[mixer] #503 Fixed bug where already drawn GL_QUADS were not composited against,...

diff --git a/accelerator/ogl/image/image_kernel.cpp b/accelerator/ogl/image/image_kernel.cpp
index 6caab47480deea00ce7dc94dab525632889440c1..42c19fea1ee9c65a20a95bde1bafc57509e926aa 100644 (file)
--- a/accelerator/ogl/image/image_kernel.cpp
+++ b/accelerator/ogl/image/image_kernel.cpp
@@ -374,15 +374,7 @@ struct image_kernel::impl
                        glScissor(static_cast<int>(m_p[0] * w), static_cast<int>(m_p[1] * h), std::max(0, static_cast<int>(m_s[0] * w)), std::max(0, static_cast<int>(m_s[1] * h)));
                }
 
-               // Synchronize and set render target
-
-               if (blend_modes_)
-               {
-                       // http://www.opengl.org/registry/specs/NV/texture_barrier.txt
-                       // This allows us to use framebuffer (background) both as source and target while blending.
-                       glTextureBarrierNV();
-               }
-
+               // Set render target
                params.background->attach();
 
                // Perspective correction
@@ -448,7 +440,20 @@ struct image_kernel::impl
 
                                glVertexPointer(2, GL_DOUBLE, stride, vertex_coord_ptr);
                                glTexCoordPointer(4, GL_DOUBLE, stride, texture_coord_ptr);
-                               glDrawArrays(GL_QUADS, 0, static_cast<GLsizei>(coords.size())); //each vertex is four doubles.
+
+                               if (blend_modes_)
+                               {
+                                       for (int i = 0; i < coords.size(); i += 4)
+                                       {
+                                               // http://www.opengl.org/registry/specs/NV/texture_barrier.txt
+                                               // This allows us to use framebuffer (background) both as source and target while blending.
+                                               glTextureBarrierNV();
+                                               glDrawArrays(GL_QUADS, i, 4);
+                                       }
+                               }
+                               else
+                                       glDrawArrays(GL_QUADS, 0, static_cast<GLsizei>(coords.size()));
+
 
                                glDisableClientState(GL_TEXTURE_COORD_ARRAY);
                                glDisableClientState(GL_VERTEX_ARRAY);