fixes texture formats for GLES2/GLES3

src/nanovg_gl.h

@@ -593,7 +593,13 @@ static int glnvg__renderCreateTexture(void* uptr, int type, int w, int h, const
 	if (type == NVG_TEXTURE_RGBA)
 		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
 	else
+#if defined(NANOVG_GLES2)
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, w, h, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
+#elif defined(NANOVG_GLES3)
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, w, h, 0, GL_RED, GL_UNSIGNED_BYTE, data);
+#else
 		glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, w, h, 0, GL_RED, GL_UNSIGNED_BYTE, data);
+#endif
 
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
@@ -647,7 +653,11 @@ static int glnvg__renderUpdateTexture(void* uptr, int image, int x, int y, int w
 	if (tex->type == NVG_TEXTURE_RGBA)
 		glTexSubImage2D(GL_TEXTURE_2D, 0, x,y, w,h, GL_RGBA, GL_UNSIGNED_BYTE, data);
 	else
+#ifdef NANOVG_GLES2
+		glTexSubImage2D(GL_TEXTURE_2D, 0, x,y, w,h, GL_LUMINANCE, GL_UNSIGNED_BYTE, data);
+#else
 		glTexSubImage2D(GL_TEXTURE_2D, 0, x,y, w,h, GL_RED, GL_UNSIGNED_BYTE, data);
+#endif
 
 	glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
 #ifndef NANOVG_GLES2