Add uniform values

shaders/frag.glsl

@@ -3,6 +3,8 @@
 in vec3 vert_colours;
 out vec4 color;
 
+uniform float u_offset;
+
 void main() {
-  color = vec4(vert_colours.r, vert_colours.g, vert_colours.b, 1.0f);
+  color = vec4(vert_colours.r, vert_colours.g + u_offset, vert_colours.b, 1.0f);
 };

shaders/vert.glsl

@@ -3,9 +3,11 @@
 layout(location=0) in vec3 position;
 layout(location=1) in vec3 vert_colour;
 
+uniform float u_offset;
+
 out vec3 vert_colours;
 
 void main() {
   vert_colours = vert_colour;
-  gl_Position = vec4(position.x, position.y, position.z, 1.0f);
+  gl_Position = vec4(position.x, position.y + u_offset, position.z, 1.0f);
 };