Support interleaved buffers

buffers/buf_usage.go

@@ -0,0 +1,33 @@
+package buffers
+
+import (
+	"fmt"
+
+	"github.com/bloeys/nmage/asserts"
+	"github.com/go-gl/gl/v4.1-core/gl"
+)
+
+type BufUsage int
+
+const (
+	//Buffer is set only once and used many times
+	BufUsageStatic BufUsage = iota
+	//Buffer is changed a lot and used many times
+	BufUsageDynamic
+	//Buffer is set only once and used by the GPU at most a few times
+	BufUsageStream
+)
+
+func (b BufUsage) ToGL() uint32 {
+	switch b {
+	case BufUsageStatic:
+		return gl.STATIC_DRAW
+	case BufUsageDynamic:
+		return gl.DYNAMIC_DRAW
+	case BufUsageStream:
+		return gl.STREAM_DRAW
+	}
+
+	asserts.T(false, fmt.Sprintf("Unexpected BufUsage value '%v'", b))
+	return 0
+}