Make a number of key optimizations

- Changed glMapBuffer to glMapBufferRange to allow invalidation.  Using
   just glMapBuffer alone was causing some unacceptable stalls.

 - Changed dynamic buffers from GL_DYNAMIC_WRITE to GL_STREAM_WRITE
   because I had misunderstood the OpenGL specification

 - Added _OPENGL and _D3D11 builtin preprocessor macros to effects to
   allow special processing if needed

 - Added fmod support to shaders (NOTE: D3D and GL do not function
   identically with negative numbers when using this.  Positive numbers
   however function identically)

 - Created a planar conversion shader that converts from packed YUV to
   planar 420 right on the GPU without any CPU processing.  Reduces
   required GPU download size to approximately 37.5% of its normal rate
   as well.  GPU usage down by 10 entire percentage points despite the
   extra required pass.

libobs-opengl/gl-exports.h

@@ -19,6 +19,7 @@
 
 #include <util/c99defs.h>
 
+EXPORT const char *device_preprocessor_name(void);
 EXPORT device_t device_create(struct gs_init_data *data);
 EXPORT void device_destroy(device_t device);
 EXPORT void device_entercontext(device_t device);

libobs-opengl/gl-helpers.c

@@ -155,8 +155,12 @@ bool update_buffer(GLenum target, GLuint buffer, void *data, size_t size)
 	if (!gl_bind_buffer(target, buffer))
 		return false;
 
-	ptr = glMapBuffer(target, GL_WRITE_ONLY);
-	success = gl_success("glMapBuffer");
+	/* glMapBufferRange with these flags will actually give far better
+	 * performance than a plain glMapBuffer call */
+	ptr = glMapBufferRange(target, 0, size,
+			GL_MAP_WRITE_BIT |
+			GL_MAP_INVALIDATE_BUFFER_BIT);
+	success = gl_success("glMapBufferRange");
 	if (success && ptr) {
 		memcpy(ptr, data, size);
 		glUnmapBuffer(target);

libobs-opengl/gl-shaderparser.c

@@ -239,7 +239,7 @@ static inline void gl_write_structs(struct gl_shader_parser *glsp)
  *   clip     -> (unsupported)
  *   ddx      -> dFdx
  *   ddy      -> dFdy
- *   fmod     -> (unsupported)
+ *   fmod     -> mod (XXX: these are different if sign is negative)
  *   frac     -> fract
  *   lerp     -> mix
  *   lit      -> (unsupported)
@@ -367,6 +367,8 @@ static bool gl_write_intrinsic(struct gl_shader_parser *glsp,
 		dstr_cat(&glsp->gl_string, "fract");
 	} else if (strref_cmp(&token->str, "lerp") == 0) {
 		dstr_cat(&glsp->gl_string, "mix");
+	} else if (strref_cmp(&token->str, "fmod") == 0) {
+		dstr_cat(&glsp->gl_string, "mod");
 	} else if (strref_cmp(&token->str, "rsqrt") == 0) {
 		dstr_cat(&glsp->gl_string, "inversesqrt");
 	} else if (strref_cmp(&token->str, "saturate") == 0) {

libobs-opengl/gl-subsystem.c

@@ -163,6 +163,11 @@ void convert_sampler_info(struct gs_sampler_state *sampler,
 	               info->max_anisotropy, sampler->max_anisotropy);
 }
 
+const char *device_preprocessor_name(void)
+{
+	return "_OPENGL";
+}
+
 device_t device_create(struct gs_init_data *info)
 {
 	struct gs_device *device = bzalloc(sizeof(struct gs_device));

libobs-opengl/gl-vertexbuffer.c

@@ -20,7 +20,7 @@
 
 static bool create_buffers(struct gs_vertex_buffer *vb)
 {
-	GLenum usage = vb->dynamic ? GL_DYNAMIC_DRAW : GL_STATIC_DRAW;
+	GLenum usage = vb->dynamic ? GL_STREAM_DRAW : GL_STATIC_DRAW;
 	size_t i;
 
 	if (!gl_create_buffer(GL_ARRAY_BUFFER, &vb->vertex_buffer,