Wizt::SplatRenderObject Class Reference
[The Fish Eye Retina - Fiber Bundle to OpenGL Gateway via Vish API]

Base class for render object that draw a splat for each vertex of a Grid object. More...

#include <SplatRenderObject.hpp>

Inheritance diagram for Wizt::SplatRenderObject:

List of all members.

Classes

struct Renderer
A Vertex Buffer Render object for making splats. More...

Public Member Functions

SplatRenderObject (const string &name, int p, const RefPtr< VCreationPreferences > &VP, double SizeScale=5.0)
Constructor.
~SplatRenderObject ()
Destructor.
virtual string vertex_shader (VRenderContext &Context) const
Default vertex shader code that sets point size and transparency attenuation for very small points.
virtual string fragment_shader (VRenderContext &Context) const
Default fragment shader code, must derive from to get this 2D texture.
virtual void setShaderVariables (VRenderContext &Context, const RefPtr< Program > &ShaderProgram) const
Virtual function to set variables in the shader program, such as parameters from the Vish inputs.
RefPtr< VBO::Renderer > createRenderer (VRenderContext &Context, const RefPtr< MemBase > &FieldCoordinates, const RefPtr< FragmentSelector > &FS) const
Render function: create a renderer object.
override void setRendererParameters (VRenderContext &Context, const RefPtr< VBO::Renderer > &theRenderer, const RefPtr< CreativeArrayBase > &VertexCoordinates) const
Update a renderer object, in case the fragment selector is newer.
override bool request (VRequest &R, double precision)
override void render (VRenderContext &Context) const

Static Public Member Functions

static const char * setPointAttenuation ()
A vertex shader fragment defining a function that will set the gl_PointSize to some value suitable for splats that get smaller in distance.
static string createChildname (const string &parent_name)
Predefined way to set the name of a render object.

Public Attributes

TypedSlot< double > sizeFactor
The exponential scaling factor for the size of the splats.
TypedSlot< double > AnimationSpeed
Animation control.
TypedSlot< double > MaxSize
The maximal pixel diameter value.
TypedSlot< VEnum > renderMode

Detailed Description

Base class for render object that draw a splat for each vertex of a Grid object.

Subclasses may define the way how such splats are drawn, and parameterize them based on the given input fields.

Member Function Documentation

string Wizt::SplatRenderObject::fragment_shader ( VRenderContext & Context ) const [virtual]

Default fragment shader code, must derive from to get this 2D texture.

           uniform sampler2D PSFTexture;
           void main (void)
           {
           vec4 psf  = texture2D( PSFTexture, gl_TexCoord[0].st);
           gl_FragColor = psf*gl_Color;
           }

When creating the shader program, do

And in function setRendererParameters() call

const char * Wizt::SplatRenderObject::setPointAttenuation ( ) [static]

A vertex shader fragment defining a function that will set the gl_PointSize to some value suitable for splats that get smaller in distance.

Also it will let them fade out once too small. Add this code to the prefix of some vertex shader.

void main(void)
{
        gl_FrontColor.rgb = vec3(0.5,0.5,0.3);
        gl_Position = ftransform();

        gl_FrontColor.a = setPointAttenuation();
 }

This function will return the following GLGS code:

uniform float size;

float setPointAttenuation()
{
vec4 eyeCoord = gl_ModelViewMatrix * gl_Vertex;
float dist = distance(eyeCoord, vec4(0.0, 0.0, 0.0, 1.0));
float att = 1.0/dist;
float diameter = clamp(size* att, 0.0,100.0);

float   fadeThreshold = 1.0;
float   fadePower = 1.5;
        gl_PointSize = max(diameter, fadeThreshold);
float   fade = min(diameter, fadeThreshold)/fadeThreshold;
        return pow(fade, fadePower)
}

void Wizt::SplatRenderObject::setRendererParameters	(	VRenderContext &	Context,
		const RefPtr< VBO::Renderer > &	theRenderer,
		const RefPtr< CreativeArrayBase > &	VertexCoordinates
	)			const `[virtual]`

Update a renderer object, in case the fragment selector is newer.

Render function: set parameters in the renderer that don't need re-creation of the VBO

Reimplemented from Wizt::FragmentPainter.

References Wizt::VRenderContext::isCancelled().

void Wizt::SplatRenderObject::setShaderVariables	(	VRenderContext &	Context,
		const RefPtr< Program > &	ShaderProgram
	)			const `[virtual]`

Virtual function to set variables in the shader program, such as parameters from the Vish inputs.

Typical code might just assign slots to uniform variables:

           struct       MySplatter : SplatRenderObject
           {
                TypedSlot<double>   Value;

                MySplatter(...)
                : SplatRenderObject(...)
                , Value(this, "value", 0.23)
                {}

                override string vertex_shader(VRenderContext&Context) const
                {
                        return "uniform float value; ....";
                }

                override void setShaderVariables(VRenderContext&Context, const RefPtr<Program>&ShaderProgram) const
                {
                        Value << Context > ShaderProgram;
                }
           };

Note that the name of the slot must be equal to the name of the uniform variable in the shader program for this to work. If the names don't match, then an OpenGL error exception will be thrown.

string Wizt::SplatRenderObject::vertex_shader ( VRenderContext & Context ) const [virtual]

Default vertex shader code that sets point size and transparency attenuation for very small points.

To make use of this functionality, the code returned by setPointAttenuation() must be included in the code provided by an implementation of this function, and the setPointAttenuation() function needs to be called in the vertex shader. Its return value is a transparency factor that is supposed to be used to attenuate the alpha value of the given colors. The default main function as returned by the vertex_shader function is

void main(void)
{
        gl_FrontColor.rgb = vec3(0.5,0.5,0.3);
        gl_Position = ftransform();
        gl_FrontColor.a = setPointAttenuation();
}