Custom Effect

Work in progress, the feature is not part of main branch!

You can download binaries with the test version of the feature in the release page of the openmobu repository

Concept of custom effect video

Custom effect gives you a way to make a new effect for the post processing system. The effect is based on fragment glsl shaders.

There is a big collection of shader examples at shadertoy resource

Below you can find a topic on how to adapt a shadertoy shader

New assets

• Effect Shader

• pre-defined effect shaders: Blur Shader and Mix Shader

Examples

You can find example scenes in the openmobu repositiory / MB_Scenes folder

original scene without post processing

fxaa effect

god rays effect

sketchy effect

sketchy effect 2

System Uniforms

name	declaration	description
inputSampler	uniform sampler2D inputSampler;	this is an input image from the processing chain. The image of all previous applied effects during frame render.
iChannel0		same as inputSampler
depthSampler	uniform sampler2D depthSampler;	this is a scene depth texture sampler, based on scene raw depth information
linearDepthSampler	uniform sampler2D linearDepthSampler;	a depth texture converted into a linear space https://web.archive.org/web/20130416194336/http://olivers.posterous.com/linear-depth-in-glsl-for-real
maskSampler	uniform sampler2D maskSampler;	binded mask texture for a shader processing. mask is defined per post processing object
normalSampler	uniform sampler2D normalSampler;	not supported yet
useMasking	uniform float useMasking;	float uniform [0; 1] to define if the mask have to be used
upperClip	uniform float upperClip;	this is an upper clip image level. defined in a texture coord space to skip processing
lowerClip	uniform float lowerClip;	this is a lower clip image level. defined in a texture coord space to skip processing
gResolution	uniform vec2 gResolution;	vec2 that contains processing absolute resolution, like 1920x1080
iResolution		same as gResolution
uInvResolution	uniform vec2 uInvResolution;	1.0 / iResolution.xy
texelSize	uniform vec2 texelSize;	vec2 of a texel size, computed as 1/resolution
iTime	uniform float iTime;	compatible with shadertoy, float, shader playback time (in seconds)
iDate	uniform vec4 iDate;	compatible with shadertoy, vec4, (year, month, day, time in seconds)
cameraPosition	uniform vec3 cameraPosition;	current camera position in world space
modelView	uniform mat4 modelView;	current camera modelview matrix
projection	uniform mat4 projection;	current camera projection matrix
modelViewProj	uniform mat4 modelViewProj;	current camera modelview-projection matrix
invModelViewProj
prevModelViewProj		modelview-projection matrix from a previous frame (used in motion blur)
zNear		camera near plane
zFar		camera far plane

Uniform Special Postfix

During compilation the shader effect is going to pick the system uniforms and user uniforms. For user uniforms is going to make object properties, so that user could customize the input values for the shader render.

There is a way to customize the ui elements based on a given special postfix to a uniform name

Uniform type	Postfix	Description
float	_slider	make a UI with clamped range [0; 100] and convert it into [0; 1] as output
float	_flag	make a checkbox and cast the on/off flag to a float [0; 1]
vec2	_wstoss	make a vector3 ui element and convert value from a world space into vec2 uniform in screen space
vec3	_color	make a color RGB picker and output as vec3
vec4	_color	make a color RGBA picker and output as vec4

Shadertoy shaders and adaptation for a custom effect

ShaderToy compatibility mode

Turn on the correspondent flag in your user effect shader object to make a header and footer to support a code from shader toy effect.

Steps to manually adjust your shader

First of all, we have to add a header information about shader version and input, output values. In our case the input value is vec2 TexCoord which represents a processed texel position in uv space [0; 1] and output is vec4 FragColor which is our computed texel color.

#version 140

in vec2 TexCoord;
out vec4 FragColor;

The main entry function have to be renamed from

void mainImage( out vec4 fragColor, in vec2 fragCoord )

into

void main(void)

The output variable to store a texel color is called FragColor with capital letter while shadertoy shader has fragColor with a lower case.

The input TexCoord is in uv space, while shadertoy shader operates with fragCoord in image space. In order to convert from uv space into image space, we have to multiply our tex coord by image resolution.

vec2 fragCoord = TexCoord * iResolution.xy;

where iResolution is system uniform that have to be defined in the top of the shader

uniform vec2 iResolution;

For shaders that require buffers, you need to create each buffer as a separate GLSL fragment shader and use them to compose an effect shader. Then, connect these shaders together in the execution chain. When you have a sampler2D uniform, it will be exposed as a list object property in MotionBuilder, allowing another shader or texture to be used to compute that input.