## Shaders on glslsandbox.com

## Varying vectors

Some shaders also have a varying vec2 called "surfacePosition" (although it is not in this shader). This is used to make shaders where you can scroll and zoom. To make this in GameMaker you should another varying vector in vertex shader called "surfacePosition". Then you should be set like this:

**surfacePosition = in_Position.xy*Scroll.zw+Scroll.xy;**"Scroll" will be a vec4 uniform that we'll add next. That code will zoom with z and w components and offset with the x and y.

## Uniforms

GLSL Sandbox shaders already have the uniforms setup. As long as you set them to the right values it should work fine. If the shader has "surfacePosition" then only thing you need to add is a vec4 uniform called "Scroll". This can be used in GameMaker to scroll and zoom.

## Summary

- Change "gl_FragCoord" to "fragCoord"
- Add "fragCoord" and "surfacePosition" (if needed) to vertex shader
- Add "Scroll" vec4 uniform if needed
- Set all uniforms (may include time, resolution or mouse)

**#ifdef GL_ES**

precision mediump float;

#endif

uniform float time;

uniform vec2 resolution;

void main( void ) {

vec2 uv = ( gl_FragCoord.xy / resolution.y );

vec3 color = vec3(fract(sin(dot(floor(uv.xy*32.0+time*2.0),vec2(5.364,6.357)))*357.536));

gl_FragColor = vec4( color, 1.0 );precision mediump float;

#endif

uniform float time;

uniform vec2 resolution;

void main( void ) {

vec2 uv = ( gl_FragCoord.xy / resolution.y );

vec3 color = vec3(fract(sin(dot(floor(uv.xy*32.0+time*2.0),vec2(5.364,6.357)))*357.536));

gl_FragColor = vec4( color, 1.0 );

**Converted GameMaker fragment code:**

**#ifdef GL_ES**

precision mediump float;

#endif

varying vec2 FragCoord;

uniform float time;

uniform vec2 resolution;

void main( void )

{

vec2 uv = ( FragCoord.xy / resolution.y );

vec3 color = vec3(fract(sin(dot(floor(uv.xy*32.0+time*2.0),vec2(5.364,6.357)))*357.536));

gl_FragColor = vec4( color, 1.0 );

}precision mediump float;

#endif

varying vec2 FragCoord;

uniform float time;

uniform vec2 resolution;

void main( void )

{

vec2 uv = ( FragCoord.xy / resolution.y );

vec3 color = vec3(fract(sin(dot(floor(uv.xy*32.0+time*2.0),vec2(5.364,6.357)))*357.536));

gl_FragColor = vec4( color, 1.0 );

}

Converted vertex code:

**attribute vec3 in_Position; // (x,y,z)**

//attribute vec3 in_Normal; // (x,y,z) unused in this shader.

//attribute vec4 in_Colour; // (r,g,b,a) unused in this shader.

//attribute vec2 in_TextureCoord; // (u,v) unused in this shader.

varying vec2 FragCoord;

void main()

{

vec4 object_space_pos = vec4( in_Position.x, in_Position.y, in_Position.z, 1.0);

gl_Position = gm_Matrices[MATRIX_WORLD_VIEW_PROJECTION] * object_space_pos;

FragCoord = in_Position.xy;

}//attribute vec3 in_Normal; // (x,y,z) unused in this shader.

//attribute vec4 in_Colour; // (r,g,b,a) unused in this shader.

//attribute vec2 in_TextureCoord; // (u,v) unused in this shader.

varying vec2 FragCoord;

void main()

{

vec4 object_space_pos = vec4( in_Position.x, in_Position.y, in_Position.z, 1.0);

gl_Position = gm_Matrices[MATRIX_WORLD_VIEW_PROJECTION] * object_space_pos;

FragCoord = in_Position.xy;

}

Here is the example file:

DOWNLOAD EXAMPLE