From da66c30a110233f7c8b71b5e6aa8dd804879c1b6 Mon Sep 17 00:00:00 2001
From: LaG1924 <lag1924@gmail.com>
Date: Sun, 5 Dec 2021 05:42:15 +0500
Subject: Added blending

---
 src/Gal.hpp    |  7 +++++++
 src/GalOgl.cpp | 21 ++++++++++++++++++++-
 src/Rml.cpp    |  2 ++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/Gal.hpp b/src/Gal.hpp
index 76db560..fe99dc7 100644
--- a/src/Gal.hpp
+++ b/src/Gal.hpp
@@ -86,6 +86,11 @@ namespace Gal {
         TriangleFan,
     };
 
+    enum class Blending {
+        Opaque,
+        Additive,
+    };
+
     struct VertexAttribute {
         std::string name;
         Type type;
@@ -186,6 +191,8 @@ namespace Gal {
 
         virtual void SetPrimitive(Primitive primitive) = 0;
 
+        virtual void SetBlending(Blending blendingMode) = 0;
+
         virtual std::shared_ptr<BufferBinding> BindVertexBuffer(std::vector<VertexAttribute> &&bufferLayout) = 0;
 
         virtual std::shared_ptr<BufferBinding> BindIndexBuffer() = 0;
diff --git a/src/GalOgl.cpp b/src/GalOgl.cpp
index c7344fe..4ac6c84 100644
--- a/src/GalOgl.cpp
+++ b/src/GalOgl.cpp
@@ -89,6 +89,7 @@ class OglState {
     GLuint activeTextureUnit = 0;
     GLint vpX = 0, vpY = 0;
     GLsizei vpW = 0, vpH = 0;
+    bool blending = false;
 
 public:
 
@@ -162,6 +163,16 @@ public:
         glCheckError();
     }
 
+    void EnableBlending(bool enable) {
+        if (enable != blending) {
+            blending = enable;
+            if (blending)
+                glEnable(GL_BLEND);
+            else
+                glDisable(GL_BLEND);
+        }
+    }
+
 } oglState;
 
 std::unique_ptr<ImplOgl> impl;
@@ -791,6 +802,7 @@ struct PipelineConfigOgl : public PipelineConfig {
     std::shared_ptr<FramebufferOgl> targetFb;
     std::vector<std::vector<VertexAttribute>> vertexBuffers;
     Primitive vertexPrimitive = Primitive::Triangle;
+    Blending blending = Blending::Opaque;
 
     virtual void SetVertexShader(std::shared_ptr<Shader> shader) override {
         vertexShader = std::static_pointer_cast<ShaderOgl,Shader>(shader);
@@ -818,6 +830,10 @@ struct PipelineConfigOgl : public PipelineConfig {
         vertexPrimitive = primitive;
     }
 
+    virtual void SetBlending(Blending blendingMode) override {
+        blending = blendingMode;
+    }
+
     virtual std::shared_ptr<BufferBinding> BindVertexBuffer(std::vector<VertexAttribute> &&bufferLayout) override {
         auto binding = std::make_shared<BufferBindingOgl>(vertexBuffers.size());
         vertexBuffers.push_back(bufferLayout);
@@ -901,12 +917,14 @@ struct PipelineOgl : public Pipeline {
     };
     std::vector<VertexBindingCommand> vertexBindCmds;
     Primitive primitive;
+    Blending blending;
     std::shared_ptr<FramebufferOgl> target;
     
     virtual void Activate() override {
         oglState.UseProgram(program);
         oglState.BindFbo(target->fbo);
         oglState.SetViewport(target->vpX, target->vpY, target->vpW, target->vpH);
+        oglState.EnableBlending(blending == Blending::Additive);
         if (target->fbo)
             glDrawBuffers(target->attachments.size(), target->attachments.data());
 
@@ -1076,7 +1094,7 @@ struct ImplOgl : public Impl {
         glCullFace(GL_BACK);
         glFrontFace(GL_CCW);
 
-        glEnable(GL_BLEND);
+        oglState.EnableBlending(true);
         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
         glCheckError();
         if (glActiveTexture == nullptr) {
@@ -1201,6 +1219,7 @@ struct ImplOgl : public Impl {
         auto config = std::static_pointer_cast<PipelineConfigOgl, PipelineConfig>(pipelineConfig);
 
         pipeline->primitive = config->vertexPrimitive;
+        pipeline->blending = config->blending;
 
         pipeline->target = config->targetFb;
         if (!pipeline->target)
diff --git a/src/Rml.cpp b/src/Rml.cpp
index 746f6a4..f6fff44 100644
--- a/src/Rml.cpp
+++ b/src/Rml.cpp
@@ -68,6 +68,7 @@ RmlRenderInterface::RmlRenderInterface() {
         pipelineConfig->SetTarget(gal->GetDefaultFramebuffer());
         pipelineConfig->SetVertexShader(gal->LoadVertexShader(vertexSource));
         pipelineConfig->SetPixelShader(gal->LoadPixelShader(pixelSource));
+        pipelineConfig->SetBlending(Gal::Blending::Additive);
 
         auto vertBuffBind = pipelineConfig->BindVertexBuffer({
             {"pos", Gal::Type::Vec2},
@@ -92,6 +93,7 @@ RmlRenderInterface::RmlRenderInterface() {
         texPipelineConfig->SetTarget(gal->GetDefaultFramebuffer());
         texPipelineConfig->SetVertexShader(gal->LoadVertexShader(vertexSource));
         texPipelineConfig->SetPixelShader(gal->LoadPixelShader(texPixelSource));
+        texPipelineConfig->SetBlending(Gal::Blending::Additive);
 
         auto texVertBuffBind = texPipelineConfig->BindVertexBuffer({
             {"pos", Gal::Type::Vec2},
-- 
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