more tests

tests/Shader/inner/triangle.glsl

@@ -0,0 +1,13 @@
+#version 450
+
+layout(location = 0) out vec3 color;
+
+void main() {
+    vec2 positions[3] = vec2[](
+        vec2( 0.0, -0.5),
+        vec2( 0.5,  0.5),
+        vec2(-0.5,  0.5)
+    );
+    gl_Position = vec4(positions[gl_VertexIndex], 0.0, 1.0);
+    color = vec3(1.0, 0.0, 0.0);
+}