Merge pull request #1400 from wolfpld/slomp/gl-example

adding OpenGL example (spinning triangle)

examples/opengl/triangle/CMakeLists.txt

@@ -0,0 +1,83 @@
+# CMakeLists.txt — OpenGL spinning triangle demo
+#
+#   macOS:
+#     cmake -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -B build/ninja .
+#     cmake --build build/ninja
+#
+#   Linux (requires libsdl3-dev libgl1-mesa-dev):
+#     cmake -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -B build/ninja .
+#     cmake --build build/ninja
+#
+#   Windows:
+#     cmake -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -B build/ninja .
+#     cmake --build build/ninja
+
+cmake_minimum_required(VERSION 3.16)
+project(gl_spinning_triangle LANGUAGES C CXX)
+
+# ---------------------------------------------------------------------------
+# Tracy root — defaults to three directories above this CMakeLists.txt.
+# ---------------------------------------------------------------------------
+set(TRACY_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../..")
+option(TRACY_ENABLE                  "Enable Tracy profiling"                    ON)
+
+# ---------------------------------------------------------------------------
+# Platform — SDL3 (cross-platform windowing, must be installed on the system)
+# ---------------------------------------------------------------------------
+find_package(SDL3 REQUIRED)
+
+# ---------------------------------------------------------------------------
+# GL extension loader — GLEW (Windows + Linux, fetched automatically)
+# ---------------------------------------------------------------------------
+if(NOT APPLE)
+    include(FetchContent)
+    set(glew-cmake_BUILD_SHARED OFF CACHE BOOL "" FORCE)
+    set(ONLY_LIBS               ON  CACHE BOOL "" FORCE)
+    FetchContent_Declare(glew
+        GIT_REPOSITORY https://github.com/Perlmint/glew-cmake.git
+        GIT_TAG        master   # pin to a specific commit for reproducible builds
+        GIT_SHALLOW    TRUE
+    )
+    FetchContent_MakeAvailable(glew)
+endif()
+
+set(PLATFORM_SOURCES  platform/platform_sdl3.cpp)
+
+if(APPLE)
+    set(PLATFORM_LIBS SDL3::SDL3 "-framework OpenGL")
+elseif(WIN32)
+    set(PLATFORM_LIBS SDL3::SDL3 opengl32 libglew_static)
+else()
+    set(PLATFORM_LIBS SDL3::SDL3 GL libglew_static)
+endif()
+
+# ---------------------------------------------------------------------------
+# Target
+# ---------------------------------------------------------------------------
+add_executable(gl_spinning_triangle
+    spinning_triangle.cpp
+    "${TRACY_DIR}/public/TracyClient.cpp"
+    ${PLATFORM_SOURCES}
+)
+
+# Suppress upstream warnings from TracyClient.cpp
+if(MSVC)
+    set_source_files_properties("${TRACY_DIR}/public/TracyClient.cpp"
+        PROPERTIES COMPILE_FLAGS "/w"
+    )
+else()
+    set_source_files_properties("${TRACY_DIR}/public/TracyClient.cpp"
+        PROPERTIES COMPILE_FLAGS "-w"
+    )
+endif()
+
+target_compile_features(gl_spinning_triangle PRIVATE cxx_std_17)
+
+if(TRACY_ENABLE)
+    target_compile_definitions(gl_spinning_triangle PRIVATE TRACY_ENABLE)
+endif()
+
+target_include_directories(gl_spinning_triangle PRIVATE
+    "${TRACY_DIR}/public"
+)
+target_link_libraries(gl_spinning_triangle PRIVATE ${PLATFORM_LIBS})

