Use a vector instead of unordered_map for shader variables

src/engine/renderer/opengl/renderer_opengl.cc

@@ -615,18 +615,19 @@ bool RendererOpenGL::BindAttributeLocation(GLuint id,
 GLint RendererOpenGL::GetUniformLocation(
     GLuint id,
     const std::string& name,
-    std::unordered_map<std::string, GLuint>& uniforms) {
+    std::vector<std::pair<std::string, GLuint>>& uniforms) {
   // Check if we've encountered this uniform before.
-  auto i = uniforms.find(name);
+  auto it = std::find_if(uniforms.begin(), uniforms.end(),
+                         [&](auto& r) { return name == std::get<0>(r); });
   GLint index;
-  if (i != uniforms.end()) {
+  if (it != uniforms.end()) {
     // Yes, we already have the mapping.
-    index = i->second;
+    index = std::get<1>(*it);
   } else {
     // No, ask the driver for the mapping and save it.
     index = glGetUniformLocation(id, name.c_str());
     if (index >= 0)
-      uniforms[name] = index;
+      uniforms.emplace_back(std::make_pair(name, index));
     else
       LOG(0) << "Cannot find uniform " << name.c_str() << " (shader: " << id
              << ")";

src/engine/renderer/opengl/renderer_opengl.h

@@ -4,6 +4,7 @@
 #include <memory>
 #include <string>
 #include <unordered_map>
+#include <utility>
 #include <vector>
 
 #include "engine/renderer/opengl/opengl.h"
@@ -94,7 +95,7 @@ class RendererOpenGL final : public Renderer {
 
   struct ShaderOpenGL {
     GLuint id = 0;
-    std::unordered_map<std::string, GLuint> uniforms;
+    std::vector<std::pair<std::string, GLuint>> uniforms;
     bool enable_depth_test = false;
   };
 
@@ -138,9 +139,10 @@ class RendererOpenGL final : public Renderer {
                          std::vector<GeometryOpenGL::Element>& vertex_layout);
   GLuint CreateShader(const char* source, GLenum type);
   bool BindAttributeLocation(GLuint id, const VertexDescription& vd);
-  GLint GetUniformLocation(GLuint id,
-                           const std::string& name,
-                           std::unordered_map<std::string, GLuint>& uniforms);
+  GLint GetUniformLocation(
+      GLuint id,
+      const std::string& name,
+      std::vector<std::pair<std::string, GLuint>>& uniforms);
 };
 
 }  // namespace eng

src/engine/renderer/vulkan/renderer_vulkan.cc

@@ -1876,19 +1876,27 @@ bool RendererVulkan::CreatePipelineLayout(
 
       size_t offset = 0;
       for (uint32_t j = 0; j < pconstants_vertex[0]->member_count; j++) {
+        DCHECK(std::find_if(shader.variables.begin(), shader.variables.end(),
+                            [&](auto& r) {
+                              return pconstants_vertex[0]->members[j].name ==
+                                     std::get<0>(r);
+                            }) == shader.variables.end())
+            << "Duplicate uniform name";
+
         DLOG(0) << __func__
                 << " name: " << pconstants_vertex[0]->members[j].name
                 << " size: " << pconstants_vertex[0]->members[j].size
                 << " padded_size: "
                 << pconstants_vertex[0]->members[j].padded_size;
 
-        shader.variables[pconstants_vertex[0]->members[j].name] = {
-            pconstants_vertex[0]->members[j].size, offset};
+        shader.variables.emplace_back(
+            std::make_tuple(pconstants_vertex[0]->members[j].name,
+                            pconstants_vertex[0]->members[j].size, offset));
         offset += pconstants_vertex[0]->members[j].padded_size;
       }
     }
 
-    // Use the same layout for all decriptor sets.
+    // Use the same layout for all descriptor sets.
     std::vector<VkDescriptorSetLayout> desc_set_layouts;
     for (size_t i = 0; i < binding_count; ++i)
       desc_set_layouts.push_back(descriptor_set_layout_);
@@ -2032,17 +2040,20 @@ template <typename T>
 bool RendererVulkan::SetUniformInternal(ShaderVulkan& shader,
                                         const std::string& name,
                                         T val) {
-  auto it = shader.variables.find(name);
+  auto it = std::find_if(shader.variables.begin(), shader.variables.end(),
+                         [&](auto& r) { return name == std::get<0>(r); });
   if (it == shader.variables.end()) {
     DLOG(0) << "No variable found with name " << name;
     return false;
   }
-  if (it->second[0] != sizeof(val)) {
+
+  if (std::get<1>(*it) != sizeof(val)) {
     DLOG(0) << "Size mismatch for variable " << name;
     return false;
   }
 
-  auto* dst = reinterpret_cast<T*>(shader.push_constants.get() + it->second[1]);
+  auto* dst =
+      reinterpret_cast<T*>(shader.push_constants.get() + std::get<2>(*it));
   *dst = val;
   return true;
 }

src/engine/renderer/vulkan/renderer_vulkan.h

@@ -106,7 +106,7 @@ class RendererVulkan final : public Renderer {
   };
 
   struct ShaderVulkan {
-    std::unordered_map<std::string, std::array<size_t, 2>> variables;
+    std::vector<std::tuple<std::string, size_t, size_t>> variables;
     std::unique_ptr<char[]> push_constants;
     size_t push_constants_size = 0;
     std::vector<std::string> sampler_uniform_names;