trying some shader stuff, but segfaults

Makefile

@@ -21,10 +21,10 @@ SOURCES += $(wildcard $(IMGUI_DIR)/*.cpp)
 SOURCES += $(wildcard $(IMGUI_DIR)/backends/*.cpp)
 OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
 UNAME_S := $(shell uname -s)
-LINUX_GL_LIBS = -lGL
+LINUX_GL_LIBS = -lGL -lGLEW
 
 CXXFLAGS = -std=c++20 -I$(IMGUI_DIR) -I$(IMGUI_DIR)/backends
-CXXFLAGS += -g -DIMGUI_DEFINE_MATH_OPERATORS -Ofast
+CXXFLAGS += -g -DIMGUI_DEFINE_MATH_OPERATORS 
 LIBS =
 
 ##---------------------------------------------------------------------
@@ -52,7 +52,7 @@ endif
 
 ifeq ($(UNAME_S), Darwin) #APPLE
 	ECHO_MESSAGE = "Mac OS X"
-	LIBS += -framework OpenGL -framework Cocoa -framework IOKit -framework CoreVideo `sdl2-config --libs`
+	LIBS += -framework OpenGL -framework Cocoa -framework IOKit -framework CoreVideo `sdl2-config --libs` -lGLEW
 	LIBS += -L/usr/local/lib -L/opt/local/lib
 
 	CXXFLAGS += `sdl2-config --cflags`

Makefile.emscripten

@@ -32,7 +32,7 @@ EMS =
 ##---------------------------------------------------------------------
 
 # ("EMS" options gets added to both CPPFLAGS and LDFLAGS, whereas some options are for linker only)
-EMS += -s USE_SDL=2 -flto -O2
+EMS += -s USE_SDL=2 -flto -O2 -s USE_WEBGL2=1
 EMS += -s DISABLE_EXCEPTION_CATCHING=1
 LDFLAGS += -s WASM=1 -s ALLOW_MEMORY_GROWTH=1 -s NO_EXIT_RUNTIME=0 -s ASSERTIONS=1 -sEXPORTED_FUNCTIONS=[_main,_malloc,_free] -sEXPORTED_RUNTIME_METHODS=[ccall]
 

lib/FrameBuffer.cpp

@@ -0,0 +1,58 @@
+// FrameBuffer.cpp
+
+#include "FrameBuffer.h"
+
+FrameBuffer::FrameBuffer(float width, float height) {
+  glGenFramebuffers(1, &fbo);
+  glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+
+  glGenTextures(1, &texture);
+  glBindTexture(GL_TEXTURE_2D, texture);
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB,
+               GL_UNSIGNED_BYTE, NULL);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
+                         texture, 0);
+
+  glGenRenderbuffers(1, &rbo);
+  glBindRenderbuffer(GL_RENDERBUFFER, rbo);
+  glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height);
+  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
+                            GL_RENDERBUFFER, rbo);
+
+  if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
+    std::cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!"
+              << std::endl;
+
+  glBindFramebuffer(GL_FRAMEBUFFER, 0);
+  glBindTexture(GL_TEXTURE_2D, 0);
+  glBindRenderbuffer(GL_RENDERBUFFER, 0);
+}
+
+FrameBuffer::~FrameBuffer() {
+  glDeleteFramebuffers(1, &fbo);
+  glDeleteTextures(1, &texture);
+  glDeleteRenderbuffers(1, &rbo);
+}
+
+unsigned int FrameBuffer::getFrameTexture() { return texture; }
+
+void FrameBuffer::RescaleFrameBuffer(float width, float height) {
+  glBindTexture(GL_TEXTURE_2D, texture);
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB,
+               GL_UNSIGNED_BYTE, NULL);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
+                         texture, 0);
+
+  glBindRenderbuffer(GL_RENDERBUFFER, rbo);
+  glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height);
+  glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
+                            GL_RENDERBUFFER, rbo);
+}
+
+void FrameBuffer::Bind() const { glBindFramebuffer(GL_FRAMEBUFFER, fbo); }
+
+void FrameBuffer::Unbind() const { glBindFramebuffer(GL_FRAMEBUFFER, 0); }

