as per request spotlight example (#1146)

Co-authored-by: codifies <nospam@antispam.com>

examples/Makefile

@@ -456,7 +456,8 @@ SHADERS = \
     shaders/shaders_eratosthenes \
     shaders/shaders_basic_lighting \
     shaders/shaders_fog \
-    shaders/shaders_simple_mask
+    shaders/shaders_simple_mask \
+    shaders/shaders_spotlight
     
 AUDIO = \
     audio/audio_module_playing \

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

@@ -0,0 +1,52 @@
+#version 100
+
+precision mediump float;
+
+#define     MAX_SPOTS			4
+#define		RADIUS				256.0
+#define		INNER				200.0
+
+// Inputs
+// array of spotlight positions
+uniform vec2 spots[MAX_SPOTS];
+
+uniform float screenWidth; // width of the screen
+
+void main()
+{
+
+	float alpha;
+	// get the position of the current fragment (screen coordinates!)
+	vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
+
+	
+	// find out which spotlight is nearest
+	float d = 65000.0; // some high value
+	float di = 0.0;
+
+    for (int i = 0; i < MAX_SPOTS; i++)
+    {
+		di = distance(pos, spots[i]);
+		if (d > di) d = di;
+    }
+    
+    // d now equals distance to nearest spot...
+    if (d > RADIUS) {
+		alpha = 1.0;
+	} else {
+		if (d < INNER) {
+			alpha = 0.0;
+		} else {
+			alpha = (d - INNER) / (RADIUS - INNER);
+		}
+	}
+	
+	// right hand side of screen is dimly lit, could make the
+	// threshold value user definable.
+	if (pos.x > screenWidth/2.0 && alpha > 0.9) {
+		alpha = 0.9;
+	}
+
+	// could make the black out colour user definable...
+    gl_FragColor = vec4( 0, 0, 0, alpha);
+}

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

@@ -0,0 +1,53 @@
+#version 330
+
+// Output fragment color
+out vec4 finalColor;
+
+#define     MAX_SPOTS			4
+#define		RADIUS				256
+#define		INNER				200
+
+// Inputs
+// array of spotlight positions
+uniform vec2 spots[MAX_SPOTS];
+
+uniform float screenWidth; // width of the screen
+
+void main()
+{
+
+	float alpha;
+	// get the position of the current fragment (screen coordinates!)
+	vec2 pos = vec2(gl_FragCoord.x, gl_FragCoord.y);
+
+	
+	// find out which spotlight is nearest
+	float d = 65000; // some high value
+	float di = 0;
+
+    for (int i = 0; i < MAX_SPOTS; i++)
+    {
+		di = distance(pos, spots[i]);
+		if (d > di) d = di;
+    }
+    
+    // d now equals distance to nearest spot...
+    if (d > RADIUS) {
+		alpha = 1.0;
+	} else {
+		if (d < INNER) {
+			alpha = 0.0;
+		} else {
+			alpha = (d - INNER) / (RADIUS - INNER);
+		}
+	}
+	
+	// right hand side of screen is dimly lit, could make the
+	// threshold value user definable.
+	if (pos.x>screenWidth/2.0 && alpha >0.9) {
+		alpha = 0.9;
+	}
+
+	// could make the black out colour user definable...
+    finalColor = vec4( 0, 0, 0, alpha);
+}

