From ff4daae11db0ab811cac66e262d289a4107bba4a Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Wed, 27 Dec 2017 23:48:41 +0100
Subject: Add uniform (shader global variable)

---
 src/RenderBackend/OpenGL/PixelShader.cpp   | 18 ++++++++++++++++++
 src/RenderBackend/OpenGL/ShaderProgram.cpp | 21 +++++++++++++++++++++
 src/RenderBackend/OpenGL/ShaderVec.cpp     |  6 ++++++
 3 files changed, 45 insertions(+)

(limited to 'src/RenderBackend/OpenGL')

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);
-- 
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