layers, color subtraction, inverse control, negative values, etc.

  • NoBlending

  • TransparencyBlending

  • CustomBlending

  • AdditiveBlending

  • SubtractiveBlending

  • MultiplyBlending

Culling – Controls which side of the object is visible. In general, Cull Face Back defines that the outside of the object is visible, while Front defines that the inside of the object is visible. CW and CCW define which side of the inside is visible. 

Depth – Enables rendering to the depth buffer. When enabled, Sumerian will show an object if it’s not blocked by another object. Conversely, it won’t render an object if it’s blocked by another object. By turning this property off, the engine will render and show all objects regardless of their placement in a scene. This property could be used for transparent objects. 

Shading - Dictates the visibility and use of the polygons within an object’s mesh. Flat turns on flat shading for the mesh, meaning the polygons are enunciated and shadows are dependent on the edges of the polygons.

  • Flat – Turns on flat shading for the mesh.

  • Wireframe – Renders the mesh in wireframe mode.

  • Wrap factor – The light wrap factor.

  • Wrap amount – The light wrap amount.

To learn more, visit the Material Deep Dive tutorial.

Physically Based Rendering (PBR) and Environment Lighting (HDRI)

Physically based rendering (PBR) is the method of shading and rendering that more accurately represents how light interacts with surfaces. This means that metal and dielectric (non-metal) objects will render closer to their real word counterparts. 

A high dynamic range image, or HDRI, is used to reproduce a greater dynamic range of luminosity. The image format is .hdr. In the section below we will take a look at how to setup the Environment Light properties under the global scene settings. When using the Environment Lighting  (HDR) component, a scene will be lit with luminosity information from an image (the HDRI) instead of, or in combination with, the existing dynamic lights in Sumerian. The reflections are also based on the HDRI making the scene more physically accurate. 

Environment Light (HDR)

To setup the Environment Light in Sumerian you will first need to get an HDRI image. Once you have your scene created and your object imported you can access the HDRI assets by pressing Import Assets at the top of the Editor. Search for “HDRI” and look for an HDRI you want to use to light the scene. After you have imported your HDRI look for the image in the Assets panel. Make sure you're at the scene root by clicking the top node in the Entities panel (the top level entity that carries the name you gave to your scene). Click and drag the HDRI from the Assets panel into the Environment Lighting (HDR) property on the right hand side of the editor. 

Alternately you can use the Default Lighting: PBR template when you create a new scene and use the HDRI already setup in that scene. 

Keep in mind that .hdr images are much larger than a normal .jpg image and you may need to reduce the size of the image in order to have a performant web Sumerian scene. It is recommended to use a 2k or 4k HDRI to light your scene. Reducing the size of your HDRI (.hdr) will lower the quality of your reflections but should increase performance on devices with reduced capacity, such as mobile. The quality reduction is usually mitigated by the smaller screen format but the scene should be tuned to create the best results. 

Note: The .hdr asset type can only be applied to the Environment Lighting HDR property and cannot currently be used as a texture for anything else in Sumerian. Conversely, image format types that are of any other type than .hdr cannot be used in the Environment Lighting HDR property. 

Setting up the light

Once you have imported your HDRI, click the scene level entity in the Entities  panel to access the Environment Lighting (HDR) options. The scene below has an HDRI and it can be seen in the asset panel in the lower left of the editor. It is marked with the new light bulb icon to denote it as an HDRI texture vs a regular texture image. 

Note: Currently the sphere is completely black as there are no lights in use in the scene. 

Once you have accessed the Environment Lighting (HDR) property you can either:

  • Drag your HDRI image onto the HDR drop input

  • Click the Browse button and load an HDRI from a file on your local computer

This will load the HDRI into the scene. Below we can see the HDRI has been loaded into the scene and the sphere is now lit by the HDRI. 

If we adjust the Brightness slider in the Environment Lighting (HDR) property we can see the results of how the lighting is changed on the sphere. 