examples/opengl/triangle/platform/platform.h

@@ -0,0 +1,37 @@
+// platform.h — interface between platform-agnostic code and platform backends
+//
+// Each platform_*.mm / platform_*.cpp file implements these four functions.
+// Exactly one backend must be linked into the final binary.
+
+#pragma once
+
+#ifdef __APPLE__
+#  include <OpenGL/gl3.h>
+#else
+#  include <GL/glew.h>
+#endif
+
+// Initialize the windowing system, create a window, and make an OpenGL 3.3
+// Core Profile context current on the calling thread.
+// Returns true on success.
+bool platformInit(int width, int height, const char* title);
+
+// Load OpenGL function pointers (no-op on macOS where the framework exports them directly).
+// Must be called after platformInit() while the GL context is current.
+// Returns true on success.
+bool platformInitGL();
+
+// Elapsed wall-clock time in seconds since platformInit().
+double platformGetTime();
+
+// Swap front and back buffers (present the rendered frame).
+void platformSwapBuffers();
+
+// Pixel scaling factor relative to the logical window size (1.0 on non-HiDPI displays).
+// Must be called after platformInit().
+void platformGetPixelDensityScale(float* x, float* y);
+
+// Enter the platform event/render loop.
+// Calls render() each frame at ~60 fps.
+// Calls shutdown() exactly once before returning.
+void platformRunLoop(void (*render)(), void (*shutdown)());

examples/opengl/triangle/platform/platform_sdl3.cpp

@@ -0,0 +1,85 @@
+// platform_sdl3.cpp — SDL3 windowing backend (cross-platform)
+#include "platform.h"   // GL headers first (gl3.h / glew.h) so SDL sees guards set
+
+#define SDL_MAIN_HANDLED    // we don't want SDL_main
+#include <SDL3/SDL.h>
+
+#include <chrono>
+#include <cstdio>
+
+static SDL_Window*   sWin = nullptr;
+static SDL_GLContext sCtx = nullptr;
+static std::chrono::steady_clock::time_point sStartTime;
+
+bool platformInit(int width, int height, const char* title) {
+    if (!SDL_Init(SDL_INIT_VIDEO)) {
+        fprintf(stderr, "ERROR: SDL_Init failed: %s\n", SDL_GetError());
+        return false;
+    }
+
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+
+    sWin = SDL_CreateWindow(title, width, height, SDL_WINDOW_OPENGL);
+    if (!sWin) {
+        fprintf(stderr, "ERROR: SDL_CreateWindow failed: %s\n", SDL_GetError());
+        SDL_Quit();
+        return false;
+    }
+    SDL_SetWindowPosition(sWin, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED);
+
+    sCtx = SDL_GL_CreateContext(sWin);
+    if (!sCtx) {
+        fprintf(stderr, "ERROR: SDL_GL_CreateContext failed: %s\n", SDL_GetError());
+        SDL_DestroyWindow(sWin);
+        SDL_Quit();
+        return false;
+    }
+
+    SDL_GL_SetSwapInterval(1);
+    sStartTime = std::chrono::steady_clock::now();
+    return true;
+}
+
+bool platformInitGL() {
+#ifndef __APPLE__
+    glewExperimental = GL_TRUE;
+    if (glewInit() != GLEW_OK) {
+        fprintf(stderr, "Failed to initialize GLEW\n");
+        return false;
+    }
+#endif
+    return true;
+}
+
+double platformGetTime() {
+    return std::chrono::duration<double>(
+        std::chrono::steady_clock::now() - sStartTime).count();
+}
+
+void platformSwapBuffers() { SDL_GL_SwapWindow(sWin); }
+
+void platformGetPixelDensityScale(float* x, float* y) {
+    int pw, ph, ww, wh;
+    SDL_GetWindowSizeInPixels(sWin, &pw, &ph);
+    SDL_GetWindowSize(sWin, &ww, &wh);
+    *x = (ww > 0) ? (float)pw / (float)ww : 1.0f;
+    *y = (wh > 0) ? (float)ph / (float)wh : 1.0f;
+}
+
+void platformRunLoop(void (*render)(), void (*shutdown)()) {
+    bool running = true;
+    while (running) {
+        SDL_Event e;
+        while (SDL_PollEvent(&e)) {
+            if (e.type == SDL_EVENT_QUIT) running = false;
+            if (e.type == SDL_EVENT_KEY_DOWN && e.key.key == SDLK_ESCAPE) running = false;
+        }
+        if (running) render();
+    }
+    shutdown();
+    SDL_GL_DestroyContext(sCtx);
+    SDL_DestroyWindow(sWin);
+    SDL_Quit();
+}

