Add outline pass to cubes

shaders/src/shader.glsl

@@ -1,41 +0,0 @@
-@header package shaders
-@header import sg "../../sokol/gfx"
-
-@ctype mat4 Mat4
-
-@vs vs
-in vec3 pos;
-in vec2 uv;
-
-layout(binding = 0) uniform VsParams {
-    mat4 mvp;
-    vec4 col;
-};
-
-out vec4 color;
-out vec2 tex_coord;
-
-void main() {
-    gl_Position = mvp * vec4(pos, 1);
-    color = col;
-    tex_coord = uv;
-}
-
-@end
-
-@fs fs
-in vec4 color;
-in vec2 tex_coord;
-
-layout(binding=0) uniform texture2D tex;
-layout(binding=0) uniform sampler smp;
-
-out vec4 frag_color;
-
-void main() {
-    frag_color = texture(sampler2D(tex, smp), tex_coord) * color;
-}
-
-@end
-
-@program main vs fs