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Examples: OpenGL2/3: save/restore some more state correctly.

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Might save an hour of staring at blank-screen to 5% of the population,
worth it.
This commit is contained in:
ocornut
2015-08-29 17:44:52 +01:00
parent f2c68109a6
commit 0bb46c824e
3 changed files with 33 additions and 15 deletions
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32
examples/opengl3_example/imgui_impl_glfw_gl3.cpp
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@ -30,10 +30,15 @@ static unsigned int g_VboHandle = 0, g_VaoHandle = 0, g_ElementsHandle = 0;
// - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
static void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawData* draw_data)
{
// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled
GLint last_program, last_texture;
// Backup GL state
GLint last_program, last_texture, last_array_buffer, last_element_array_buffer, last_vertex_array;
glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer);
glGetIntegerv(GL_ELEMENT_ARRAY_BUFFER_BINDING, &last_element_array_buffer);
glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array);
// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled
glEnable(GL_BLEND);
glBlendEquation(GL_FUNC_ADD);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
@ -87,13 +92,13 @@ static void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawData* draw_data)
}
}
// Restore modified state
glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
// Restore modified GL state
glUseProgram(last_program);
glDisable(GL_SCISSOR_TEST);
glBindTexture(GL_TEXTURE_2D, last_texture);
glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, last_element_array_buffer);
glBindVertexArray(last_vertex_array);
glDisable(GL_SCISSOR_TEST);
}
static const char* ImGui_ImplGlfwGL3_GetClipboardText()
@ -162,6 +167,12 @@ void ImGui_ImplGlfwGL3_CreateFontsTexture()
bool ImGui_ImplGlfwGL3_CreateDeviceObjects()
{
// Backup GL state
GLint last_texture, last_array_buffer, last_vertex_array;
glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer);
glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array);
const GLchar *vertex_shader =
"#version 330\n"
"uniform mat4 ProjMtx;\n"
@ -220,11 +231,14 @@ bool ImGui_ImplGlfwGL3_CreateDeviceObjects()
glVertexAttribPointer(g_AttribLocationUV, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)OFFSETOF(ImDrawVert, uv));
glVertexAttribPointer(g_AttribLocationColor, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert), (GLvoid*)OFFSETOF(ImDrawVert, col));
#undef OFFSETOF
glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
ImGui_ImplGlfwGL3_CreateFontsTexture();
// Restore modified GL state
glBindTexture(GL_TEXTURE_2D, last_texture);
glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
glBindVertexArray(last_vertex_array);
return true;
}