Revert "internal/graphicsdriver/opengl/gl: refactoring"

This reverts commit a1ad87a262.

Reason: compile error

internal/graphicsdriver/opengl/context_gl.go

@@ -290,8 +290,8 @@ func (c *context) newShader(shaderType uint32, source string) (shader, error) {
 	if s == 0 {
 		return 0, fmt.Errorf("opengl: glCreateShader failed: shader type: %d", shaderType)
 	}
-	cSources, free := gl.CStr(source)
-	gl.ShaderSource(uint32(s), 1, &cSources, nil)
+	cSources, free := gl.Strs(source + "\x00")
+	gl.ShaderSource(uint32(s), 1, cSources, nil)
 	free()
 	gl.CompileShader(s)
 
@@ -325,8 +325,8 @@ func (c *context) newProgram(shaders []shader, attributes []string) (program, er
 	}
 
 	for i, name := range attributes {
-		l, free := gl.CStr(name)
-		gl.BindAttribLocation(p, uint32(i), l)
+		l, free := gl.Strs(name + "\x00")
+		gl.BindAttribLocation(p, uint32(i), *l)
 		free()
 	}
 
@@ -360,8 +360,8 @@ func (c *context) deleteProgram(p program) {
 }
 
 func (c *context) getUniformLocationImpl(p program, location string) uniformLocation {
-	l, free := gl.CStr(location)
-	uniform := uniformLocation(gl.GetUniformLocation(uint32(p), l))
+	l, free := gl.Strs(location + "\x00")
+	uniform := uniformLocation(gl.GetUniformLocation(uint32(p), *l))
 	free()
 	return uniform
 }

internal/graphicsdriver/opengl/gl/conversions_cgo.go

@@ -17,14 +17,27 @@ func GoStr(cstr *byte) string {
 	return C.GoString((*C.char)(unsafe.Pointer(cstr)))
 }
 
-// CStr takes a Go string (with or without null-termination)
-// and returns the C counterpart.
+// Strs takes a list of Go strings (with or without null-termination) and
+// returns their C counterpart.
 //
-// The returned free function must be called once you are done using the string
+// The returned free function must be called once you are done using the strings
 // in order to free the memory.
-func CStr(str string) (cstr *byte, free func()) {
-	cs := C.CString(str)
-	return cs, func() {
-		C.free(unsafe.Pointer(cs))
+//
+// If no strings are provided as a parameter this function will panic.
+func Strs(strs ...string) (cstrs **byte, free func()) {
+	if len(strs) == 0 {
+		panic("gl: expected at least 1 string at Strs")
+	}
+
+	css := make([]*byte, 0, len(strs))
+	for _, str := range strs {
+		cs := C.CString(str)
+		css = append(css, (*byte)(unsafe.Pointer(cs)))
+	}
+
+	return (**byte)(&css[0]), func() {
+		for _, cs := range css {
+			C.free(unsafe.Pointer(cs))
+		}
 	}
 }

internal/graphicsdriver/opengl/gl/conversions_nocgo.go

@@ -26,18 +26,31 @@ func GoStr(cstr *byte) string {
 	return ""
 }
 
-// CStr takes a Go string (with or without null-termination)
-// and returns the C counterpart.
+// Strs takes a list of Go strings (with or without null-termination) and
+// returns their C counterpart.
 //
-// The returned free function must be called once you are done using the string
+// The returned free function must be called once you are done using the strings
 // in order to free the memory.
-func CStr(str string) (cstr *byte, free func()) {
-	bs := []byte(str)
-	if len(bs) == 0 || bs[len(bs)-1] != 0 {
-		bs = append(bs, 0)
+//
+// If no strings are provided as a parameter this function will panic.
+func Strs(strs ...string) (cstrs **byte, free func()) {
+	if len(strs) == 0 {
+		panic("gl: expected at least 1 string at Strs")
 	}
-	return &bs[0], func() {
-		runtime.KeepAlive(bs)
-		bs = nil
+
+	pinned := make([][]byte, 0, len(strs))
+	ptrs := make([]*byte, 0, len(strs))
+	for _, str := range strs {
+		bs := []byte(str)
+		if len(bs) == 0 || bs[len(bs)-1] != 0 {
+			bs = append(bs, 0)
+		}
+		pinned = append(pinned, bs)
+		ptrs = append(ptrs, &bs[0])
+	}
+
+	return &ptrs[0], func() {
+		runtime.KeepAlive(pinned)
+		pinned = nil
 	}
 }