added BLEND_SET (#1251)

* added BLEND_SET

* renamed BLEND_SET to BLEND_ADD_COLORS

src/raylib.h

@@ -806,7 +806,8 @@ typedef enum {
 typedef enum {
     BLEND_ALPHA = 0,        // Blend textures considering alpha (default)
     BLEND_ADDITIVE,         // Blend textures adding colors
-    BLEND_MULTIPLIED        // Blend textures multiplying colors
+    BLEND_MULTIPLIED,       // Blend textures multiplying colors
+    BLEND_ADD_COLORS        // Blend textures adding colors (alternative)
 } BlendMode;
 
 // Gestures type

src/rlgl.h

@@ -382,7 +382,8 @@ typedef unsigned char byte;
     typedef enum {
         BLEND_ALPHA = 0,
         BLEND_ADDITIVE,
-        BLEND_MULTIPLIED
+        BLEND_MULTIPLIED,
+        BLEND_ADD_COLORS
     } BlendMode;
 
     // Shader location point type
@@ -3558,15 +3559,16 @@ void BeginBlendMode(int mode)
 {
     static int blendMode = 0;   // Track current blending mode
 
-    if ((blendMode != mode) && (mode < 3))
+    if ((blendMode != mode) && (mode < 4))
     {
         rlglDraw();
 
         switch (mode)
         {
             case BLEND_ALPHA: glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); break;
-            case BLEND_ADDITIVE: glBlendFunc(GL_SRC_ALPHA, GL_ONE); break; // Alternative: glBlendFunc(GL_ONE, GL_ONE);
+            case BLEND_ADDITIVE: glBlendFunc(GL_SRC_ALPHA, GL_ONE); break;
             case BLEND_MULTIPLIED: glBlendFunc(GL_DST_COLOR, GL_ONE_MINUS_SRC_ALPHA); break;
+            case BLEND_ADD_COLORS: glBlendFunc(GL_ONE, GL_ONE); break;
             default: break;
         }