The HDRI  can be seen in the lighting and reflections of our sphere’s material. We can use this image as the Skybox texture by choosing Set as Skybox.

To discontinue the use of either the Skybox or HDR texture  click Remove Textures in either the Skybox or Environment Lighting (HDR) property and it will remove the corresponding texture. 

Note that it is possible to drop a different texture into the Skybox texture input other than the one used for your HDR light. However, the reflections of the material will still be based on the HDRI and won't match the texture used for the Skybox

The Skybox and Environment Lighting (HDR) components can each be rotated 360 degrees through the Rotation(Y) property. Rotating the HDRI will spin the image around the center of the scene. This allow one to control which direction the light is coming from to better refine the lighting in the scene. If you want the Skybox rotation to be synced with the Environment Lighting (HDR) rotation then press the Sync Skybox checkbox. This will ensure that the reflections in the materials match the lighting. 

PBR Materials

Now that your light is setup we can now look at how PBR shaders work. 

Sumerian supports two different PBR materials, Metalness ( PBR metal/roughness) and Specular (PBR specular/glossy). These two materials use different equations for calculating how the specular reflections are displayed on the material but they also share several properties. These shared properties are listed below in the two different PBR material descriptions. 

In choosing which PBR material to use keep the following in mind:

  • Using the PBR Specular material will give more control over the reflectivity of non-metal materials providing a full color input for reflective (specular) color. The PBR Specular material may be preferred by artists with heavy experience in traditional shaders because the maps and methods used are more similar. 

  • The PBR Metalness material simplifies metals vs. non-metals (dielectric) which can make it easier to author content.  However, the material transitions (places where the material changes from metal to dielectric) can sometimes leave a white line artifact. It's best to try to break up your metal and dielectric objects into different materials if this occurs. 

  • The PBR Metalness material uses the Base Color property(the color of the object before specular reflections are calculated), the Metalness property (how and where the material is metal), and the Roughness property ( the shape of the specular reflection ), and the Specular F0 property (to modify the reflectivity of non-metal objects). 

The PBR Metalness Material

Base Color  - Similar to the Diffuse. It is the main color that will appear on the object. It can be modified in two ways. 

  • Color - Color picker. If no texture is applied will be the color of the object.

  • Texture -  A texture map can be uploaded and displayed on the object for the Base Color. The Color is multiplied over the texture. This means that the texture can be “tinted” a different color if the Color value is not a grey scale value. The  texture can also contain transparency through the use of a .png file. See the section below on Opacity to see how to use this property. 

Base Color Only

Base Color Using the Texture Slot

Base Color using both the Color Swatch and Texture. Notice how the texture is now tinted. The color black will not tint as the color is multiplied over the texture. 

Metalness - Used to determine which parts of the object are metal and which are not. 

  • Texture - This texture should be grey scale map (a texture without color information) which creates a value where the metal parts are white and the non-metal or dialectic parts are black. Values of grey can be used but usually this map will be only black or white. It can also be a combined Metallic_roughness_map with metallic in B channel.

  • Strength - This is a multiplier of the texture. The value should be set to 1 if a texture is applied. If the value is set to less than 1 then the textures values are reduced and the object will appear progressively less metal as the strength approaches 0. If no texture is used then a value of 0 is non-metal and a value of 1 is full metal. 

Metalness Value of 0 means the material is non-metal or dielectric. 

Metalness Value of 1 means the material is metal.

As the Roughness Strength is increases you will see the specular highlights soften and the object will appear less glossy and rougher. 

If we want to achieve a colored metal such as gold or copper, the Base Color can be adjusted to tint the reflection of a metal object. 

If we add a texture to the texture slot for Metalness then we can see how the white parts of the texture appear as metal (value of 1) and the black parts of the texture appear as non-metal (value of 0). Notice how the metal parts of the texture are highly reflective and deep in color despite the white Base Color of the material. The metallic areas of the object are still using the white Base Color. 

