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Add OpenGlOptions.AntiAliasingSamples : default is 8 (improves text r…
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…endering on windows)
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@pthom
pthom committed Jul 6, 2024
1 parent 19af0b4 commit 3abdfa8
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Showing 4 changed files with 97 additions and 30 deletions.
23 changes: 14 additions & 9 deletions hello_imgui_example.ini
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Original file line number Diff line number Diff line change
Expand Up @@ -47,12 +47,17 @@
; UseCoreProfile = true
; UseForwardCompat = false

; `AntiAliasingSamples`
; If not zero, this value will be used to reduce the number of samples used for anti-aliasing.
; This is used only when running with Glfw + OpenGL (which is the default)
; Notes:
; - by default, we query the maximum number of samples supported by the hardwareand we use this value
; - if you set this value to a non-zero value, it will be used instead of the maximum value
; (except if it is greater than the maximum value, in which case a warning will be issued)
; (it will be via `glfwWindowHint(GLFW_SAMPLES, AntiAliasingSamples);`)
; AntiAliasingSamples=16
; `AntiAliasingSamples`
; If > 0, this value will be used to set the number of samples used for anti-aliasing.
; This is used only when running with Glfw + OpenGL (which is the default)
; Notes:
; - we query the maximum number of samples supported by the hardware, via glGetIntegerv(GL_MAX_SAMPLES)
; - if you set this value to a non-zero value, it will be used instead of the default value of 8
; (except if it is greater than the maximum supported value, in which case a warning will be issued)
; - if you set this value to 0, anti-aliasing will be disabled
;
; AntiAliasingSamples has a strong impact on the quality of the text rendering
; - 0: no anti-aliasing
; - 8: optimal
; - 16: optimal if using imgui-node-editor and you want to render very small text when unzooming
;AntiAliasingSamples=8
19 changes: 6 additions & 13 deletions src/hello_imgui/internal/backend_impls/abstract_runner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -253,18 +253,8 @@ void AbstractRunner::ReadOpenGlOptions()
// you may set them manually:
// (1) Either by setting them programmatically in your application
// (set their values in `runnerParams.rendererBackendOptions.openGlOptions`)
// (2) Either by setting them in a `hello_imgui.ini` file in the current folder, or any of its parent folders.
// (this is useful when you want to set them for a specific app or set of apps, without modifying the app code)
// Note: if several methods are used, the order of priority is (1) > (2)
//
// Example content of a hello_imgui.ini file:
// ------------------------------
// [OpenGlOptions]
// GlslVersion = 130
// MajorVersion = 3
// MinorVersion = 2
// UseCoreProfile = true
// UseForwardCompat = false
// (2) Either by setting them in a `hello_imgui.ini` file. See hello_imgui/hello_imgui_example.ini for more info
// Note: if several methods are used, the order of priority is (1) > (2)

// If options specified by the program, do not read them.
if (params.rendererBackendOptions.openGlOptions.has_value())
Expand All @@ -277,8 +267,9 @@ void AbstractRunner::ReadOpenGlOptions()
auto useCoreProfile = HelloImGuiIniAnyParentFolder::readBoolValue(openGlSection, "UseCoreProfile");
auto useForwardCompat = HelloImGuiIniAnyParentFolder::readBoolValue(openGlSection, "UseForwardCompat");
auto glslVersion = HelloImGuiIniAnyParentFolder::readStringValue(openGlSection, "GlslVersion");
auto antiAliasingSamples = HelloImGuiIniAnyParentFolder::readIntValue(openGlSection, "AntiAliasingSamples");

bool isAnySettingsSpecified = majorVersion.has_value() || minorVersion.has_value() || useCoreProfile.has_value() || useForwardCompat.has_value() || glslVersion.has_value();
bool isAnySettingsSpecified = majorVersion.has_value() || minorVersion.has_value() || useCoreProfile.has_value() || useForwardCompat.has_value() || glslVersion.has_value() || antiAliasingSamples.has_value();

if (isAnySettingsSpecified)
{
Expand All @@ -294,6 +285,8 @@ void AbstractRunner::ReadOpenGlOptions()
openGlOptions.UseForwardCompat = useForwardCompat.value();
if (glslVersion.has_value())
openGlOptions.GlslVersion = glslVersion.value();
if (antiAliasingSamples.has_value())
openGlOptions.AntiAliasingSamples = antiAliasingSamples.value();
}