examples/opengl/triangle/spinning_triangle.cpp

@@ -0,0 +1,145 @@
+// spinning_triangle.cpp — OpenGL spinning triangle demo with Tracy GPU profiling.
+
+#ifdef __APPLE__
+// NOTE: OpenGL is only available on MacOS (no iOS support)
+// Including and using anything related to OpenGL on Apple (like <OpenGL/gl3.h>)
+// will emit deprecation warnings, unless GL_SILENCE_DEPRECATION is defined
+#define GL_SILENCE_DEPRECATION
+// NOTE: TracyOpenGL.hpp will not work as expected even on Apple devices that
+// support OpenGL, because the OpenGL drivers do not implement ARB_timer_query
+// properly (querying GL_TIMESTAMP always resolves to 0). TracyOpenGL.hpp will
+// emit a compiler warning, and a Tracy message to the trace/profiler, but the
+// program will still run.
+#endif
+
+#include "platform/platform.h"  // also includes OpenGL headers
+
+#include <tracy/Tracy.hpp>
+
+// NOTE: opt-in toggle for periodic recalibrations during Collect()
+#define TRACY_OPENGL_AUTO_CALIBRATION
+#include <tracy/TracyOpenGL.hpp>
+
+static const int kWidth  = 800;
+static const int kHeight = 600;
+
+static GLuint gProgram  = 0;
+static GLuint gVao      = 0;
+static GLint  gAngleLoc = -1;
+
+// Vertex colors and positions are baked in; rotation is driven by a uniform.
+static const char* kVertSrc = R"(
+#version 150 core
+uniform float uAngle;
+const vec2 kPos[3] = vec2[3](
+    vec2( 0.0,    0.5  ),
+    vec2(-0.433, -0.25 ),
+    vec2( 0.433, -0.25 )
+);
+const vec3 kCol[3] = vec3[3](
+    vec3(1.0, 0.0, 0.0),
+    vec3(0.0, 1.0, 0.0),
+    vec3(0.0, 0.0, 1.0)
+);
+out vec3 vColor;
+void main() {
+    float c = cos(uAngle);
+    float s = sin(uAngle);
+    vec2  p = kPos[gl_VertexID];
+    gl_Position = vec4(p.x*c - p.y*s, p.x*s + p.y*c, 0.0, 1.0);
+    vColor = kCol[gl_VertexID];
+}
+)";
+
+static const char* kFragSrc = R"(
+#version 150 core
+in  vec3 vColor;
+out vec4 fragColor;
+void main() { fragColor = vec4(vColor, 1.0); }
+)";
+
+static GLuint compileShader(GLenum type, const char* src) {
+    GLuint s = glCreateShader(type);
+    glShaderSource(s, 1, &src, nullptr);
+    glCompileShader(s);
+    GLint ok = 0;
+    glGetShaderiv(s, GL_COMPILE_STATUS, &ok);
+    if (!ok) {
+        char log[512];
+        glGetShaderInfoLog(s, sizeof(log), nullptr, log);
+        fprintf(stderr, "Shader compile error: %s\n", log);
+        glDeleteShader(s);
+        return 0;
+    }
+    return s;
+}
+
+static int initGL() {
+    if (!platformInitGL()) return 1;
+
+    TracyGpuContext;
+    TracyGpuContextName("OpenGL", 6);
+
+    GLuint vert = compileShader(GL_VERTEX_SHADER,   kVertSrc);
+    GLuint frag = compileShader(GL_FRAGMENT_SHADER, kFragSrc);
+    if (!vert || !frag) return 1;
+
+    gProgram = glCreateProgram();
+    glAttachShader(gProgram, vert);
+    glAttachShader(gProgram, frag);
+    glLinkProgram(gProgram);
+    glDeleteShader(vert);
+    glDeleteShader(frag);
+
+    GLint ok = 0;
+    glGetProgramiv(gProgram, GL_LINK_STATUS, &ok);
+    if (!ok) {
+        char log[512];
+        glGetProgramInfoLog(gProgram, sizeof(log), nullptr, log);
+        fprintf(stderr, "Program link error: %s\n", log);
+        return 1;
+    }
+
+    gAngleLoc = glGetUniformLocation(gProgram, "uAngle");
+
+    // Core profile requires a bound VAO even with no vertex attributes.
+    glGenVertexArrays(1, &gVao);
+    glBindVertexArray(gVao);
+
+    glClearColor(0.05f, 0.05f, 0.08f, 1.0f);
+    float scaleX, scaleY;
+    platformGetPixelDensityScale(&scaleX, &scaleY);
+    glViewport(0, 0, (int)(kWidth * scaleX), (int)(kHeight * scaleY));
+    return 0;
+}
+
+static void renderFrame() {
+    ZoneScoped;
+
+    glClear(GL_COLOR_BUFFER_BIT);
+    glUseProgram(gProgram);
+
+    {
+        TracyGpuZone("triangle draw");
+        glUniform1f(gAngleLoc, (float)platformGetTime());
+        glDrawArrays(GL_TRIANGLES, 0, 3);
+    }
+
+    platformSwapBuffers();
+    TracyGpuCollect;
+}
+
+static void shutdown() {
+    fprintf(stderr, "application is shutting down...\n");
+    glDeleteVertexArrays(1, &gVao);
+    glDeleteProgram(gProgram);
+}
+
+int main() {
+    if (!platformInit(kWidth, kHeight, "OpenGL Spinning Triangle"))
+        return 1;
+    if (initGL() != 0)
+        return 2;
+    platformRunLoop(renderFrame, shutdown);
+    return 0;
+}