Roughness - Modifies how the object reflects light. If the value is high the reflection is blurred across the object and the object will appear rough in nature. If the value is low the object will appear smoother and the refection will be clear. 

  • Texture - This is a grey scale map where black is a low roughness value (object will appear smooth and reflective) and white is a high roughness value (the object will appear rough with blurred reflections).  It also can be a combined metallic_roughness_map which is single texture that contains information for both Metalness and Roughness in one texture instead of two with Roughness in green channel and Metalness in the blue channel. 

  • Strength - This is a multiplier of the texture. The value of the strength should be set to 1 if a texture is applied. If the value is set to less than 1 then the textures values are reduced and the object will appear progressively smoother as the Strength approaches 0.

As the Roughness value is increased you can see the object change from glossy to rough. Keep note of the Strength value for the Roughness property and how it affects the specular highlight. 

If we place a texture into the texture slot of the Roughness property we can see how the specular highlight is affected. Note how the specular highlight is tight or glossy where the roughness value is black (value of 0) and the highlight is broad to the point where it's almost not visible in the white sections of the texture (value of 1), where the material has been tinted red to better show the highlight. 

Specular F0 - This is a scalar value that modifies the reflectivity of the object if it is non-metallic (dielectric). A value of 1 is fully reflective and a value of 0 is non-reflective. 

  • Texture -  This is a grey scale texture that can be used to modify the reflectivity of the object. It will be a multiplicative value where white creates full reflectivity and black removes reflectivity. 

  • Strength - This is a multiplier of the texture (if used). If no texture is used then the Strength value will set the reflectivity of the whole object. A value of 0 is no reflectivity with increasing reflectivity up to a value of 1 which is full reflectivity. 

In the following two images we can see the effect, or lack thereof, on a metallic material. This material has the Metalness value set to 1. We can see that the Specular F0 Reflectivity value has no effect on a metallic material. 

The Specular F0 controls the reflectivity of non-metallic material. The material Base Color has been turned black and the specular reflections are clearly visible. Note how the highlight intensity changes from non-existent, when the reflectivity is set to 0, to visible when the reflectivity is set to 1. 

You can also place a texture into the texture slot of the Specular F0 to control the reflectivity of an object. Note how the black sections (value of 0) of the texture are non-reflective and the white sections (value of 1) are highly reflective. 

The PBR Specular Material

The PBR Specular material is different from the PBR Metalness material. There are three main properties to use in the PBR Specular material: Diffuse (similar to Base Color), Specular (controls the value of the specular reflectivity as well as its color), and Glossiness (controls how tight or broad the specular reflections appear in the material).  You may think of the Glossiness property as being the inverse of Roughness in the PBR Metalness material as the texture maps are the inverse of each other. 

In Specular there is no Metalness property. This means that in order to achieve a metal looking material the Diffuse Color will be set to a dark color (usually black), and the Specular color will be used to determine the tint of the specular reflections of the metal. The Glossiness value will most likely be high in order to create a highly reflective metal. It can also be lowered to achieve a more tarnished or dusty metal. 

Diffuse - Similar to the Base Color of the object. It is the main color that will appear on the object. The diffuse color can be modified in two ways. 

  • Color - This is a color picker and if no texture is applied will be the color of the object.

  • Texture -  A texture map can be uploaded and displayed on the object for the Diffuse. The Color is multiplied over the texture. This means that the texture can be tinted a different color if the Color value is not a grey scale value. The  texture can also contain transparency through the use of a .png file. Make sure to enable Opacity if a texture with transparency is used. This will ensure that the map with transparency displays correctly. 

In this image the Diffuse Color has been changed to red. 

Checkered texture with no Diffuse Color. 

Diffuse Color Red and Diffuse texture set to a checkered pattern. You can see that the white areas of the texture have been tinted by the color swatch. 

