GUI: Box drawing

assets/shaders/gui_box.vert

@@ -0,0 +1,30 @@
+#version 460
+#extension GL_EXT_nonuniform_qualifier : require
+#extension GL_EXT_scalar_block_layout : require
+#extension GL_EXT_shader_16bit_storage : require
+
+out Varyings {
+    layout(location = 0) flat uint instance;
+    layout(location = 1) vec2 positionSSPX;
+} var;
+
+#include "includes/gui_box_common.glsl"
+
+const vec2 VERTICES[4] = vec2[](
+    vec2(0, 1),
+    vec2(1, 1),
+    vec2(0, 0),
+    vec2(1, 0)
+);
+
+#define BOX _Boxes[gl_InstanceIndex]
+#define VERTEX VERTICES[gl_VertexIndex]
+
+void main() {
+    vec2 positionSSPX = VERTEX * BOX.sizePX + BOX.positionSSPX;
+    vec4 positionCS = vec4(_Global.matrixSSPXtoCS * vec3(positionSSPX, 1.0), 0.0, 1.0);
+
+    gl_Position = positionCS;
+    var.instance = gl_InstanceIndex;
+    var.positionSSPX = positionSSPX;
+}