Examples: SDL2+GL3: Fix blend func state save/restore (#1120)

examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp

@@ -45,12 +45,14 @@ void ImGui_ImplSdlGL3_RenderDrawLists(ImDrawData* draw_data)
     GLint last_array_buffer; glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer);
     GLint last_element_array_buffer; glGetIntegerv(GL_ELEMENT_ARRAY_BUFFER_BINDING, &last_element_array_buffer);
     GLint last_vertex_array; glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array);
-    GLint last_blend_src; glGetIntegerv(GL_BLEND_SRC, &last_blend_src);
-    GLint last_blend_dst; glGetIntegerv(GL_BLEND_DST, &last_blend_dst);
+    GLint last_blend_src_rgb; glGetIntegerv(GL_BLEND_SRC_RGB, &last_blend_src_rgb);
+    GLint last_blend_dst_rgb; glGetIntegerv(GL_BLEND_DST_RGB, &last_blend_dst_rgb);
+    GLint last_blend_src_alpha; glGetIntegerv(GL_BLEND_SRC_ALPHA, &last_blend_src_alpha);
+    GLint last_blend_dst_alpha; glGetIntegerv(GL_BLEND_DST_ALPHA, &last_blend_dst_alpha);
     GLint last_blend_equation_rgb; glGetIntegerv(GL_BLEND_EQUATION_RGB, &last_blend_equation_rgb);
     GLint last_blend_equation_alpha; glGetIntegerv(GL_BLEND_EQUATION_ALPHA, &last_blend_equation_alpha);
     GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport);
-    GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box); 
+    GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box);
     GLboolean last_enable_blend = glIsEnabled(GL_BLEND);
     GLboolean last_enable_cull_face = glIsEnabled(GL_CULL_FACE);
     GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST);
@@ -84,10 +86,10 @@ void ImGui_ImplSdlGL3_RenderDrawLists(ImDrawData* draw_data)
         const ImDrawIdx* idx_buffer_offset = 0;
 
         glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
-        glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)cmd_list->VtxBuffer.Size * sizeof(ImDrawVert), (GLvoid*)cmd_list->VtxBuffer.Data, GL_STREAM_DRAW);
+        glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)cmd_list->VtxBuffer.Size * sizeof(ImDrawVert), (const GLvoid*)cmd_list->VtxBuffer.Data, GL_STREAM_DRAW);
 
         glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_ElementsHandle);
-        glBufferData(GL_ELEMENT_ARRAY_BUFFER, (GLsizeiptr)cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx), (GLvoid*)cmd_list->IdxBuffer.Data, GL_STREAM_DRAW);
+        glBufferData(GL_ELEMENT_ARRAY_BUFFER, (GLsizeiptr)cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx), (const GLvoid*)cmd_list->IdxBuffer.Data, GL_STREAM_DRAW);
 
         for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
         {
@@ -114,7 +116,7 @@ void ImGui_ImplSdlGL3_RenderDrawLists(ImDrawData* draw_data)
     glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, last_element_array_buffer);
     glBlendEquationSeparate(last_blend_equation_rgb, last_blend_equation_alpha);
-    glBlendFunc(last_blend_src, last_blend_dst);
+    glBlendFuncSeparate(last_blend_src_rgb, last_blend_dst_rgb, last_blend_src_alpha, last_blend_dst_alpha);
     if (last_enable_blend) glEnable(GL_BLEND); else glDisable(GL_BLEND);
     if (last_enable_cull_face) glEnable(GL_CULL_FACE); else glDisable(GL_CULL_FACE);
     if (last_enable_depth_test) glEnable(GL_DEPTH_TEST); else glDisable(GL_DEPTH_TEST);