---
title: Defold materials manual
brief: This manual explains how to work with materials, shader constants and samplers.
---
# Materials
Materials are used to express how a graphical component (a sprite, tilemap, font, GUI node, model etc) should be rendered.
A material holds _tags_, information that is used in the rendering pipeline to select objects to be rendered. It also holds references to _shader programs_ that are compiled through the available graphics driver and uploaded to the graphics hardware and run when the component is rendered each frame.
* For more information on the render pipeline, see the [Render documentation](/manuals/render).
* For an in depth explanation of shader programs, see the [Shader documentation](/manuals/shader).
## Creating a material
To create a material, right click a target folder in the *Assets* browser and select New... ▸ Material. (You can also select File ▸ New... from the menu, and then select Material). Name the new material file and press Ok.
{srcset="images/materials/material_file@2x.png 2x"}
The new material will open in the *Material Editor*.
{srcset="images/materials/material@2x.png 2x"}
The material file contains the following information:
Name
: The identity of the material. This name is used to list the material in the *Render* resource to include it in the build. The name is also used in the render API function `render.enable_material()`. The name should be unique.
Vertex Program
: The vertex shader program file (*.vp*) to use when rendering with the material. The vertex shader program is run on the GPU for each of a component's primitive vertices. It computes the screen position of each vertex and also optionally output "varying" variables that are interpolated and input to the fragment program.
Fragment Program
: The fragment shader program file (*.fp*) to use when rendering with the material. The program runs on the GPU for each of a primitive's fragments (pixels) and its purpose is to decide the color of each fragment. This is usually done by texture lookups and calculations based on input variables (varying variables or constants).
Vertex Constants
: Uniforms that will be passed to the vertex shader program. See below for a list of available constants.
Fragment Constants
: Uniforms that will be passed to the fragment shader program. See below for a list of available constants.
Samplers
: You can optionally configure specific samplers in the materials file. Add a sampler, name it according to the name used in the shader program and set the wrap and filter settings to your liking.
Tags
: The tags associated with the material. Tags are represented in the engine as a _bitmask_ that is used by [`render.predicate()`](/ref/render#render.predicate) to collect components that should be drawn together. See the [Render documentation](/manuals/render) on how to do that. The maximum number of tags you can use in a project is 32.
## Vertex and fragment constants
Shader constants, or "uniforms" are values that are passed from the engine to vertex and fragment shader programs. To use a constant you define it in the material file as either a *Vertex Constant* property or a *Fragment Constant* property. Corresponding `uniform` variables need to be defined in the shader program. The following constants can be set in a material:
CONSTANT_TYPE_WORLD
: The world matrix. Use to transform vertices into world space. For some component types, the vertices are already in world space when they arrive to the vertex program (due to batching). In those cases multiplying with the world matrix in the shader will yield the wrong results.
CONSTANT_TYPE_VIEW
: The view matrix. Use to transform vertices to view (camera) space.
CONSTANT_TYPE_PROJECTION
: The projection matrix. Use to transform vertices to screen space.
CONSTANT_TYPE_VIEWPROJ
: A matrix with the view and projection matrices already multiplied.
CONSTANT_TYPE_WORLDVIEW
: A matrix with the world and view projection matrices already multiplied.
CONSTANT_TYPE_NORMAL
: A matrix to compute normal orientation. The world transform might include non-uniform scaling, which breaks the orthogonality of the combined world-view transform. The normal matrix is used to avoid issues with the direction when transforming normals. (The normal matrix is the transpose inverse of the world-view matrix).
CONSTANT_TYPE_USER
: A vector4 constant that you can use for any custom data you want to pass into your shader programs. You can set the initial value of the constant in the constant definition, but it is mutable through the functions [go.set()](/ref/stable/go/#go.set) / [go.animate()](/ref/stable/go/#go.animate). You can also retrieve the value with [go.get()](/ref/stable/go/#go.get). Changing a material constant of a single component instance [breaks render batching and will result in additional draw calls](/manuals/render/#draw-calls-and-batching).
