120 lines
No EOL
3.7 KiB
Markdown
120 lines
No EOL
3.7 KiB
Markdown
# Shaders {#shaders}
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Shaders are referring to **GPU**-oriented pieces of a program, performing shading and rendering related functions instead of letting the engine handle it.
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In [FTE](https://www.fteqw.org/) you can specify a custom GLSL or HLSL shader using the [program](@ref program) command inside a [Material](@ref materials).
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## Example Shader
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This is a primitive shader file. It includes the vertex and fragment program.
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It will respond to the [diffusemap](@ref diffuseMap) only, which is loaded
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into the **d_f** variable. It can be modified from that point onwards.
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The commented out line will turn all of the output red.
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Give it a try, or something!
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```
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//======= Copyright (c) 2015-2020 Vera Visions LLC. All rights reserved. =======
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//
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// Purpose:
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//
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// Example surface
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//==============================================================================
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!!ver 110
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!!samps diffuse
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#include "sys/defs.h"
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varying vec2 tex_c;
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#ifdef VERTEX_SHADER
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void main ()
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{
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tex_c = v_texcoord; /* get our texture coordinates, which we'll use for the texture2D command */
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gl_Position = ftetransform(); /* place vertex into the place FTE wants us to put them at */
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}
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#endif
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#ifdef FRAGMENT_SHADER
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void main ()
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{
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vec4 d_f = texture2D(s_diffuse, tex_c); /* load the fragment from our diffusemap sample */
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// d_f.rgb = vec3(1.0, 0.0, 0.0); /* turns out fragment (aka pixel) red */
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gl_FragColor = d_f; /* final pixel output is that of d_f */
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}
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#endif
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```
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## Dissecting GLSL shaders
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When we pass `program <shadername>` in our Material, the engine will load `glsl/<shadername>.glsl` to handle the material for us.
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The shader in question needs to define a `main` function for both a vertex and a fragment shader. That's what the **ifdef** pre-processor chunks are for in the above example.
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At some point in the `main` function, we do have to set `gl_Position` and `gl_FragColor` respectively. Those can not be undefined.
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## Frequently Asked Questions
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### Can I keep my vertex and fragment/pixel shader as separate files from one another?
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You can not have separate files handle vertex/fragment programs.
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## Post-processing
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While Nuclide sets up the viewport by itself, it still uses the regular compositing path provided by the engine. So like in most FTE games you can set the console variable `r_postprocshader` to a material of your choice.
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For example, if you define a material called `postproc_test` with this text inside `<gamedir>/scripts/postproc.shader`:
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```
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postproc_test
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{
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program postproc_dither
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{
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map $sourcecolour
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nodepthtest
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}
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}
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```
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... and the shader it is referencing located at `<gamedir>/glsl/postproc_dither.glsl`:
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```
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!!samps screen=0
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!!ver 120
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#include "sys/defs.h"
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varying vec2 texcoord;
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#ifdef VERTEX_SHADER
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void main()
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{
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texcoord = v_texcoord.xy;
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texcoord.y = 1.0 - texcoord.y;
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gl_Position = ftetransform();
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}
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#endif
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#ifdef FRAGMENT_SHADER
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uniform vec2 e_sourcesize;
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void main(void)
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{
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vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
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vec3 col = texture2D(s_screen, texcoord).rgb;
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// limit to 16 bit rendering, alternatively remove this
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// and do whatever else you'd like here
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col.rgb = floor(col.rgb * vec3(32,64,32))/vec3(32,64,32);
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gl_FragColor = vec4(col, 1.0);
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}
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#endif
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```
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Followed by setting the post-processing material via `set r_postprocshader postproc_test` in the console (**SHIFT+ESC**), you will now be processing all framebuffer output through the `postproc_test` material and the `postproc_dither` shader.
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**Of course, a Nuclide game might decide to override the ncView class in such a way to prevent FTE's own post-processing system from being used.**
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@note Use the console command `vid_reload` to reload your material/shader changes while in game! This will save you a lot of time iterating upon them. |