From c25427cf4a72a16417349ef4aa3ffd6f2dda0c5b Mon Sep 17 00:00:00 2001
From: Bruno Herbelin <bruno.herbelin@gmail.com>
Date: Mon, 18 Apr 2022 14:02:51 +0200
Subject: [PATCH] Add possibility to define ShadingProgram with GLSL code

---
 ImageProcessingShader.h |  5 +----
 Shader.cpp              | 36 ++++++++++++++++++++++++++----------
 Shader.h                |  8 +++++---
 3 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/ImageProcessingShader.h b/ImageProcessingShader.h
index ee43981..30979ef 100644
--- a/ImageProcessingShader.h
+++ b/ImageProcessingShader.h
@@ -1,10 +1,7 @@
 #ifndef IMAGEPROCESSINGSHADER_H
 #define IMAGEPROCESSINGSHADER_H
 
-#include <glm/glm.hpp>
-
-#include "ImageShader.h"
-
+#include "Shader.h"
 
 class ImageProcessingShader : public Shader
 {
diff --git a/Shader.cpp b/Shader.cpp
index feefeda..bc2b778 100644
--- a/Shader.cpp
+++ b/Shader.cpp
@@ -72,17 +72,30 @@ GLenum blending_destination_function[9] = {GL_ONE_MINUS_SRC_ALPHA,// normal
                                            GL_ONE,   // lighten only
                                            GL_ZERO};
 
-ShadingProgram::ShadingProgram(const std::string& vertex_file, const std::string& fragment_file) :
-    vertex_id_(0), fragment_id_(0), id_(0), vertex_file_(vertex_file), fragment_file_(fragment_file)
+ShadingProgram::ShadingProgram(const std::string& vertex, const std::string& fragment) :
+    vertex_id_(0), fragment_id_(0), id_(0)
 {
+    if (Resource::hasPath(vertex))
+        vertex_file_ = vertex;
+    else
+        vertex_code_ = vertex;
+
+    if (Resource::hasPath(fragment))
+        fragment_file_ = fragment;
+    else
+        fragment_code_ = fragment;
 }
 
 void ShadingProgram::init()
 {
-    vertex_code_ = Resource::getText(vertex_file_);
-    fragment_code_ = Resource::getText(fragment_file_);
-	compile();
-	link();
+    if (vertex_code_.empty())
+        vertex_code_ = Resource::getText(vertex_file_);
+
+    if (fragment_code_.empty())
+        fragment_code_ = Resource::getText(fragment_file_);
+
+    if ( compile() )
+        link();
 }
 
 bool ShadingProgram::initialized()
@@ -90,7 +103,7 @@ bool ShadingProgram::initialized()
     return (id_ != 0);
 }
 
-void ShadingProgram::compile()
+bool ShadingProgram::compile()
 {
     const char* vcode = vertex_code_.c_str();
     vertex_id_ = glCreateShader(GL_VERTEX_SHADER);
@@ -102,7 +115,7 @@ void ShadingProgram::compile()
     glShaderSource(fragment_id_, 1, &fcode, NULL);
     glCompileShader(fragment_id_);
 
-    checkCompileErr();
+    return checkCompileErr();
 }
 
 void ShadingProgram::link()
@@ -117,7 +130,9 @@ void ShadingProgram::link()
     glUniform1i(glGetUniformLocation(id_, "iChannel1"), 1);
     glUseProgram(0);
     glDeleteShader(vertex_id_);
+    vertex_id_ = 0;
     glDeleteShader(fragment_id_);
+    fragment_id_ = 0;
 }
 
 void ShadingProgram::use()
@@ -125,7 +140,7 @@ void ShadingProgram::use()
     if (currentProgram_ == nullptr || currentProgram_ != this)
     {
         currentProgram_ = this;
-        glUseProgram(id_);
+        glUseProgram(id_);  // NB: if not linked, use 0 as default
     }
 }
 
@@ -190,7 +205,7 @@ void ShadingProgram::setUniform<glm::mat4>(const std::string& name, glm::mat4 va
 // 	glUniformMatrix4fv(glGetUniformLocation(id_, name.c_str()), 1, GL_FALSE, val);
 // }
 
-void ShadingProgram::checkCompileErr()
+bool ShadingProgram::checkCompileErr()
 {
     int success;
     char infoLog[1024];
@@ -204,6 +219,7 @@ void ShadingProgram::checkCompileErr()
         glGetShaderInfoLog(fragment_id_, 1024, NULL, infoLog);
         Log::Warning("Error compiling Fragment ShadingProgram:\n%s", infoLog);
 	}
+    return success;
 }
 
 void ShadingProgram::checkLinkingErr()
diff --git a/Shader.h b/Shader.h
index 8b18b41..cdaacc8 100644
--- a/Shader.h
+++ b/Shader.h
@@ -12,7 +12,9 @@ class FrameBuffer;
 class ShadingProgram
 {
 public:
-    ShadingProgram(const std::string& vertex_file, const std::string& fragment_file);
+    // create GLSL Program from resource file (if exist) or code of vertex and fragment shaders
+    ShadingProgram(const std::string& vertex, const std::string& fragment);
+
     void init();
     bool initialized();
     void use();
@@ -23,9 +25,9 @@ public:
 	static void enduse();
 
 private:
-    void checkCompileErr();
+    bool checkCompileErr();
     void checkLinkingErr();
-    void compile();
+    bool compile();
     void link();
     unsigned int vertex_id_, fragment_id_, id_;
     std::string vertex_code_;