lib/FrameBuffer.h

@@ -0,0 +1,38 @@
+// FrameBuffer.h
+#ifdef __EMSCRIPTEN__
+#else
+#include "GL/glew.h"
+#endif
+
+#pragma once
+#include <iostream>
+#if defined(__APPLE__)
+#include <SDL2/SDL.h>
+#if defined(IMGUI_IMPL_OPENGL_ES2)
+#include <SDL2/SDL_opengles.h>
+#else
+#include <SDL2/SDL_opengl.h>
+#endif
+#else
+#include <SDL.h>
+#if defined(IMGUI_IMPL_OPENGL_ES2)
+#include <SDL_opengles2.h>
+#else
+#include <SDL_opengl.h>
+#endif
+#endif
+
+class FrameBuffer {
+public:
+  FrameBuffer(float width, float height);
+  ~FrameBuffer();
+  unsigned int getFrameTexture();
+  void RescaleFrameBuffer(float width, float height);
+  void Bind() const;
+  void Unbind() const;
+
+private:
+  unsigned int fbo;
+  unsigned int texture;
+  unsigned int rbo;
+};

lib/nodes/load_image.h

@@ -1,6 +1,6 @@
-
+#include <cstdint>
-#include "../ImNodeFlow.h"
 #include <cstdlib>
+#include <iostream>
 #include <iterator>
 #include <ostream>
 
@@ -20,12 +20,11 @@
 #endif
 #endif
 
+#include "../ImNodeFlow.h"
 #include "../image_model.h"
 #include "../imfilebrowser.h"
 #include "../stb_image.h"
 #include "../uuid.h"
-#include <cstdint>
-#include <iostream>
 
 #ifdef __EMSCRIPTEN__
 #include "../emscripten_browser_file.h"
@@ -54,7 +53,11 @@ public:
     });
   }
 
-  ~Exposure() { stbi_image_free(returnBundle.image); }
+  ~Exposure() {
+    if (returnBundle.loaded) {
+      stbi_image_free(returnBundle.image);
+    }
+  }
 
   void draw() override {
     ImGui::SetNextItemWidth(100);
@@ -158,7 +161,11 @@ public:
     });
   }
 
-  ~Contrast() { stbi_image_free(returnBundle.image); }
+  ~Contrast() {
+    if (returnBundle.loaded) {
+      stbi_image_free(returnBundle.image);
+    }
+  }
 
   void draw() override {
     ImGui::SetNextItemWidth(100);
@@ -263,7 +270,11 @@ public:
     });
   }
 
-  ~SimpleBrightness() { stbi_image_free(returnBundle.image); }
+  ~SimpleBrightness() {
+    if (returnBundle.loaded) {
+      stbi_image_free(returnBundle.image);
+    }
+  }
 
   void draw() override {
     ImGui::SetNextItemWidth(100);

main.cpp

@@ -8,6 +8,13 @@
 // - Documentation        https://dearimgui.com/docs (same as your local docs/
 // folder).
 // - Introduction, links and more at the top of imgui.cpp
+//
+
+#include <cstdint>
+#ifdef __EMSCRIPTEN__
+#else
+#include "GL/glew.h"
+#endif
 
 #include <cstddef>
 #define IMGUI_DEFINE_MATH_OPERATORS
@@ -43,10 +50,136 @@
 #include "lib/emscripten/emscripten_mainloop_stub.h"
 #endif
 
+#include "lib/FrameBuffer.h"
 #include "lib/ImNodeFlow.h"
 
 static bool init = true;
 
