progs/fpglsl: couple more tests

progs/fpglsl/tex-multi.glsl

@@ -0,0 +1,15 @@
+// Multi-texture fragment shader
+// Brian Paul
+
+// Composite second texture over first.
+// We're assuming the 2nd texture has a meaningful alpha channel.
+
+uniform sampler2D tex1;
+uniform sampler2D tex2;
+
+void main()
+{
+   vec4 t1 = texture2D(tex1, gl_Color.xy);
+   vec4 t2 = texture2D(tex2, gl_Color.yz);
+   gl_FragColor = mix(t1, t2, t2.w);
+}

progs/fpglsl/tex.glsl

@@ -0,0 +1,6 @@
+uniform sampler2D tex1;
+
+void main()
+{
+   gl_FragColor = texture2D(tex1, gl_Color.xy);
+}