Merge pull request #144 from PolyFloyd/buffermap

Added MapBuffer convenience functions for slices

1 files changed, 25 insertions, 0 deletions

diff --git a/buffer.go b/buffer.go
index 88936c7..b9cffde 100644
--- a/buffer.go
+++ b/buffer.go
@@ -7,6 +7,7 @@ package gl
 // #include "gl.h"
 import "C"
 import "unsafe"
+import "reflect"
 
 // Buffer Objects
 
@@ -81,6 +82,30 @@ func MapBuffer(target GLenum, access GLenum) unsafe.Pointer {
 	return unsafe.Pointer(C.glMapBuffer(C.GLenum(target), C.GLenum(access)))
 }
 
+// Maps the buffer with MapBuffer() and returns a pointer to the slice pointing
+// to the mapped buffer. See also the MapBuffer<Type> convenience functions.
+// WARNING: This function makes use of reflect.SliceHeader which may reduce
+// portability of your application. See the reflect.SliceHeader documentation
+// for more information.
+func MapBufferSlice(target GLenum, access GLenum, bytesPerElement int) unsafe.Pointer {
+	rawLength := int(GetBufferParameteriv(target, BUFFER_SIZE))
+	return unsafe.Pointer(&reflect.SliceHeader{
+		Data: uintptr(MapBuffer(target, access)),
+		Len:  rawLength / bytesPerElement,
+		Cap:  rawLength / bytesPerElement,
+	})
+}
+
+//  Map a buffer object's data store and return it as a slice
+func MapBufferFloat32(target GLenum, access GLenum) []float32 {
+	return *(*[]float32)(MapBufferSlice(target, access, 4))
+}
+
+//  Map a buffer object's data store and return it as a slice
+func MapBufferUint32(target GLenum, access GLenum) []uint32 {
+	return *(*[]uint32)(MapBufferSlice(target, access, 4))
+}
+
 //  Unmap a buffer object's data store
 func UnmapBuffer(target GLenum) bool {
 	return goBool(C.glUnmapBuffer(C.GLenum(target)))