Added glsl 100 and 120 shaders to lightmap example. (#3543)

* Added glsl 100 and 120 shaders to lightmap example.

* Fixed lightmap example resource loading on web.

examples/shaders/resources/shaders/glsl100/lightmap.fs

@@ -0,0 +1,22 @@
+#version 100
+
+precision mediump float;
+
+// Input vertex attributes (from vertex shader)
+varying vec2 fragTexCoord;
+varying vec2 fragTexCoord2;
+varying vec3 fragPosition;
+varying vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform sampler2D texture1;
+
+void main()
+{
+    // Texel color fetching from texture sampler
+    vec4 texelColor = texture2D(texture0, fragTexCoord);
+    vec4 texelColor2 = texture2D(texture1, fragTexCoord2);
+
+    gl_FragColor = texelColor * texelColor2;
+}

examples/shaders/resources/shaders/glsl100/lightmap.vs

@@ -0,0 +1,31 @@
+#version 100
+
+// Input vertex attributes
+attribute vec3 vertexPosition;
+attribute vec2 vertexTexCoord;
+attribute vec2 vertexTexCoord2;
+attribute vec4 vertexColor;
+
+// Input uniform values
+uniform mat4 mvp;
+uniform mat4 matModel;
+
+// Output vertex attributes (to fragment shader)
+varying vec3 fragPosition;
+varying vec2 fragTexCoord;
+varying vec2 fragTexCoord2;
+varying vec4 fragColor;
+
+// NOTE: Add here your custom variables
+
+void main()
+{
+    // Send vertex attributes to fragment shader
+    fragPosition = vec3(matModel*vec4(vertexPosition, 1.0));
+    fragTexCoord = vertexTexCoord;
+    fragTexCoord2 = vertexTexCoord2;
+    fragColor = vertexColor;
+
+    // Calculate final vertex position
+    gl_Position = mvp*vec4(vertexPosition, 1.0);
+}