Shading Technique - Linear Depth Buffer - Revision history

Mikmacer: Change creation date to the good one

2008-09-07T02:03:06Z

Change creation date to the good one

Mikmacer at 01:47, 7 September 2008

2008-09-07T01:47:15Z

Mikmacer at 01:41, 7 September 2008

2008-09-07T01:41:58Z

Mikmacer at 01:37, 7 September 2008

2008-09-07T01:37:34Z

Mikmacer at 01:07, 7 September 2008

2008-09-07T01:07:17Z

Mikmacer: New page: {| border="0" | {{ContentBlock|width=800|color=white |content={{!!}} == Overview == '''Why using a custom Depth buffer?''' The default depth buffer generated by Horde3D is a non-linear...

2008-09-07T01:06:18Z

New page: {| border="0" | {{ContentBlock|width=800|color=white |content={{!!}} == Overview == '''Why using a custom Depth buffer?''' The default depth buffer generated by Horde3D is a non-linear...

New page

{| border="0"
| {{ContentBlock|width=800|color=white
|content={{!!}}

== Overview ==
'''Why using a custom Depth buffer?'''
The default depth buffer generated by Horde3D is a non-linear depth buffer and it is relative to the "Z Far" and the "Z Near" parameter. If you need to create screen space shader like "Depth of field" and "Screen Space Ambien Occlusion", a non-linear depth buffer could cause some problems since you will need to linearize the depth buffer each frames and any changement to the Z far and the Z near could affect any shaders using the Depth Buffer.

'''Requirements:'''<BR/>
- Basic knowledge of the Horde3D pipeline system.

== The shader ==
Can be put in the ATTRIBPASS or AMBIENT context to be used with the examples pipelines in the Horde3D SDK 1.0 beta.

'''Vertex shader:'''
Here, you can change the max distance constant. It determine the range and the precision of the depth buffer.

As you can see, there is two ways to calculate the depth of a vertex. The first one is to take the view space position of the vertex, and with this, you can take the Z value to get the depth. The second way is to create a vector from the view position to the vertex position, wich gave a slighter different result.

{{CppSourceCode|
description= Linear Depth - Vertex Shader|
code=
<source lang="cpp" line="1">
// Viewer position
uniform vec3 viewer;

// Depth vertex color
varying vec4 vVertexColor; // Black/near --> White/far

// Text coord
varying vec2 vTexCoords;
attribute vec2 texCoords0;

const float MAX_DISTANCE = 1000.0;

void main( void )
{
// Calculate world space position
vec4 pos = calcWorldPos( gl_Vertex );

// Calculate view space position
vec4 vsPos = calcViewPos( pos );

// Texture coordinate
vTexCoords = texCoords0;

// Calculate Depth
float distance = -vsPos.z / MAX_DISTANCE;//length(pos.xyz - viewer) / MAX_DISTANCE;

// Colorize the vertex with the distance
vVertexColor = vec4(distance);

gl_Position = gl_ModelViewProjectionMatrix * pos;
}
</source>}}

'''Fragment shader:'''

{{CppSourceCode|
description= Linear Depth - Fragment Shader|
code=
<source lang="cpp" line="1">
varying vec4 vVertexColor;
varying vec2 texCoords;

void main( void )
{
gl_FragColor = vVertexColor;
}
</source>}}

== How to use it ==
You must put the shader in EACH shaders that need to be affected by the depth buffer.

== Example Result ==

To be added.

== Pictures ==
To be added.

== To-Do List for this Article ==
- Add an exemple <br />
- Add a picture <br />
- Add an exemple pipeline <br />

}}
| valign="top" | {{Extension_Summary
|name = Technique - Linear Depth Buffer
|screenshot =
|description = Creating a custom linear depth buffer
|version = 1.0
|horde3dversion = 1.0 beta
|released = 2008-08-10
|author = [http://www.horde3d.org/forums/memberlist.php?mode=viewprofile&u=154 Mikmacer]|
}}
|}
[[category: Technique]]

@@ Line 83: / Line 83: @@
 With this, you only have to bind the VERTDEPTHBUF to any stage you want.
-I have called the depth pass DEPTH, but you can call it wathever you want. Don't forget to put the shader pass in EACH shaders that need to be affected by the depth buffer.
+I have called the depth pass DEPTH, but you can call it whatever you want. Don't forget to put the shader pass in EACH shaders that need to be affected by the depth buffer.
 == How to use it ==

@@ Line 105: / Line 105: @@
 |version = 1.0
 |horde3dversion = 1.0 beta
-|released = 2008-08-10
+|released = 2008-09-06
 |author = [http://www.horde3d.org/forums/memberlist.php?mode=viewprofile&u=154 Mikmacer]|
 }}
 |}
 [[category: Technique]]

@@ Line 11: / Line 11: @@
 == The shader ==
 '''Vertex shader:'''
@@ Line 94: / Line 93: @@
 == Pictures ==
-To be added.
+http://img255.imageshack.us/img255/7348/customdepthqi6.png
 == To-Do List for this Article ==
 - Add an exemple <br />
 }}

@@ Line 16: / Line 16: @@
 Here, you can change the max distance constant. It determine the range and the precision of the depth buffer.
-As you can see, there is two ways to calculate the depth of a vertex. The first one is to take the view space position of the vertex, and with this, you can take the Z value to get the depth. The second way is to create a vector from the view position to the vertex position, wich gave a slighter different result.
+As you can see, there is two ways to calculate the depth of a vertex. The first one is to take the view space position of the vertex, and with this, you can take the Z value to get the depth. The second way is to create a vector from the view position to the vertex position, wich gave a slightly different result.
 {{CppSourceCode|
@@ Line 27: / Line 27: @@
 // Depth vertex color
 varying vec4 vVertexColor; // Black/near --> White/far
-−
 const float MAX_DISTANCE = 1000.0;
@@ Line 65: / Line 61: @@
+}
 </source>}}
 == How to use it ==
-You must put the shader in EACH shaders that need to be affected by the depth buffer.
+You must put the shader pass in EACH shaders that need to be affected by the depth buffer.
 == Example Result ==

@@ Line 41: / Line 41: @@
 	// Calculate view space position
 	vec4 vsPos = calcViewPos( pos );
 	// Calculate Depth
@@ Line 62: / Line 59: @@
 <source lang="cpp" line="1">
 varying vec4 vVertexColor;
 void main( void )