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Merged
bridgecommand merged 4 commits into from
Feb 22, 2026
+125 −42
Merged

Apply anti-aliasing in VR mode (OpenXR) #91

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58151eb
WIP implementing MSAA for VR (OpenXR)
bridgecommand Feb 19, 2026
d134bc1
Now basically working, needs some tidying up.
bridgecommand Feb 19, 2026
279dba4
Tidying up
bridgecommand Feb 20, 2026
43d2cb7
Remove commented out lines
bridgecommand Feb 20, 2026
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157 changes: 115 additions & 42 deletions src/VRInterface.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -198,6 +198,19 @@ int VRInterface::load(SimulationModel* model) {
std::cout << "glDeleteRenderbuffers not available" << std::endl;
return 1;
}

glRenderbufferStorageMultisample = (PFNGLRENDERBUFFERSTORAGEMULTISAMPLEPROC)wglGetProcAddress("glRenderbufferStorageMultisample");
if (glRenderbufferStorageMultisample == 0) {
std::cout << "glRenderbufferStorageMultisample not available" << std::endl;
return 1;
}

glBlitFramebuffer = (PFNGLBLITFRAMEBUFFERPROC)wglGetProcAddress("glBlitFramebuffer");
if (glBlitFramebuffer == 0) {
std::cout << "glBlitFramebuffer not available" << std::endl;
return 1;
}

#elif defined __linux__
// glXGetProcAddress never returns Null, so no point in checking
glGenFramebuffers = (PFNGLGENFRAMEBUFFERSPROC)glXGetProcAddress((const GLubyte *)"glGenFramebuffers");
Expand All @@ -210,6 +223,8 @@ int VRInterface::load(SimulationModel* model) {
glFramebufferRenderbuffer = (PFNGLFRAMEBUFFERRENDERBUFFERPROC)glXGetProcAddress((const GLubyte *)"glFramebufferRenderbuffer");
glDeleteFramebuffers = (PFNGLDELETEFRAMEBUFFERSPROC)glXGetProcAddress((const GLubyte *)"glDeleteFramebuffers");
glDeleteRenderbuffers = (PFNGLDELETERENDERBUFFERSPROC)glXGetProcAddress((const GLubyte *)"glDeleteRenderbuffers");
glRenderbufferStorageMultisample = (PFNGLRENDERBUFFERSTORAGEMULTISAMPLEPROC)glXGetProcAddress((const GLubyte*)"glRenderbufferStorageMultisample");
glBlitFramebuffer = (PFNGLBLITFRAMEBUFFERPROC)glXGetProcAddress((const GLubyte*)"glBlitFramebuffer");
#endif

// Changing to HANDHELD_DISPLAY or a future form factor may work, but has not been tested.
Expand All @@ -231,7 +246,6 @@ int VRInterface::load(SimulationModel* model) {

// each graphics API requires the use of a specialized struct
#ifdef _WIN32
//XrGraphicsBindingOpenGLWin32KHR graphics_binding_gl = { 0 };
XrGraphicsBindingOpenGLWin32KHR graphics_binding_gl;
graphics_binding_gl.type = XR_TYPE_UNKNOWN;
graphics_binding_gl.next = NULL;
Expand Down Expand Up @@ -316,7 +330,6 @@ int VRInterface::load(SimulationModel* model) {
return 1;
}

//XrExtensionProperties* ext_props = malloc(sizeof(XrExtensionProperties) * ext_count);
XrExtensionProperties* ext_props = new XrExtensionProperties[ext_count];

for (uint16_t i = 0; i < ext_count; i++) {
Expand Down Expand Up @@ -344,7 +357,6 @@ int VRInterface::load(SimulationModel* model) {
depth.supported = true;
}
}
//free(ext_props);
delete[] ext_props;

// A graphics extension like OpenGL is required to draw anything in VR
Expand Down Expand Up @@ -412,7 +424,6 @@ int VRInterface::load(SimulationModel* model) {
if (!xr_check(instance, result, "Failed to get view configuration view count!"))
return 1;

//viewconfig_views = malloc(sizeof(XrViewConfigurationView) * view_count);
viewconfig_views = new XrViewConfigurationView[view_count];

for (uint32_t i = 0; i < view_count; i++) {
Expand Down Expand Up @@ -506,11 +517,8 @@ int VRInterface::load(SimulationModel* model) {
// --- Create swapchain for main VR rendering

// In the frame loop we render into OpenGL textures we receive from the runtime here.
//swapchains = malloc(sizeof(XrSwapchain) * view_count);
swapchains = new XrSwapchain[view_count];
//swapchain_lengths = malloc(sizeof(uint32_t) * view_count);
swapchain_lengths = new uint32_t[view_count];
//images = malloc(sizeof(XrSwapchainImageOpenGLKHR*) * view_count);
images = new XrSwapchainImageOpenGLKHR*[view_count];
for (uint32_t i = 0; i < view_count; i++) {
XrSwapchainCreateInfo swapchain_create_info;
Expand All @@ -536,7 +544,6 @@ int VRInterface::load(SimulationModel* model) {
if (!xr_check(instance, result, "Failed to enumerate swapchains"))
return 1;

