4 files changed, 68 insertions, 5 deletions

diff --git a/src/RenderBackend/OpenGL/PixelShader.cpp b/src/RenderBackend/OpenGL/PixelShader.cpp
index 8aa4d9a..f263513 100644
--- a/src/RenderBackend/OpenGL/PixelShader.cpp
+++ b/src/RenderBackend/OpenGL/PixelShader.cpp
@@ -49,6 +49,24 @@ namespace amalgine
         return ShaderOutputVec4(this, attributeIndex);
     }
     
+    // TODO: Generate warning if global variable is defined but not assigned to?
+    ShaderGlobalVec3 PixelShader::defineGlobalVec3(const std::string &name)
+    {
+        if(!isShaderVariableNameValid(name.c_str()))
+            throw PixelShaderInvalidAttributeName(name);
+        
+        if(globalAttributes.find(name) != globalAttributes.end())
+            throw PixelShaderAttributeAlreadyDefined(name);
+        
+        writeHeader("uniform vec3 ");
+        writeHeader(name);
+        writeHeader(";\n");
+        
+        ShaderGlobalVec3 globalVec(name);
+        globalAttributes[name] = globalVec.getVecObject();
+        return ShaderGlobalVec3(globalVec);
+    }
+    
     i32 PixelShader::defineOutputVariable(const string &variableName, const char *typeName)
     {
         if(!isShaderVariableNameValid(variableName.c_str()))
diff --git a/src/RenderBackend/OpenGL/ShaderProgram.cpp b/src/RenderBackend/OpenGL/ShaderProgram.cpp
index 40f5b6c..aceda3b 100644
--- a/src/RenderBackend/OpenGL/ShaderProgram.cpp
+++ b/src/RenderBackend/OpenGL/ShaderProgram.cpp
@@ -12,6 +12,12 @@ namespace amalgine
         
     }
     
+    ShaderProgramNonExistingGlobalVariable::ShaderProgramNonExistingGlobalVariable(const char *variableName) : 
+        runtime_error(string("There is no shader global variable with the name '") + variableName + "'")
+    {
+        
+    }
+    
     ShaderProgram::ShaderProgram() : built(false)
     {
         shaderProgramId = glCreateProgram();
@@ -84,4 +90,19 @@ namespace amalgine
             throw ShaderProgramUsedBeforeBuilt();
         }
     }
+    
+    ShaderProgramGlobalVec3 ShaderProgram::getGlobalVec3(const char *name)
+    {
+        if(built)
+        {
+            GLint uniformId = glGetUniformLocation(shaderProgramId, name);
+            if(uniformId == -1)
+                throw ShaderProgramNonExistingGlobalVariable(name);
+            return ShaderProgramGlobalVec3(this, uniformId);
+        }
+        else
+        {
+            throw ShaderProgramUsedBeforeBuilt();
+        }
+    }
 }
diff --git a/src/RenderBackend/OpenGL/ShaderVec.cpp b/src/RenderBackend/OpenGL/ShaderVec.cpp
index 3bbe0be..dd3bbe5 100644
--- a/src/RenderBackend/OpenGL/ShaderVec.cpp
+++ b/src/RenderBackend/OpenGL/ShaderVec.cpp
@@ -20,6 +20,12 @@ namespace amalgine
         return AttributeType::NONE;
     }
     
+    void ShaderProgramGlobalVec3::set(f32 x, f32 y, f32 z)
+    {
+        shaderProgram->use();
+        glUniform3f(uniformId, x, y, z);
+    }
+    
     const string& ShaderInputVec2::getName() const
     {
         return vertexShader->getInputAttributeName(attributeIndex);
diff --git a/src/main.cpp b/src/main.cpp
index a04fb99..ada75e2 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -16,6 +16,7 @@
 using namespace amalgine;
 using namespace std;
 
+void glfwErrorHandler(int errorCode, const char *errorDescription);
 void initGlfw();
 void initGlew();
 GLFWwindow *createWindow();
@@ -26,6 +27,7 @@ CompiledPixelShader* createPixelShader();
 int main()
 {
     initGlfw();
+    glfwSetErrorCallback(glfwErrorHandler);
     GLFWwindow *window = createWindow();
     
     DeviceFrame frame;
@@ -35,10 +37,9 @@ int main()
         Vertex2D(0.5f, -0.5f),
         Vertex2D(-0.5f, -0.5f)
     );
-    
+    DataView<Triangle2D> cpuTriangles(&cpuTriangle, 1);
     DeviceMemory *gpuTriangle = frame.alloc();
-    DataView<Triangle2D> triangles(&cpuTriangle, 1);
-    gpuTriangle->copy(triangles, DeviceMemory::StorageType::STATIC);
+    gpuTriangle->copy(cpuTriangles, DeviceMemory::StorageType::STATIC);
     
     CompiledVertexShader *vertexShader = createVertexShader(*gpuTriangle);
     CompiledPixelShader *pixelShader = createPixelShader();
@@ -46,7 +47,13 @@ int main()
     ShaderProgram shaderProgram;
     shaderProgram.setVertexShader(vertexShader);
     shaderProgram.setPixelShader(pixelShader);
+    // Make ShaderProgram.build return an object which we can do things on? since some operations
+    // require the shader to be built to be used
     Result<bool> shaderBuildResult = shaderProgram.build();
+    
+    ShaderProgramGlobalVec3 triangleColor = shaderProgram.getGlobalVec3("triangleColor");
+    triangleColor.set(1.0f, 0.0f, 0.0f);
+    
     if(!shaderBuildResult)
     {
         fprintf(stderr, "Failed to build shader program: %s\n", shaderBuildResult.getErrorMsg().c_str());
@@ -59,6 +66,10 @@ int main()
         if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
             glfwSetWindowShouldClose(window, GL_TRUE);
 
+        // Set color for clearing
+        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+        // Do the actual screen clearing, using the color set using glClearColor
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
         shaderProgram.use();
         frame.draw();
         glfwSwapBuffers(window);
@@ -68,6 +79,11 @@ int main()
     return 0;
 }
 
+void glfwErrorHandler(int errorCode, const char *errorDescription)
+{
+    printf("GLFW error code: %d, description: %s\n", errorCode, errorDescription);
+}
+
 void initGlfw()
 {
     if(!glfwInit())
@@ -107,6 +123,7 @@ GLFWwindow* createWindow()
 
     glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);
     glfwMakeContextCurrent(window);
+    glfwSwapInterval(0);
     initGlew();
     return window;
 }
@@ -135,11 +152,12 @@ CompiledVertexShader* createVertexShader(const DeviceMemory &inputData)
 CompiledPixelShader* createPixelShader()
 {
     PixelShader pixelShader;
+    ShaderGlobalVec3 triangleColor = pixelShader.defineGlobalVec3("triangleColor");
     ShaderOutputVec4 outColor = pixelShader.defineOutputVec4("outColor");
     
-    pixelShader.defineMain([&outColor]()
+    pixelShader.defineMain([&triangleColor, &outColor]()
     {
-        outColor = ShaderVec4(1.0f, 1.0f, 1.0f, 1.0f);
+        outColor = ShaderVec4(triangleColor, 1.0f);
     });
     
     Result<CompiledPixelShader*> compiledPixelShader = pixelShader.compile();