Add all gl BufUsage values+support bufusage in ubo

buffers/buf_usage.go

@@ -9,25 +9,48 @@ import (
 
 type BufUsage int
 
+// Full docs for buffer usage can be found here: https://registry.khronos.org/OpenGL-Refpages/gl4/html/glBufferData.xhtml
 const (
 	BufUsage_Unknown BufUsage = iota
 
 	//Buffer is set only once and used many times
-	BufUsage_Static
+	BufUsage_Static_Draw
 	//Buffer is changed a lot and used many times
-	BufUsage_Dynamic
+	BufUsage_Dynamic_Draw
 	//Buffer is set only once and used by the GPU at most a few times
-	BufUsage_Stream
+	BufUsage_Stream_Draw
+
+	BufUsage_Static_Read
+	BufUsage_Dynamic_Read
+	BufUsage_Stream_Read
+
+	BufUsage_Static_Copy
+	BufUsage_Dynamic_Copy
+	BufUsage_Stream_Copy
 )
 
 func (b BufUsage) ToGL() uint32 {
 	switch b {
-	case BufUsage_Static:
+	case BufUsage_Static_Draw:
 		return gl.STATIC_DRAW
-	case BufUsage_Dynamic:
+	case BufUsage_Dynamic_Draw:
 		return gl.DYNAMIC_DRAW
-	case BufUsage_Stream:
+	case BufUsage_Stream_Draw:
 		return gl.STREAM_DRAW
+
+	case BufUsage_Static_Read:
+		return gl.STATIC_READ
+	case BufUsage_Dynamic_Read:
+		return gl.DYNAMIC_READ
+	case BufUsage_Stream_Read:
+		return gl.STREAM_READ
+
+	case BufUsage_Static_Copy:
+		return gl.STATIC_COPY
+	case BufUsage_Dynamic_Copy:
+		return gl.DYNAMIC_COPY
+	case BufUsage_Stream_Copy:
+		return gl.STREAM_COPY
 	}
 
 	assert.T(false, fmt.Sprintf("Unexpected BufUsage value '%v'", b))