}
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61 changes: 61 additions & 0 deletions src/hello_imgui/internal/backend_impls/opengl_setup_helper/opengl_setup_glfw.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,63 @@

namespace HelloImGui { namespace BackendApi
{
static int QueryMaxAntiAliasingSamples()
{
// First create a dummy window to make OpenGL context current
GLFWwindow* dummyWindow = []
{
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
return glfwCreateWindow(64, 32, "Dummy", NULL, NULL);
}();

if (!dummyWindow)
IM_ASSERT(false && "Failed to create temporary window.");
glfwMakeContextCurrent(dummyWindow);

// Init OpenGL loader
OpenGlSetupGlfw openGlSetupGlfw;
openGlSetupGlfw.InitGlLoader();

GLint maxSamples;
glGetIntegerv(GL_MAX_SAMPLES, &maxSamples);

glfwDestroyWindow(dummyWindow);

return maxSamples;
}

static void ApplyAntiAliasingSamples(OpenGlOptions& openGlOptions)
{
int userQuerySamples = openGlOptions.AntiAliasingSamples;
int maxGpuSamples = QueryMaxAntiAliasingSamples();
int effectiveSamples = 8;

if (effectiveSamples > maxGpuSamples)
effectiveSamples = maxGpuSamples;

if (userQuerySamples == 0)
effectiveSamples = 0;
else if (userQuerySamples > 0)
{
if (userQuerySamples > maxGpuSamples)
fprintf(stderr, "Warning: user requested %d samples, but GPU supports only %d samples. Using %d samples instead.\n", userQuerySamples, maxGpuSamples, maxGpuSamples);
if (userQuerySamples <= maxGpuSamples)
effectiveSamples = userQuerySamples;
}

if (effectiveSamples > 0)
{
glEnable(GL_MULTISAMPLE);
glfwWindowHint(GLFW_SAMPLES, effectiveSamples);
}
else
{
glfwWindowHint(GLFW_SAMPLES, 0);
}
}

static void ApplyOpenGlOptions(OpenGlOptions& openGlOptions)
{
Expand All @@ -18,6 +75,8 @@ namespace HelloImGui { namespace BackendApi
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
if (openGlOptions.UseForwardCompat)
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

ApplyAntiAliasingSamples(openGlOptions);
}

static OpenGlOptions MakeOpenGlOptions()
Expand All @@ -28,6 +87,8 @@ namespace HelloImGui { namespace BackendApi

OpenGlOptions openGlOptions;

openGlOptions.AntiAliasingSamples = -1; // -1 <=> not set, will use the default value of 8

//
// Compute MajorVersion, MinorVersion, UseCoreProfile, UseForwardCompat
//
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24 changes: 16 additions & 8 deletions src/hello_imgui/renderer_backend_options.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,16 +25,9 @@ namespace HelloImGui
// (set their values in `runnerParams.rendererBackendOptions.openGlOptions`)
// (2) Either by setting them in a `hello_imgui.ini` file in the current folder, or any of its parent folders.
// (this is useful when you want to set them for a specific app or set of apps, without modifying the app code)
// See hello_imgui/hello_imgui_example.ini for an example of such a file.
// Note: if several methods are used, the order of priority is (1) > (2)
//
// Example content of a ini file:
// ------------------------------
// [OpenGlOptions]
// GlslVersion = 130
// MajorVersion = 3
// MinorVersion = 2
// UseCoreProfile = true
// UseForwardCompat = false
struct OpenGlOptions
{
// Could be for example:
Expand All @@ -51,6 +44,21 @@ struct OpenGlOptions
bool UseCoreProfile = true;
// OpenGL Forward Compatibility (required on macOS)
bool UseForwardCompat = true;

// `AntiAliasingSamples`
// If > 0, this value will be used to set the number of samples used for anti-aliasing.
// This is used only when running with Glfw + OpenGL (which is the default)
// Notes:
// - we query the maximum number of samples supported by the hardware, via glGetIntegerv(GL_MAX_SAMPLES)
// - if you set this value to a non-zero value, it will be used instead of the default value of 8
// (except if it is greater than the maximum supported value, in which case a warning will be issued)
// - if you set this value to 0, anti-aliasing will be disabled
//
// AntiAliasingSamples has a strong impact on the quality of the text rendering
// - 0: no anti-aliasing
// - 8: optimal
// - 16: optimal if using imgui-node-editor and you want to render very small text when unzooming
int AntiAliasingSamples = -1; // -1 <=> not set (will use the default value of 8)
};

// @@md
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