//images[i] = malloc(sizeof(XrSwapchainImageOpenGLKHR) * swapchain_lengths[i]);
images[i] = new XrSwapchainImageOpenGLKHR[swapchain_lengths[i]];
for (uint32_t j = 0; j < swapchain_lengths[i]; j++) {
images[i][j].type = XR_TYPE_SWAPCHAIN_IMAGE_OPENGL_KHR;
Expand All @@ -551,19 +558,89 @@ int VRInterface::load(SimulationModel* model) {
// Store image width and height, assumed to be same for both views
swapchainImageWidth = swapchain_create_info.width;
swapchainImageHeight = swapchain_create_info.height;
}

// Create framebuffers
framebuffers = new GLuint * [view_count];
depthbuffers = new GLuint * [view_count];
for (uint32_t i = 0; i < view_count; i++) {
framebuffers[i] = new GLuint[swapchain_lengths[i]];
depthbuffers[i] = new GLuint[swapchain_lengths[i]];
}

for (uint32_t i = 0; i < view_count; i++) {
// ---------------------------------------------------------
// Create per-swapchain-image FBO (attach once!)
// ---------------------------------------------------------
for (uint32_t j = 0; j < swapchain_lengths[i]; ++j)
{
glGenFramebuffers(1, &framebuffers[i][j]);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffers[i][j]);

glFramebufferTexture2D(
GL_FRAMEBUFFER,
GL_COLOR_ATTACHMENT0,
GL_TEXTURE_2D,
images[i][j].image,
0
);

if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
std::cerr << "Swapchain FBO incomplete!" << std::endl;
}
}

glBindFramebuffer(GL_FRAMEBUFFER, 0);

// ---------------------------------------------------------
// Create MSAA framebuffer for this eye
// ---------------------------------------------------------
int width = viewconfig_views[i].recommendedImageRectWidth;
int height = viewconfig_views[i].recommendedImageRectHeight;

glGenFramebuffers(1, &msaaFBO[i]);
glBindFramebuffer(GL_FRAMEBUFFER, msaaFBO[i]);

// --- Multisample color ---
glGenRenderbuffers(1, &msaaColor[i]);
glBindRenderbuffer(GL_RENDERBUFFER, msaaColor[i]);
glRenderbufferStorageMultisample(
GL_RENDERBUFFER,
MSAA_SAMPLES,
color_format,
width,
height
);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
GL_RENDERBUFFER, msaaColor[i]);

// --- Multisample depth ---
glGenRenderbuffers(1, &msaaDepth[i]);
glBindRenderbuffer(GL_RENDERBUFFER, msaaDepth[i]);
glRenderbufferStorageMultisample(
GL_RENDERBUFFER,
MSAA_SAMPLES,
GL_DEPTH24_STENCIL8,
width,
height
);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
GL_RENDERBUFFER, msaaDepth[i]);

if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
std::cerr << "MSAA FBO incomplete!" << std::endl;
}

glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

// Do not allocate these every frame to save some resources
//views = (XrView*)malloc(sizeof(XrView) * view_count);
views = new XrView[view_count];
for (uint32_t i = 0; i < view_count; i++) {
views[i].type = XR_TYPE_VIEW;
views[i].next = NULL;
}

//projection_views = (XrCompositionLayerProjectionView*)malloc(
// sizeof(XrCompositionLayerProjectionView) * view_count);
projection_views = new XrCompositionLayerProjectionView[view_count];
for (uint32_t i = 0; i < view_count; i++) {
projection_views[i].type = XR_TYPE_COMPOSITION_LAYER_PROJECTION_VIEW;
Expand All @@ -581,15 +658,7 @@ int VRInterface::load(SimulationModel* model) {
// projection_views[i].{pose, fov} have to be filled every frame in frame loop
};

// Create framebuffers
framebuffers = new GLuint* [view_count];
depthbuffers = new GLuint * [view_count];
for (uint32_t i = 0; i < view_count; i++) {
framebuffers[i] = new GLuint[swapchain_lengths[i]];
depthbuffers[i] = new GLuint[swapchain_lengths[i]];
glGenFramebuffers(swapchain_lengths[i], framebuffers[i]);
glGenRenderbuffers(swapchain_lengths[i], depthbuffers[i]);
}


// Set up controllers
// --- Set up input (actions)
Expand Down Expand Up @@ -1347,29 +1416,34 @@ int VRInterface::update() {
int w = viewconfig_views[i].recommendedImageRectWidth;
int h = viewconfig_views[i].recommendedImageRectHeight;

