DrawBuffer: Basic scissor support.

gfx_es2/draw_buffer.cpp

@@ -13,6 +13,7 @@
 #include <algorithm>
 #include <cmath>
 
+#include "base/display.h"
 #include "base/logging.h"
 #include "math/math_util.h"
 #include "gfx_es2/draw_buffer.h"
@@ -360,3 +361,15 @@ void DrawBuffer::EnableBlend(bool enable) {
 	else
 		glDisable(GL_BLEND);
 }
+
+void DrawBuffer::SetClipRect(float x, float y, float w, float h)
+{
+	// Sigh, OpenGL is upside down.
+	glScissor(x, g_yres - y, w, h);
+	glEnable(GL_SCISSOR_TEST);
+}
+
+void DrawBuffer::NoClip()
+{
+	glDisable(GL_SCISSOR_TEST);
+}

gfx_es2/draw_buffer.h

@@ -97,6 +97,13 @@ class DrawBuffer {
 	// Utility to avoid having to include gl.h just for this in UI code.
 	void EnableBlend(bool enable);
 
+
+	// Rectangular clipping, implemented using scissoring.
+	// Must flush before and after.
+	void SetClipRect(float x1, float y1, float x2, float y2);
+	void NoClip();
+
+
  private:
 	void DoAlign(int flags, float *x, float *y, float *w, float *h);
   struct Vertex {