Example:
```lua
go.set("#sprite", "tint", vmath.vector4(1,0,0,1))
go.animate("#sprite", "tint", go.PLAYBACK_LOOP_PINGPONG, vmath.vector4(1,0,0,1), go.EASING_LINEAR, 2)
```
## Samplers
Samplers are used to sample the color information from a texture (a tile source or atlas). The color information can then be used for calculations in the shader program.
Sprite, tilemap, GUI and particle effect components automatically gets a `sampler2D` set. The first declared `sampler2D` in the shader program is automatically bound to the image referenced in the graphics component. Therefore there is currently no need to specify any samplers in the materials file for those components. Furthermore, those component types currently only support a single texture. (If you need multiple textures in a shader, you can use [`render.enable_texture()`](/ref/render/#render.enable_texture) and set texture samplers manually from your render script.)
{srcset="images/materials/sprite_sampler@2x.png 2x"}
```glsl
-- mysprite.fp
varying mediump vec2 var_texcoord0;
uniform lowp sampler2D MY_SAMPLER;
void main()
{
gl_FragColor = texture2D(MY_SAMPLER, var_texcoord0.xy);
}
```
You can specify a component's sampler settings by adding the sampler by name in the materials file. If you don't set up your sampler in the materials file, the global *graphics* project settings are used.
{srcset="images/materials/my_sampler@2x.png 2x"}
For model components, you need to specify your samplers in the material file with the settings you want. The editor will then allow you to set textures for any model component that use the material:
{srcset="images/materials/model_samplers@2x.png 2x"}
```glsl
-- mymodel.fp
varying mediump vec2 var_texcoord0;
uniform lowp sampler2D TEXTURE_1;
uniform lowp sampler2D TEXTURE_2;
void main()
{
lowp vec4 color1 = texture2D(TEXTURE_1, var_texcoord0.xy);
lowp vec4 color2 = texture2D(TEXTURE_2, var_texcoord0.xy);
gl_FragColor = color1 * color2;
}
```
{srcset="images/materials/model@2x.png 2x"}
## Sampler settings
Name
: The name of the sampler. This name should match the `sampler2D` declared in the fragment shader.
Wrap U/W
: The wrap mode for the U and V axes:
- `WRAP_MODE_REPEAT` will repeat texture data outside the range [0,1].
- `WRAP_MODE_MIRRORED_REPEAT` will repeat texture data outside the range [0,1] but every second repetition is mirrored.
- `WRAP_MODE_CLAMP_TO_EDGE` will set texture data for values greater than 1.0 to 1.0, and any values less than 0.0 is set to 0.0---i.e. the edge pixels will be repeated to the edge.
Filter Min/Mag
: The filtering for magnification and minification. Nearest filtering requires less computation than linear interpolation, but can result in aliasing artifacts. Linear interpolation often provides smoother results:
- `FILTER_MODE_NEAREST` uses the texel with coordinates nearest the center of the pixel.
- `FILTER_MODE_LINEAR` sets a weighted linear average of the 2x2 array of texels that lie nearest to the center of the pixel.
- `FILTER_MODE_NEAREST_MIPMAP_NEAREST` chooses the nearest texel value within an individual mipmap.
- `FILTER_MODE_NEAREST_MIPMAP_LINEAR` selects the nearest texel in the two nearest best choices of mipmaps and then interpolates linearly between these two values.
- `FILTER_MODE_LINEAR_MIPMAP_NEAREST` interpolates linearly within an individual mipmap.
- `FILTER_MODE_LINEAR_MIPMAP_LINEAR` uses linear interpolation to compute the value in each of two maps and then interpolates linearly between these two values.
## Constants buffers
When the rendering pipeline draws, it pulls constant values from a default system constants buffer. You can create a custom constants buffer to override the default constants and instead set shader program uniforms programmatically in the render script:
```lua
self.constants = render.constant_buffer() -- <1>
self.constants.tint = vmath.vector4(1, 0, 0, 1) -- <2>
...
render.draw(self.my_pred, {constants = self.constants}) -- <3>
```
1. Create a new constants buffer
2. Set the `tint` constant to bright red
3. Draw the predicate using our custom constants
Note that the buffer's constant elements are referenced like an ordinary Lua table, but you can't iterate over the buffer with `pairs()` or `ipairs()`.