// Render into swapchain images here (for left or right eye), into images[i][acquired_index].image
glBindFramebuffer(GL_FRAMEBUFFER, framebuffers[i][acquired_index]);
// ---------------------------------------------------------
// 1) Render scene into MSAA buffer
// ---------------------------------------------------------
glBindFramebuffer(GL_FRAMEBUFFER, msaaFBO[i]);

glBindRenderbuffer(GL_RENDERBUFFER, depthbuffers[i][acquired_index]);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, w, h);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthbuffers[1][acquired_index]);

glViewport(0, 0, w, h);
glScissor(0, 0, w, h);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, images[i][acquired_index].image, 0);
glClearColor(0.0f, 0.0f, 0.2f, 1.0f);

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// Check
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
std::cout << "glCheckFramebufferStatus: " << glCheckFramebufferStatus(GL_FRAMEBUFFER) << std::endl;
}

// Render
smgr->drawAll();

// Return to framebuffer
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// ---------------------------------------------------------
// 2) Resolve MSAA -> swapchain image
// ---------------------------------------------------------

glBindFramebuffer(GL_READ_FRAMEBUFFER, msaaFBO[i]);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER,
framebuffers[i][acquired_index]);

glBlitFramebuffer(
0, 0,
viewconfig_views[i].recommendedImageRectWidth,
viewconfig_views[i].recommendedImageRectHeight,
0, 0,
viewconfig_views[i].recommendedImageRectWidth,
viewconfig_views[i].recommendedImageRectHeight,
GL_COLOR_BUFFER_BIT,
GL_NEAREST
);

XrSwapchainImageReleaseInfo release_info;
release_info.type = XR_TYPE_SWAPCHAIN_IMAGE_RELEASE_INFO;
Expand Down Expand Up @@ -1412,6 +1486,9 @@ int VRInterface::update() {
if (!xr_check(instance, result, "failed to end frame!"))
return 1;

// Return to normal framebuffer
glBindFramebuffer(GL_FRAMEBUFFER, 0);

// Do ray/mesh intersection here if 'select' is active and HUD is shown
if (showHUD) {
if (selectState[HAND_LEFT_INDEX] || selectState[HAND_RIGHT_INDEX]) {
Expand Down Expand Up @@ -1712,7 +1789,6 @@ void VRInterface::print_api_layers()
if (count == 0)
return;

//XrApiLayerProperties* props = malloc(count * sizeof(XrApiLayerProperties));
XrApiLayerProperties* props = new XrApiLayerProperties[count];
for (uint32_t i = 0; i < count; i++) {
props[i].type = XR_TYPE_API_LAYER_PROPERTIES;
Expand All @@ -1728,7 +1804,6 @@ void VRInterface::print_api_layers()
printf("\t%s v%d: %s\n", props[i].layerName, props[i].layerVersion, props[i].description);
}

//free(props)
delete[] props;
#else
std::cout << "VR interface not implemented" << std::endl;
Expand Down Expand Up @@ -1809,7 +1884,6 @@ int64_t VRInterface::get_swapchain_format(XrInstance instance,
return -1;

printf("Runtime supports %d swapchain formats\n", swapchain_format_count);
//int64_t* swapchain_formats = malloc(sizeof(int64_t) * swapchain_format_count);
int64_t* swapchain_formats = new int64_t[swapchain_format_count];
result = xrEnumerateSwapchainFormats(session, swapchain_format_count, &swapchain_format_count,
swapchain_formats);
Expand All @@ -1830,7 +1904,6 @@ int64_t VRInterface::get_swapchain_format(XrInstance instance,
printf("Falling back to non preferred swapchain format %#lx\n", chosen_format);
}

//free(swapchain_formats);
delete[] swapchain_formats;

return chosen_format;
Expand Down
10 changes: 10 additions & 0 deletions src/VRInterface.hpp
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -133,6 +133,8 @@ class VRInterface {
PFNGLFRAMEBUFFERRENDERBUFFERPROC glFramebufferRenderbuffer;
PFNGLDELETEFRAMEBUFFERSPROC glDeleteFramebuffers;
PFNGLDELETERENDERBUFFERSPROC glDeleteRenderbuffers;
PFNGLRENDERBUFFERSTORAGEMULTISAMPLEPROC glRenderbufferStorageMultisample;
PFNGLBLITFRAMEBUFFERPROC glBlitFramebuffer;
#endif

bool quit_mainloop;
Expand Down Expand Up @@ -181,6 +183,14 @@ class VRInterface {
bool previousSelectState[HAND_COUNT];
irr::s32 raySelectScreenX;
irr::s32 raySelectScreenY;

// --- MSAA ---
static const int MSAA_SAMPLES = 4;

GLuint msaaFBO[2] = { 0, 0 };
GLuint msaaColor[2] = { 0, 0 };
GLuint msaaDepth[2] = { 0, 0 };

};

#endif
Expand Down