Specular - Controls the amount of reflection on an object. 

  • Color - Specular reflections can be tinted through the color picker. The Color property will also multiply over the texture placed into the specular texture property. 

  • Texture - A texture map can be uploaded to apply color to the specular of an object. Lighter color textures will make the object more reflective. Darker colors will make the object less reflective: Black is non-reflective and white is fully reflective. 

Here we can see the specular reflections change from  highly reflective to non-reflective as we change the Specular Color from white (value of 1) to black (value of 0). Please note that the shape of the specular reflections do not change. They remain sharp because that is controlled by the glossiness value which remains at 1 throughout this set of images. 

When using a texture in the Specular texture slot we can see the same result. The white parts of the texture are rendered with a high specular reflectivity and the black parts of the texture are rendered non-reflective. 

Specular values can also take color information. When the color swatch is used it will tint the texture. The white sections of the texture are now tinted red and the black parts of the texture remain non-reflective. 

Similarly, the texture itself can contain color information for the Specular. Here we can see that the colored texture is tinting the specular reflectivity of the material across the object. 

Glossiness - Modifies how the object reflects light. If the value is high then the reflection is sharpened across the object and the object will appear glossy or smooth in nature. If the value is low then object will appear more rough and the refection will be blurred. 

  • Texture - This is a grey scale map where black equals a low glossiness value (object will appear rough) and white has a high glossiness value (the object will appear smooth with sharp reflections). The Texture can also be a combined specular_glossiness_map, a single texture that contains information for both Glossiness and Specular in one texture instead of two, where Glossiness information is in the alpha channel and the Specular color information in the RBG channels. 

  • Strength - This is a multiplier of the texture. The value of the Strength should be set to 1 if a texture is applied. If the value is set to less than 1 then the textures values are reduced and the object will appear progressively rougher as the strength approaches 0.

As we move through these series of images please note how the shape of the specular reflections change. They will change from tight spots which make the material appear to be slick or glossy to very broad, which makes the material appear rougher. The specular value remains the same throughout these images so the material has the same brightness of reflections. Only the shape of the specular reflections are changed. 

Because Glossiness is a grey scale value the color information in textures has no effect. Only the brightness values (dark to light or black to white) of the texture will control the glossiness of the material. Here we can see that the white sections of the texture are rendered with a tight specular reflectivity and the dark sections of the texture are rendered with a broad or rough reflectivity. 

Shared Material Properties

The PBR Metalness and PBR Specular materials do have some shared properties.

Normal - A type of bump map. Normal maps are a special kind of texture used to add surface detail such as bumps, grooves, and scratches to a model. These details catch the light as if they are represented by real geometry. 

  • Texture - Place a normal map texture in this slot to modify the normal values of the object. 

  • Strength - This value modifies the magnitude of the texture map. A value of less than 1 decreases the influence of the texture as the strength approaches 0. A value of 0 is the same as not using a Normal texture map. The strength can also be raised over 1 to increase the influence of the normal texture. The strength will only take effect if the texture is applied. 

This image shows how the normal map has changed how the light and shadow are displayed on the object to simulate the existence of more geometry and give the sphere a bumped appearance.

Emissive - The self-illumination color of an object, which can be described as the amount of “glow” an entity emits. This does not mean that the object can be used to light other objects near it. This is only driving more light into the material of that object. 

  • Color - If no texture is used this color will set the overall color value for the self-illumination of the object. A color of black will remove self-illumination. If a texture is used then this color multiplies over the texture values to “tint” the texture.

  • Texture - A texture map can be uploaded to apply color to the Emissive of an object.The color in the texture will tint the Color value of the Emissive. Black will be non-emissive. 

Here we can see the material without the use of Emissive values because it is set to black. You can also uncheck Emissive  Color to ensure that the Emissive property is not in use. 

Here the Emissive color has been changed to red and now the object is self illuminating a red hue. 

