Add samples ImmutableSampler, InitTexture, InputAttachment (#315)

+ slightly adjust some other samples.

samples/utils/shaders.hpp

@@ -52,6 +52,31 @@ void main()
 }
 )";
 
+// vertex shader with (P)osition and (T)exCoord in and (T)exCoord out
+const std::string vertexShaderText_PT_T = R"(
+#version 400
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (std140, binding = 0) uniform buffer
+{
+  mat4 mvp;
+} uniformBuffer;
+
+layout (location = 0) in vec4 pos;
+layout (location = 1) in vec2 inTexCoord;
+
+layout (location = 0) out vec2 outTexCoord;
+
+void main()
+{
+  outTexCoord = inTexCoord;
+  gl_Position = uniformBuffer.mvp * pos;
+}
+)";
+
+
 // fragment shader with (C)olor in and (C)olor out
 const std::string fragmentShaderText_C_C = R"(
 #version 400
@@ -69,3 +94,22 @@ void main()
 }
 )";
 
+// fragment shader with (T)exCoord in and (C)olor out
+const std::string fragmentShaderText_T_C = R"(
+#version 400
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (binding = 1) uniform sampler2D tex;
+
+layout (location = 0) in vec2 inTexCoord;
+
+layout (location = 0) out vec4 outColor;
+
+void main()
+{
+  outColor = texture(tex, inTexCoord);
+}
+)";
+