[example] Review shaders_spotlight to work on GLSL 100

examples/shaders/resources/shaders/glsl100/spotlight.fs

@@ -4,7 +4,6 @@ precision mediump float;
 
 #define MAX_SPOTS   3
 
-
 struct Spot {
     vec2 pos;		// window coords of spot
     float inner;	// inner fully transparent centre radius
@@ -16,21 +15,21 @@ uniform float screenWidth; // Width of the screen
 
 void main()
 {
-
 	float alpha = 1.0;
-	// get the position of the current fragment (screen coordinates!)
+    
+	// Get the position of the current fragment (screen coordinates!)
 	vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
 	
-	
-	// find out which spotlight is nearest
+	// Find out which spotlight is nearest
 	float d = 65000.0;  // some high value
-	int fi = -1;
+	int fi = -1;        // found index
 
     for (int i = 0; i < MAX_SPOTS; i++)
     {
 		for (int j = 0; j < MAX_SPOTS; j++)
 		{
 			float dj = distance(pos, spots[j].pos) - spots[j].radius + spots[i].radius;
+            
 			if (d > dj) 
 			{
 				d = dj;
@@ -41,23 +40,32 @@ void main()
     
     // d now equals distance to nearest spot...
     // allowing for the different radii of all spotlights
-    if (fi != -1) {
-		
-		if (d > spots[fi].radius) 
+    if (fi == 0) 
     {
-			alpha = 1.0;
-		}
+		if (d > spots[0].radius) alpha = 1.0;
 		else
 		{
-			if (d < spots[fi].inner) 
-			{
-				alpha = 0.0;
+			if (d < spots[0].inner) alpha = 0.0;
+			else alpha = (d - spots[0].inner)/(spots[0].radius - spots[0].inner);
 		}
+	}
+    else if (fi == 1) 
+    {
+		if (d > spots[1].radius) alpha = 1.0;
 		else
 		{
-				alpha = (d - spots[fi].inner) / (spots[fi].radius - spots[fi].inner);
+			if (d < spots[1].inner) alpha = 0.0;
+			else alpha = (d - spots[1].inner)/(spots[1].radius - spots[1].inner);
 		}
 	}
+    else if (fi == 2) 
+    {
+		if (d > spots[2].radius) alpha = 1.0;
+		else
+		{
+			if (d < spots[2].inner) alpha = 0.0;
+			else alpha = (d - spots[2].inner)/(spots[2].radius - spots[2].inner);
+		}
 	}
 	
 	// Right hand side of screen is dimly lit, 

examples/shaders/resources/shaders/glsl330/spotlight.fs

@@ -25,7 +25,6 @@ void main()
 	float alpha = 1.0;
     
 	// Get the position of the current fragment (screen coordinates!)
-	
 	vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
 	
 	// Find out which spotlight is nearest
@@ -37,6 +36,7 @@ void main()
 		for (int j = 0; j < MAX_SPOTS; j++)
 		{
 			float dj = distance(pos, spots[j].pos) - spots[j].radius + spots[i].radius;
+            
 			if (d > dj) 
 			{
 				d = dj;
@@ -47,22 +47,13 @@ void main()
     
     // d now equals distance to nearest spot...
     // allowing for the different radii of all spotlights
-    if (fi != -1) {
-		
-		if (d > spots[fi].radius) 
+    if (fi != -1)
     {
-			alpha = 1.0;
-		}
+		if (d > spots[fi].radius) alpha = 1.0;
 		else
 		{
-			if (d < spots[fi].inner) 
-			{
-				alpha = 0.0;
-			}
-			else 
-			{
-				alpha = (d - spots[fi].inner) / (spots[fi].radius - spots[fi].inner);
-			}
+			if (d < spots[fi].inner) alpha = 0.0;
+			else alpha = (d - spots[fi].inner) / (spots[fi].radius - spots[fi].inner);
 		}
 	}