If a texture is placed into the texture slot of the emissive property then the object will self-illuminate based on the color of the texture. Black creates a lack of Emissive effect. Anything else will cause the object to self-illuminate that particular color. 

Here we can see what happens when the color and texture options are used. The black sections of the texture still lack Emissive effect but the white sections of the texture are tinted by the color swatch. 

Ambient Occlusion - Determines how much ambient light will affect the object. It is used to approximate medium scale shadow details. 

  • Texture - The texture will be grey scale where black is no light contribution and white is full light contribution. A fully white texture will have no visible effect on the object when compared to the default settings. A full black texture will render darker object as no ambient light is being allow to light the object. The dark areas of the ambient occlusion texture will also reduce the amount of specular reflectivity. 

  • Strength -  The strength will modify the texture values where a strength value of 1 is using the full values of the texture and a value of 0 is the same as no texture. The strength will have no effect if no texture is applied. 

Here we can see the material with Ambient Occlusion turned off. When we apply the texture and move the strength to 1 we can see that the Ambient Occlusion is darkening the material where the texture is black and leaving the material the same where the texture is white. 

Cavity -  The cavity attribute is used to add shadow details, particularly in the small cracks or joints of an object. It operates much like an Ambient Occlusion texture.

  • Texture - The texture will be  grey scale where dark colors darken the material and white has no effect on the material. A fully white texture will have no visible effect on the object when compared to the default settings. The dark areas of the Cavity texture will also reduce the amount of specular reflectivity. 

  • Strength -  Modifies the texture values where a strength value of 1 is using the full values of the texture and a value of 0 is the same as no texture. The strength will have no effect if no texture is applied. 

Here we can see the checker texture applied to the Cavity attribute over a glossy red material. The black sections of the texture darken the material while the white sections have no effect.  You can see that the specular reflection is reduced by the black areas of the Cavity texture as well. 

Clear Coat -  This is used to simulate a thin reflective layer that sits on top of the surface of your material. This is useful for materials like car paint, wet surfaces or the gloss over polished woods. Conversely, if your object already has a glossy appearance and you want to rough it up a bit you can use the Clear Coat property with a wide specular falloff to add a layer of dust or grime. 

  • Color - Used to determine the tint of the Clear Coat over the object. 

  • Texture - The texture property is used as a grey scale texture map where white will be where Clear Coat is enabled and progressively reduces the strength of the Clear Coat until it's disabled at black. 

  • Intensity - The global value of how bright the Clear Coat specular will be. 

  • Thickness - Used to determine how thick the thin layer of polish over the material will be. Higher values will darken the material as less light is going to be let through the Clear Coat to the base color underneath. 

  • Reflectivity - Used to determine how reflective the surface of the Clear Coat is. Higher reflectivity will reflect more of the HDRI where as lower reflectivity will reflect less. 

  • Roughness -  A grey scale map where black creates a low roughness value (object will appear smooth and reflective) and white creates a high roughness value (the object will appear rough with blurred reflections).  

  • Strength -  Modifies the texture values where a strength value of 1 is using the full values of the texture and a value of 0 is the same as no texture. If no texture is applied a Strength value of 1 with render a rough specular reflection  and a value of 0 will render a glossy specular reflection. 

In this image the Clear Coat has been tinted red over a white sphere. The relatively low Thickness value allows the white material underneath the Clear Coat to partially show through. 

In this image a texture has been used to modulate the intensity of the Clear Coat. The black areas of the texture are nullifying the Clear Coat and letting the white material show through. the White areas of the texture are full Clear Coat and tinting red. 

Through the next set of images you can see how the Thickness property affects the Clear Coat. A low Thickness will show the material underneath the Clear Coat fairly well with a rim of Clear Coat visible at the glancing edges of the object. A mid value for Thickness will envelope the object. A high value for Thickness will reduce the light allowed through to the material under the Clear Coat and will start to darken the material. 

