From ca92d8c90f7103db6d7cae4cef49b278d804b474 Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Wed, 20 Dec 2017 20:55:05 +0100
Subject: Create shader using c++ code

---
 src/RenderBackend/OpenGL/VertexShader.cpp | 110 ++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 src/RenderBackend/OpenGL/VertexShader.cpp

(limited to 'src/RenderBackend/OpenGL/VertexShader.cpp')

diff --git a/src/RenderBackend/OpenGL/VertexShader.cpp b/src/RenderBackend/OpenGL/VertexShader.cpp
new file mode 100644
index 0000000..b869624
--- /dev/null
+++ b/src/RenderBackend/OpenGL/VertexShader.cpp
@@ -0,0 +1,110 @@
+#include "../../../include/RenderBackend/OpenGL/VertexShader.hpp"
+#include "../../../include/RenderBackend/OpenGL/CommonShader.hpp"
+#include "../../../include/RenderBackend/OpenGL/opengl.hpp"
+#include <cassert>
+
+using namespace std;
+
+namespace amalgine
+{
+    VertexShaderTooManyAttributes::VertexShaderTooManyAttributes(i32 maxVertexAttributes) : 
+        runtime_error(string("Attempting to define more than ") + to_string(maxVertexAttributes) + " vertex attributes")
+    {
+        
+    }
+    
+    VertexShaderAttributeAlreadyDefined::VertexShaderAttributeAlreadyDefined(const std::string &attributeName) : 
+        runtime_error(string("A vertex attribute with the name ") + attributeName + " has already been defined")
+    {
+        
+    }
+    
+    VertexShaderInvalidAttributeName::VertexShaderInvalidAttributeName(const std::string &attributeName) : 
+        runtime_error(string("Vertex attribute name ") + attributeName + " is invalid")
+    {
+        
+    }
+    
+    VertexShaderFunctionAlreadyDefined::VertexShaderFunctionAlreadyDefined(const std::string &funcName) : 
+        runtime_error(string("Vertex shader function already defined: ") + funcName)
+    {
+        
+    }
+    
+    VertexShader::VertexShader() : locationCounter(0), mainFuncDefined(false)
+    {
+        glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &maxVertexAttribs);
+        writeHeader("#version 330 core\n\n");
+    }
+    
+    const string& VertexShader::getInputAttributeName(i32 attributeIndex)
+    {
+        assert(attributeIndex < vertexAttributeNames.size());
+        return vertexAttributeNames[attributeIndex];
+    }
+    
+    ShaderInputVec2 VertexShader::defineInputVec2(const std::string &name)
+    {
+        i32 attributeIndex = defineInputVariable(name, "vec2");
+        return ShaderInputVec2(this, attributeIndex);
+    }
+    
+    void VertexShader::defineMain(VertexShaderMainFunc mainFunc)
+    {
+        if(mainFuncDefined)
+            throw VertexShaderFunctionAlreadyDefined("main");
+        
+        writeBody("void main() {\n");
+        ShaderVec4 glPosition = mainFunc();
+        mainFuncDefined = true;
+        writeBody("gl_Position = ");
+        writeBody(glPosition.getOutput());
+        writeBody(";\n}\n\n");
+    }
+    
+    i32 VertexShader::defineInputVariable(const string &variableName, const char *typeName)
+    {
+        if(!isShaderVariableNameValid(variableName.c_str()))
+            throw VertexShaderInvalidAttributeName(variableName);
+        
+        if(locationCounter + 1 > maxVertexAttribs)
+            throw VertexShaderTooManyAttributes(maxVertexAttribs);
+        
+        if(vertexAttributes.find(variableName) != vertexAttributes.end())
+            throw VertexShaderAttributeAlreadyDefined(variableName);
+        
+        i32 attributeIndex = locationCounter;
+        vertexAttributes[variableName] = locationCounter;
+        vertexAttributeNames.push_back(variableName);
+        
+        writeHeader("layout(location = ");
+        writeHeader(to_string(locationCounter));
+        ++locationCounter;
+        writeHeader(") in ");
+        writeHeader(typeName);
+        writeHeader(" ");
+        writeHeader(variableName);
+        writeHeader(";\n");
+        return attributeIndex;
+    }
+    
+    string VertexShader::build()
+    {
+        std::string result;
+        result.reserve(header.size() + 2 + body.size());
+        result += header;
+        result += "\n";
+        result += body;
+        return result;
+    }
+    
+    void VertexShader::writeHeader(const string &code)
+    {
+        header += code;
+    }
+    
+    void VertexShader::writeBody(const string &code)
+    {
+        body += code;
+    }
+}
-- 
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