Recent changes to Shader Functions

WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Wed, 24 Oct 2012 15:19:00 -0000

--- v12
+++ v13
@@ -3,7 +3,7 @@
 [image_shader] | vid, shader_id | | Change the active shader of the specified VID.
 [mesh_shader] | vid, shader_id, slot | | Associate a shader for the specified mesh slot.
 [build_shader] | vshdr, fshdr, label | shader_id | 
-[shader_uniform] | |shader_id, symbol, fmtstr, persist, ... | Define a value for the *symbol* slot uniform in the specifed shader, using a *fmtstr* to define how the variadic arguments at the end should map.
+[shader_uniform] | shader_id, symbol, fmtstr, persist, ... | | Define a value for the *symbol* slot uniform in the specifed shader, using a *fmtstr* to define how the variadic arguments at the end should map.
 
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WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Wed, 24 Oct 2012 15:18:43 -0000

--- v11
+++ v12
@@ -3,7 +3,7 @@
 [image_shader] | vid, shader_id | | Change the active shader of the specified VID.
 [mesh_shader] | vid, shader_id, slot | | Associate a shader for the specified mesh slot.
 [build_shader] | vshdr, fshdr, label | shader_id | 
-[shader_uniform] |shader_id, symbol, fmtstr, persist, ... | Define a value for the *symbol* slot uniform in the specifed shader, using a *fmtstr* to define how the variadic arguments at the end should map.
+[shader_uniform] | |shader_id, symbol, fmtstr, persist, ... | Define a value for the *symbol* slot uniform in the specifed shader, using a *fmtstr* to define how the variadic arguments at the end should map.
 
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WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Wed, 24 Oct 2012 15:18:27 -0000

--- v10
+++ v11
@@ -1,7 +1,9 @@
-Available Functions
----
-[image_shader] [mesh_shader] [build_shader] [shader_uniform]
-
+function | args | returns | description
+-------- | ---- | ------- | -----------
+[image_shader] | vid, shader_id | | Change the active shader of the specified VID.
+[mesh_shader] | vid, shader_id, slot | | Associate a shader for the specified mesh slot.
+[build_shader] | vshdr, fshdr, label | shader_id | 
+[shader_uniform] |shader_id, symbol, fmtstr, persist, ... | Define a value for the *symbol* slot uniform in the specifed shader, using a *fmtstr* to define how the variadic arguments at the end should map.
 
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WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Fri, 06 Jul 2012 09:31:46 -0000

--- v9
+++ v10
@@ -26,6 +26,7 @@
 Shaders have their own shared namespace that is handled a bit differently from VIDs and AIDs. For one is that there is a compile-time defined upper limit and that each compiled tuple of programs are associated with both a unique text label and an ID. A shader that have been built stays allocated for the remainder of the program lifespan.
 
 A call to [build_shader] such as:
+
 ~~~~
     shid = build_shader( vertprogram, fragprogram, "background");
 ~~~~

WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Fri, 06 Jul 2012 09:31:30 -0000

--- v8
+++ v9
@@ -60,6 +60,7 @@
 texcoord   | per vertex texture coordinate
 
 The default fragment shader (version 120) for the 2D pipeline looks like this: 
+
 ~~~~
 uniform sampler2D map_diffuse;
 varying vec2 texco;

WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Fri, 06 Jul 2012 09:31:14 -0000

--- v7
+++ v8
@@ -59,8 +59,7 @@
 color      | per vertex color
 texcoord   | per vertex texture coordinate
 
-The default fragment shader (version 120) for the 2D pipeline looks like this (unset samplers default to 0, the first texture unit):
-
+The default fragment shader (version 120) for the 2D pipeline looks like this: 
 ~~~~
 uniform sampler2D map_diffuse;
 varying vec2 texco;
@@ -72,8 +71,7 @@
     gl_FragColor = col;
 }
 ~~~~
-
-The default vertex shader for the 2D pipeline looks like this:
+(unset samplers default to 0, the first texture unit). The default vertex shader for the 2D pipeline looks like this:
 
 ~~~~
 uniform mat4 modelview;

WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Fri, 06 Jul 2012 09:30:34 -0000