Raising the Reflectivity value will start to reflect more of the environment light. 

By modulating the Roughness of the Clear Coat with a texture we can see that the white areas of the texture give the Clear Coat a very broad and blurred specular reflection whereas the black areas of the texture make the Clear Coat glossy and reflective. 

Opacity - When enabled this modulates the transparency of an object.  This model of transparency is a simple form and will not accurately render more complicated features of transparency like translucency or refraction. The base color texture of the object may also contain opacity and transparency information to control the opacity of different parts of the object. This property is used in conjunction with the Blending properties. The default Blending option will be TransparencyBlending when Opacity is enabled and NoBlending when Opacity is disabled. 

Strength - If no texture is used a value of 1 will define the object as fully opaque. The opacity can be progressively lowered to a fully transparent object at a value of 0. If a texture is used it will multiply with the alpha channel in the texture applied to the Base Color or Diffuse property of the material. 

Threshold - This modifies the clipping of the transparency used in the base color map. A value of 0 will be no clipping and if there are semi transparent values in the texture they will appear correctly. If the Threshold value is increased from 0 to 1 then the opaque sections of the texture will be slowly eroded away until the texture is no longer used and the whole object is transparent when the Threshold reaches a value of 1

Dual Transparency -  When enabled this renders both sides of the object. 

Blending - This is used to set the blending mode when an object uses Opacity. The default setting is NoBlending when Opacity is disabled and TransparencyBlending when Opacity is first enabled. There are other Blending options available: 

  • NoBlending - The object will not use the opacity settings. 

  • TransparencyBlendng - The object will become transparent based on the opacity settings. There is no specialized blending that occurs on this setting. 

  • Custom Blending - This allows you to set the equation used for blending (add, subtract, reverse subtract), the source of the opacity information, and the target.

  • AdditiveBlending - This will take the opaque sections from the Opacity property and add their value over rest of the scene. This will create a brightening effect where the opaque sections exist. 

  • SubtractiveBlending - This will take the opaque sections from the Opacity property and subtract, or cut them out from the rest of the scene. This means that these sections will no longer be rendered through the camera in a Sumerian scene. 

  • MultiplyBlending - This will take the opaque sections from the Opacity property and multiply them over the rest of the scene. This will give a darkening effect where the opaque sections exist. 

Here a .png file has been applied to the Base Color texture slot. The image has a white Sumerian logo with a transparent background. The Opacity is checked to Enabled and the Blending mode was set to TransparencyBlending by default. This will be the setup most often used when using Opacity. 

If we lower the strength to 0.2 we can see how the opaque sections become more transparent. This is because the Strength slider acts as a global value for the Opacity property and will lower the opacity of the material evenly across the texture. 

If we go back to a high strength but also raise the Threshold value we can see that the opaque sections start to clip. The Threshold value is changing the border between the dark and light pixels of the texture. 

Dual Transparency. See how the material now renders the front and back faces of the object that are considered opaque as determined by the texture. The front faces rendering more white where the light is hitting them directly and the back faces are rendering darker where as they are shadowed by the front faces.

TransparencyBlending. This is the default blending mode and the most commonly used. 

MultiplyBlending. The transparent areas of the texture are now rendered white and the opaque areas are rendered black. This is because the opaque sections of the image are now multiplying over the rest of the scene whereas the transparent sections of the texture are not affecting the material. 

SubtractiveBlending. This results in the opaque parts of the texture subtracting themselves from the scene and the transparent parts of the texture staying transparent. This can be used in conjunction with the camera of your device so that the subtracted parts of the scene now render what the camera sees. 

AdditiveBlending. The opaque areas of the image are added to or lighten the scene whereas the transparent parts of the texture have no effect. 

If we use a texture with transparency in the Base Color but turn the Blending mode to NoBlending it will disable the Opacity and the material will no longer display the Opacity properties.