Tech ENABLE_GL_SHADERS_ATTRIBUTES - Added shaders for glsl version 140

(cherry picked from commit prusa3d/PrusaSlicer@76d1d4949b)

resources/shaders/110/printbed.fs

@@ -0,0 +1,34 @@
+#version 110
+
+const vec3 back_color_dark  = vec3(0.235, 0.235, 0.235);
+const vec3 back_color_light = vec3(0.365, 0.365, 0.365);
+
+uniform sampler2D texture;
+uniform bool transparent_background;
+uniform bool svg_source;
+
+varying vec2 tex_coord;
+
+vec4 svg_color()
+{
+    // takes foreground from texture
+    vec4 fore_color = texture2D(texture, tex_coord);
+
+    // calculates radial gradient
+    vec3 back_color = vec3(mix(back_color_light, back_color_dark, smoothstep(0.0, 0.5, length(abs(tex_coord.xy) - vec2(0.5)))));
+
+    // blends foreground with background
+    return vec4(mix(back_color, fore_color.rgb, fore_color.a), transparent_background ? fore_color.a : 1.0);
+}
+
+vec4 non_svg_color()
+{
+    // takes foreground from texture
+    vec4 color = texture2D(texture, tex_coord);
+    return vec4(color.rgb, transparent_background ? color.a * 0.25 : color.a);
+}
+
+void main()
+{
+    gl_FragColor = svg_source ? svg_color() : non_svg_color();
+}