Added shaders for OpenGL ES

resources/shaders/ES/flat_clip.vs

@@ -0,0 +1,23 @@
+#version 100
+
+uniform mat4 view_model_matrix;
+uniform mat4 projection_matrix;
+uniform mat4 volume_world_matrix;
+
+// Clipping plane, x = min z, y = max z. Used by the FFF and SLA previews to clip with a top / bottom plane.
+uniform vec2 z_range;
+// Clipping plane - general orientation. Used by the SLA gizmo.
+uniform vec4 clipping_plane;
+
+attribute vec3 v_position;
+
+varying vec3 clipping_planes_dots;
+
+void main()
+{
+    // Fill in the scalars for fragment shader clipping. Fragments with any of these components lower than zero are discarded.
+    vec4 world_pos = volume_world_matrix * vec4(v_position, 1.0);
+    clipping_planes_dots = vec3(dot(world_pos, clipping_plane), world_pos.z - z_range.x, z_range.y - world_pos.z);
+
+    gl_Position = projection_matrix * view_model_matrix * vec4(v_position, 1.0);
+}