public/tracy/TracyOpenGL.hpp

@@ -1,7 +1,12 @@
 #ifndef __TRACYOPENGL_HPP__
 #define __TRACYOPENGL_HPP__
 
-#if !defined TRACY_ENABLE || defined __APPLE__
+#ifdef __APPLE__
+#define TRACY_OPENGL_DISABLE
+#warning "OpenGL timestamps are unreliable on Apple devices that still run OpenGL."
+#endif
+
+#if !defined TRACY_ENABLE || defined TRACY_OPENGL_DISABLE
 
 #define TracyGpuContext
 #define TracyGpuContextName(x,y)
@@ -98,17 +103,25 @@ public:
         , m_head( 0 )
         , m_tail( 0 )
     {
+        ZoneScopedC( Color::Red4 );
+
         assert( m_context != 255 );
 
-        glGenQueries( QueryCount, m_query );
+        GLint bits;
+        glGetQueryiv( GL_TIMESTAMP, GL_QUERY_COUNTER_BITS, &bits );
+        if( bits == 0 )
+        {
+            // all timestamp queries would resolve to 0 (and produce 0ns GPU zones).
+            // (this is the case for many TBDR GPUs, including Apple Silicon)
+            Profiler::LogString( MessageSourceType::Tracy, MessageSeverity::Warning, Color::Tomato, 0,
+                "OpenGL driver does not implement GL_TIMESTAMP precision." );
+        }
+        assert( bits > 0 );
 
         int64_t tgpu;
         glGetInteger64v( GL_TIMESTAMP, &tgpu );
         int64_t tcpu = Profiler::GetTime();
 
-        GLint bits;
-        glGetQueryiv( GL_TIMESTAMP, GL_QUERY_COUNTER_BITS, &bits );
-
 #ifdef TRACY_OPENGL_AUTO_CALIBRATION
         // The anchor above is never refreshed; advertise calibration and emit periodic
         // GpuCalibration events to correct CPU/GPU drift (see Recalibrate). Opt-in,
@@ -117,6 +130,8 @@ public:
         m_prevCalibration = GetHostTimeNs();
 #endif
 
+        glGenQueries( QueryCount, m_query );
+
         const float period = 1.f;
         const auto thread = GetThreadHandle();
         TracyLfqPrepare( QueueType::GpuNewContext );