--- v6
+++ v7
@@ -60,6 +60,7 @@
 texcoord   | per vertex texture coordinate
 
 The default fragment shader (version 120) for the 2D pipeline looks like this (unset samplers default to 0, the first texture unit):
+
 ~~~~
 uniform sampler2D map_diffuse;
 varying vec2 texco;
@@ -73,6 +74,7 @@
 ~~~~
 
 The default vertex shader for the 2D pipeline looks like this:
+
 ~~~~
 uniform mat4 modelview;
 uniform mat4 projection;

WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Fri, 06 Jul 2012 09:30:06 -0000

--- v5
+++ v6
@@ -32,9 +32,9 @@
 
 would try and compile vertprogram and fragprogram into a shader tagged as 'background'. The resulting SHID can then be used with the [image_shader] [build_shader] and [shader_uniform] functions.
 
-The shader compilation step depends on the quality of the compiler in the graphics drivers or GL libraries (e.g. MesaGL) and can be a source of much headache. Having GDebugger  or similar tools ready for debugging purposes is recommended as they can fail for very subtle reasons and error messages aren't always helpful. 
+The shader compilation step depends on the quality of the compiler in the graphics drivers or GL libraries (e.g. MesaGL) and can be a source of much headache. Having GDebugger  or similar tools ready for debugging purposes is recommended as they can fail for very subtle reasons and error messages aren't always helpful. Keep in mind that there is a full C- style preprocessor part in every GLSL shader (e.g. #define, #ifdef, all work ...) 
 
-There are a few formalized ways of passing data to/between shaders, e.g. varying and uniform variables and there are a few hard-coded symbols that Arcan will try and look for, and update whenever relevant. 
+There are a few formalized ways of passing data to/between shaders, e.g. attributes and uniform variables and there are a few hard-coded symbols that Arcan will try and look for, and update whenever relevant. 
 
 User-defined uniforms can be set and manipulated through the [shader_uniform] function.
 
@@ -50,12 +50,41 @@
 timestamp      | int     | current monotonic time value
  
 
-Arcan-defined varyings (will be set if used by shader, vertex and texcoord will almost always be needed):
+Arcan-defined attributes (will be set if used by shader, vertex and texcoord will almost always be needed):
 
-Varying  | Use
--------- | ------------------
-vertex   | object space vertex values
-normal   | object space normal
-color    | per vertex color
-texcoord | per vertex texture coordinate
+Attributes | Use
+--------   | ------------------
+vertex     | object space vertex values
+normal     | object space normal
+color      | per vertex color
+texcoord   | per vertex texture coordinate
 
+The default fragment shader (version 120) for the 2D pipeline looks like this (unset samplers default to 0, the first texture unit):
+~~~~
+uniform sampler2D map_diffuse;
+varying vec2 texco;
+uniform float obj_opacity;
+
+void main(){
+    vec4 col = texture2D(map_diffuse, texco);
+    col.a = col.a * obj_opacity;
+    gl_FragColor = col;
+}
+~~~~
+
+The default vertex shader for the 2D pipeline looks like this:
+~~~~
+uniform mat4 modelview;
+uniform mat4 projection;
+
+attribute vec2 texcoord;
+attribute vec4 vertex;
+
+varying vec2 texco;
+
+void main()
+{
+    texco = texcoord;
+    gl_Position = (projection * modelview) * vertex;
+}
+~~~~

WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Fri, 06 Jul 2012 09:15:34 -0000

--- v4
+++ v5
@@ -50,9 +50,12 @@
 timestamp      | int     | current monotonic time value
  
 
+Arcan-defined varyings (will be set if used by shader, vertex and texcoord will almost always be needed):
+
 Varying  | Use
-----------------------------
+-------- | ------------------
 vertex   | object space vertex values
 normal   | object space normal
 color    | per vertex color
 texcoord | per vertex texture coordinate
+

WikiPage Shader Functions modified by Björn Ståhl

Björn Ståhl — Fri, 06 Jul 2012 09:09:00 -0000

--- v3
+++ v4
@@ -41,7 +41,7 @@
 Arcan-defined uniforms (will be set if used by shader):
 
 Uniform        | Kind    | Use
-----------------------------
+-------------- | ------- | ----------------------------------------
 modelview      | matr4x4 | object->eye transform. 
 projection     | matr4x4 | eye(camera) -> clip transform. 
 texturem       | matr4x4 | not in use currently.