examples/shaders/shaders_spotlight.c

@@ -0,0 +1,225 @@
+/*
+ * Copyright (c) 2019 Chris Camacho (codifies -  http://bedroomcoders.co.uk/)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+ 
+/* The shader makes alpha holes in the forground to give the apearance of a top
+ * down look at a spotlight casting a pool of light...
+ * 
+ * The right hand side of the screen there is just enough light to see whats
+ * going on without the spot light, great for a stealth type game where you
+ * have to avoid the spotlights.
+ * 
+ * The left hand side of the screen is in pitch dark except for where the spotlights
+ * are.
+ * 
+ * Although this example doesn't scale like the letterbox example, you could integrate
+ * the two techniques, but by scaling the actual colour of the render texture rather
+ * than using alpha as a mask.
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "raylib.h"
+#include "raymath.h"
+
+#if defined(PLATFORM_DESKTOP)
+    #define GLSL_VERSION            330
+#else   // PLATFORM_RPI, PLATFORM_ANDROID, PLATFORM_WEB
+    #define GLSL_VERSION            100
+#endif
+
+// single digit only!
+#define MAXSPOT 4
+
+#define numStars 400
+
+#define screenWidth 1280
+#define screenHeight 720
+
+// the stars in the star field have a position and velocity
+typedef struct star {
+    Vector2 pos;
+    Vector2 vel;
+} star;
+
+
+void updateStar(star *s);
+void resetStar(star *s);
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    star stars[numStars];
+
+    for (int n=0; n < numStars; n++) {
+        resetStar(&stars[n]);
+    }
+
+    // progress all the stars on, so they don't all start in the centre
+    for (int m=0; m < screenWidth / 2.0; m++) {
+        for (int n=0; n<numStars; n++) {
+            updateStar(&stars[n]);
+        }
+    }
+
+    //SetConfigFlags(FLAG_FULLSCREEN_MODE);
+    InitWindow(screenWidth, screenHeight, "raylib - test");
+
+    Texture rayTex = LoadTexture("resources/raysan.png"); 
+
+    // frame counter
+    int frame = 0;
+
+    unsigned int spotLoc[MAXSPOT]; // shader locations    
+ 
+    Vector2 spotPos[MAXSPOT];  // position and velocity
+    Vector2 spotVel[MAXSPOT];
+       
+    // use default vert shader
+    Shader spotShader = LoadShader(0, FormatText("resources/shaders/glsl%i/spotlight.fs", GLSL_VERSION));
+    
+	// get the locations of spots in the shader
+    char spotName[32] = "spots[x]\0";
+    for (int i = 0; i<MAXSPOT; i++) {
+		spotName[6] = '0' + i;
+		spotLoc[i] = GetShaderLocation(spotShader, spotName);
+	}
+	
+	// tell the shader how wide the screen is so we can have
+	// a pitch black half and a dimly lit half.
+	{
+		unsigned int wLoc = GetShaderLocation(spotShader, "screenWidth");
+		float sw = screenWidth;
+		SetShaderValue(spotShader, wLoc, &sw, UNIFORM_FLOAT);
+	}
+
+    // randomise the locations and velocities of the spotlights
+    for (int i=0; i<MAXSPOT; i++) {
+		spotPos[i].x = GetRandomValue(128, screenWidth-128);
+		spotPos[i].y = GetRandomValue(128, screenHeight-128);
+		spotVel[i] = (Vector2){0, 0};
+		while (fabs(spotVel[i].x)+fabs(spotVel[i].y)<2) {
+			spotVel[i].x = GetRandomValue(-40,40)/10.0;
+			spotVel[i].y = GetRandomValue(-40,40)/10.0;
+		}
+	}
+  
+
+    SetTargetFPS(60);               // Set  to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+
+        frame ++;
+
+		// move the stars, resetting them if the go offscreen
+        for (int n=0; n<numStars; n++) {
+            updateStar(&stars[n]);
+        }
+
+		// update the spots, send them to the shader
+		for (int i=0; i<MAXSPOT; i++) {
+
+			spotPos[i].x += spotVel[i].x;					
+			spotPos[i].y += spotVel[i].y;
+			
+			if (spotPos[i].x < 128) spotVel[i].x = -spotVel[i].x;					
+			if (spotPos[i].x > screenWidth-128) spotVel[i].x = -spotVel[i].x;					
+			if (spotPos[i].y < 128) spotVel[i].y = -spotVel[i].y;					
+			if (spotPos[i].y > screenHeight-128) spotVel[i].y = -spotVel[i].y;
+			
+			SetShaderValue(spotShader, spotLoc[i], &spotPos[i].x, UNIFORM_VEC2);				
+		}
+			
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground((Color){0,32,128,255});
+
+			// stars and bobs
+            for (int n=0; n<numStars; n++) {
+				// single pixel is just too small these days!
+                DrawRectangle(stars[n].pos.x, stars[n].pos.y, 2, 2, WHITE);
+            }
+
+            for (int i=0; i<16; i++) {
+                DrawTexture(rayTex,
+                    (screenWidth/2.0)+cos((frame+i*8)/51.45)*(screenWidth/2.2)-32,
+                    (screenHeight/2.0)+sin((frame+i*8)/17.87)*(screenHeight/4.2),
+                    WHITE);
+            }
+
+			// spot lights
+			BeginShaderMode(spotShader);
+				// instead of a blank rectangle you could render here
+				// a render texture of the full screen used to do screen
+				// scaling (slight adjustment to shader would be required
+				// to actually pay attention to the colour!)
+				DrawRectangle(0,0,screenWidth,screenHeight,WHITE);
+			EndShaderMode();
+
+            DrawFPS(10, 10);
+
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+
+    UnloadTexture(rayTex);
+
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}
+
+
+void resetStar(star *s)
+{
+    (*s).pos = (Vector2){screenWidth/2.0, screenHeight/2.0 };
+    do {
+        (*s).vel.x = (float)GetRandomValue(-1000,1000) / 100.0;
+        (*s).vel.y = (float)GetRandomValue(-1000,1000) / 100.0;
+    } while (!(fabs((*s).vel.x)+fabs((*s).vel.y)>1));
+    (*s).pos = Vector2Add( (*s).pos,
+                    Vector2MultiplyV((*s).vel,(Vector2){8,8} ));
+}
+
+void updateStar(star *s)
+{
+    (*s).pos = Vector2Add((*s).pos, (*s).vel);
+    if ((*s).pos.x < 0 || (*s).pos.x > screenWidth ||
+        (*s).pos.y < 0 || (*s).pos.y > screenHeight) {
+            resetStar(s);
+    }
+}
+
+