Add tangent vertex-attribute

Simplify tangent calculation

Author: knapeczadam

shaders/shader_2d.vert

@@ -4,6 +4,7 @@ layout (location = 0) in vec3 position;
 layout (location = 1) in vec3 color;
 layout (location = 2) in vec3 normal;
 layout (location = 3) in vec2 uv;
+layout (location = 4) in vec3 tangent;
 
 layout (location = 0) out vec3 frag_color;
 

shaders/shader_3d.frag

@@ -23,8 +23,6 @@ layout (set = 0, binding = 0) uniform global_ubo
     int num_lights;
 } ubo;
 
-layout (set = 0, binding = 1) uniform sampler2D image;
-
 layout (push_constant) uniform Push 
 {
     mat4 model_matrix;
@@ -61,6 +59,5 @@ void main()
 
     }
 
-    vec4 image_color = texture(image, frag_uv);
-    out_color = vec4((diffuse_light * frag_color + specular_light * frag_color) * image_color, 1.0f);
+    out_color = vec4(diffuse_light * frag_color + specular_light * frag_color, 1.0f);
 }

shaders/shader_3d.vert

@@ -4,6 +4,7 @@ layout (location = 0) in vec3 position;
 layout (location = 1) in vec3 color;
 layout (location = 2) in vec3 normal;
 layout (location = 3) in vec2 uv;
+layout (location = 4) in vec3 tangent;
 
 layout(location = 0) out vec3 frag_color;
 layout(location = 1) out vec3 frag_pos_world;

src/model.cpp

@@ -88,6 +88,14 @@ namespace dae
             .offset   = offsetof(vertex, uv)
         };
         attribute_descriptions.push_back(uv);
+
+        VkVertexInputAttributeDescription tangent{
+            .location = 4,
+            .binding  = 0,
+            .format   = VK_FORMAT_R32G32B32_SFLOAT,
+            .offset   = offsetof(vertex, tangent)
+        };
+        attribute_descriptions.push_back(tangent);
 
         return attribute_descriptions;
     }
@@ -167,28 +175,31 @@ namespace dae
                 vertex &v0 = vertices[indices[i + 0]];
                 vertex &v1 = vertices[indices[i + 1]];
                 vertex &v2 = vertices[indices[i + 2]];
-
-                glm::vec3 edge0 = v1.position - v0.position;
-                glm::vec3 edge1 = v2.position - v0.position;
-
+            
+                glm::vec3 edge1 = v1.position - v0.position;
+                glm::vec3 edge2 = v2.position - v0.position;
+            
                 glm::vec2 uv0 = v0.uv;
                 glm::vec2 uv1 = v1.uv;
                 glm::vec2 uv2 = v2.uv;
-
-                glm::vec2 diff_x = {uv1.x - uv0.x, uv2.x - uv0.x};
-                glm::vec2 diff_y = {uv1.y - uv0.y, uv2.y - uv0.y};
-                float r = 1.0f / (diff_x.x * diff_y.y - diff_y.x * diff_x.y);
-
-                glm::vec3 tangent = (edge0 * diff_y.y - edge1 * diff_y.x) * r;
-                v0.tangent += tangent;
-                v1.tangent += tangent;
-                v2.tangent += tangent;
-            }
-
-            // Create the tangents (reject)
-            for (auto &vertex : vertices)
-            {
-                vertex.tangent = glm::normalize(reject(vertex.tangent, vertex.normal));
+            
+                glm::vec2 delta_uv1 = uv1 - uv0;
+                glm::vec2 delta_uv2 = uv2 - uv0;
+
+                float f = 1.0f / (delta_uv1.x * delta_uv2.y - delta_uv2.x * delta_uv1.y);
+
+                glm::vec3 tangent = f * (delta_uv2.y * edge1 - delta_uv1.y * edge2);
+                tangent = glm::normalize(tangent);
+
+                float sx = delta_uv1.x;
+                float sy = delta_uv2.x;
+                float tx = delta_uv1.y;
+                float ty = delta_uv2.y;
+                float handedness = (sx * ty - sy * tx) > 0.0f ? 1.0f : -1.0f;
+                tangent *= handedness;
+                v0.tangent = tangent;
+                v1.tangent = tangent;
+                v2.tangent = tangent;
             }
         }
     }

src/systems/point_light_system.cpp

@@ -99,7 +99,6 @@ void point_light_system::render(frame_info &frame_info)
             );
             vkCmdDraw(frame_info.command_buffer, 6, 1, 0, 0);
         }
-        
     }
 
     void point_light_system::create_pipeline_layout(VkDescriptorSetLayout global_set_layout)

src/systems/render_system_3d.cpp

@@ -1,14 +1,13 @@
 #include "render_system_3d.h"
 
 // Standard includes
+#include <ranges>
 #include <stdexcept>
 
 // GLM includes
 #define GLM_FORCE_RADIANS
 #define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <ranges>
 #include <glm/glm.hpp>
-#include <glm/gtc/constants.hpp>
 
 namespace dae
 {