+GLuint initShader(const char *vShader, const char *fShader,
+                  const char *outputAttributeName) {
+  struct Shader {
+    GLenum type;
+    const char *source;
+  } shaders[2] = {{GL_VERTEX_SHADER, vShader}, {GL_FRAGMENT_SHADER, fShader}};
+
+  GLuint program = glCreateProgram();
+
+  for (int i = 0; i < 2; ++i) {
+    Shader &s = shaders[i];
+    GLuint shader = glCreateShader(s.type);
+    glShaderSource(shader, 1, (const GLchar **)&s.source, NULL);
+    glCompileShader(shader);
+
+    GLint compiled;
+    glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+    if (!compiled) {
+      std::cerr << " failed to compile:" << std::endl;
+      GLint logSize;
+      glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logSize);
+      char *logMsg = new char[logSize];
+      glGetShaderInfoLog(shader, logSize, NULL, logMsg);
+      std::cerr << logMsg << std::endl;
+      delete[] logMsg;
+
+      exit(EXIT_FAILURE);
+    }
+
+    glAttachShader(program, shader);
+  }
+
+  /* Link output */
+#ifndef EMSCRIPTEN
+  glBindFragDataLocation(program, 0, outputAttributeName);
+#endif
+  /* link  and error check */
+  glLinkProgram(program);
+
+  GLint linked;
+  glGetProgramiv(program, GL_LINK_STATUS, &linked);
+  if (!linked) {
+    std::cerr << "Shader program failed to link" << std::endl;
+    GLint logSize;
+    glGetProgramiv(program, GL_INFO_LOG_LENGTH, &logSize);
+    char *logMsg = new char[logSize];
+    glGetProgramInfoLog(program, logSize, NULL, logMsg);
+    std::cerr << logMsg << std::endl;
+    delete[] logMsg;
+
+    exit(EXIT_FAILURE);
+  }
+
+  /* use program object */
+  glUseProgram(program);
+
+  return program;
+}
+
+uint8_t loadShader() {
+#ifdef EMSCRIPTEN
+  const char *vert = R"(#version 100
+    uniform vec2 offset;
+    attribute vec4 position;
+    attribute vec2 uv;
+    varying vec2 vUV;
+    void main (void)
+    {
+        vUV = uv;
+        gl_Position = position + vec4(offset,0.0,0.0);
+    })";
+#else
+  const char *vert = R"(#version 150
+    uniform vec2 offset;
+    in vec4 position;
+    in vec2 uv;
+    
+    out vec2 vUV;
+    
+    void main (void)
+    {
+        vUV = uv;
+        gl_Position = position + vec4(offset,0.0,0.0);
+    })";
+#endif
+#ifdef EMSCRIPTEN
+  const char *frag = R"(#version 100
+    precision mediump float;
+    
+    varying vec2 vUV;
+    uniform sampler2D tex;
+    
+    void main(void)
+    {
+        gl_FragColor = texture2D(tex,vUV);
+    })";
+#else
+  const char *frag = R"(#version 150
+    in vec2 vUV;
+    out vec4 fragColor;
+    uniform sampler2D tex;
+    void main(void)
+    {
+        fragColor = texture(tex,vUV);
+    })";
+#endif
+  std::cout << "Starting to init" << std::endl;
+  uint8_t shaderProgram = initShader(vert, frag, "fragColor");
+  std::cout << "done to init" << std::endl;
+
+  uint8_t uvAttribute = glGetAttribLocation(shaderProgram, "uv");
+  if (uvAttribute < 0) {
+    std::cerr << "Shader did not contain the 'color' attribute." << std::endl;
+  }
+  uint8_t positionAttribute = glGetAttribLocation(shaderProgram, "position");
+  if (positionAttribute < 0) {
+    std::cerr << "Shader did not contain the 'position' attribute."
+              << std::endl;
+  }
+
+  return shaderProgram;
+}
+
+uint8_t setup() { return loadShader(); }
+
 // Main code
 int main(int, char **) {
   // Setup SDL
@@ -139,7 +272,9 @@ int main(int, char **) {
   ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
   ImFlow::ImNodeFlow editor = ImFlow::ImNodeFlow("Nodes");
 
+  uint8_t shader = 0;
   // Main loop
+
   bool done = false;
 #ifdef __EMSCRIPTEN__
   // For an Emscripten build we are disabling file-system access, so let's not
@@ -201,6 +336,8 @@ int main(int, char **) {
         ImGui::DockBuilderSetNodeSize(dockspace_id, viewport->Size);
         ImGui::DockBuilderDockWindow("Editor", dockspace_id);
         ImGui::DockBuilderFinish(dockspace_id);
+
+        // setup_shaders();
       }
       if (ImGui::BeginMainMenuBar()) {
         if (ImGui::BeginMenu("Add")) {
@@ -230,6 +367,12 @@ int main(int, char **) {
       ImGui::End();
       ImGui::End();
       ImGui::PopStyleVar();
+
+      if (shader != 0) {
+        ImGui::Begin("Shader test");
+        ImGui::Text("Shader ID: %d", shader);
+        ImGui::End();
+      }
     }
 
     // Rendering