Implement basic shadows

Still shadow acne, but working in principle

ECS/Components/MouseLook.h

@@ -15,7 +15,7 @@ struct MouseLook {
 
     glm::quat rotation;
 
-    bool is_active;
+    bool is_active = true;
 };
 
 #endif //ECSGAME_MOUSELOOK_H

ECS/Components/Movement.h

@@ -14,7 +14,7 @@ struct Movement {
 
     glm::vec3 velocity;
 
-    bool is_active;
+    bool is_active = true;
 };
 
 #endif //ECSGAME_MOVEMENT_H

ECS/Components/PathMove.h

@@ -35,7 +35,7 @@ struct PathMove {
 
     PathMove(double speed, Path path, Views views) : speed(speed), path(path), views(views) {}
 
-    bool is_active;
+    bool is_active = false;
     double speed;
     float time_passed = 0.0;
     int current_point_index = 0;

ECS/Systems/RenderSystem.h

@@ -18,6 +18,38 @@
 
 using namespace ECS;
 
+// For debugging:
+// renderQuad() renders a 1x1 XY quad in NDC
+// -----------------------------------------
+unsigned int quadVAO = 0;
+unsigned int quadVBO;
+void renderQuad()
+{
+    if (quadVAO == 0)
+    {
+        float quadVertices[] = {
+            // positions        // texture Coords
+            -1.0f,  1.0f, 0.0f, 0.0f, 1.0f,
+            -1.0f, -1.0f, 0.0f, 0.0f, 0.0f,
+             1.0f,  1.0f, 0.0f, 1.0f, 1.0f,
+             1.0f, -1.0f, 0.0f, 1.0f, 0.0f,
+        };
+        // setup plane VAO
+        glGenVertexArrays(1, &quadVAO);
+        glGenBuffers(1, &quadVBO);
+        glBindVertexArray(quadVAO);
+        glBindBuffer(GL_ARRAY_BUFFER, quadVBO);
+        glBufferData(GL_ARRAY_BUFFER, sizeof(quadVertices), &quadVertices, GL_STATIC_DRAW);
+        glEnableVertexAttribArray(0);
+        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
+        glEnableVertexAttribArray(1);
+        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
+    }
+    glBindVertexArray(quadVAO);
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    glBindVertexArray(0);
+}
+
 class RenderSystem : public EntitySystem {
 public:
     struct RenderObject {
@@ -36,9 +68,11 @@ public:
 
             // 0 can't be a valid texture name, so we use it for meshes without textures here
             if (texture_id != 0) {
+                glActiveTexture(GL_TEXTURE1);
                 glBindTexture(GL_TEXTURE_2D, texture_id);
             }
 
+            // TODO: Not always required (not when rendering shadows) - make functions separate?
             shader.setFloat("diffuseStrength", material.diffuse);
             shader.setFloat("specularStrength", material.specular);
 
@@ -125,40 +159,113 @@ public:
         return renderObjects;
     }
 
-    void render(World *pWorld, Shader shader) {
+    RenderSystem() {
+        // Configure depth map
+        glGenFramebuffers(1, &depthMapFBO);
+        // create depth texture
+        glGenTextures(1, &depthMap);
+        glBindTexture(GL_TEXTURE_2D, depthMap);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, shadow_width, shadow_height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+        // attach depth texture as FBO's depth buffer
+        glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
+        glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthMap, 0);
+        glDrawBuffer(GL_NONE);
+        glReadBuffer(GL_NONE);
+        glBindFramebuffer(GL_FRAMEBUFFER, 0);
+    }
+
+
+    void render(World *pWorld, Shader normalShader, Shader shadowShader, Shader debugShader) {
         pWorld->each<Camera, Transform>([&](Entity *ent, ComponentHandle<Camera> camera, ComponentHandle<Transform> cameraTransform) {
+            // Common
             glClearColor(0.6f, 0.9f, 0.9f, 1.0f);
             glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-            shader.use();
+            std::vector<std::vector<RenderObject>> allRenderObjects = getRenderObjects(pWorld, cameraTransform->get_origin());
+            std::vector<RenderObject> renderObjects = allRenderObjects[0];
+            std::vector<RenderObject> transparentRenderObjects = allRenderObjects[1];
+
+            // Calculate matrix for lighting
+            // Get light direction
+            // TODO: Currently only the last light is used!
+            glm::vec3 lightDirection;
+            pWorld->each<DirectionalLight>([&](Entity *ent, ComponentHandle<DirectionalLight> light) {
+                lightDirection = light->direction;
+            });
+            float near_plane = 1.0f, far_plane = 100.0f;
+            glm::mat4 lightProjection = glm::ortho(-20.0f, 20.0f, -20.0f, 20.0f, near_plane, far_plane);
+            glm::mat4 lightView = glm::lookAt(lightDirection * 40.0f, -lightDirection, glm::vec3(0.0, 1.0, 0.0));
+            glm::mat4 lightSpaceMatrix = lightProjection * lightView;
+
+            // Render shadows
+            shadowShader.use();
+
+            shadowShader.setMat4("lightSpaceMatrix", lightSpaceMatrix);
+            
+            glViewport(0, 0, shadow_width, shadow_height);
+            glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
+            for (const RenderObject &obj : renderObjects) {
+                obj.render(shadowShader);
+            }
+            for (const RenderObject &obj : transparentRenderObjects) {
+                obj.render(shadowShader);
+            }
+            glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+            // reset viewport
+            glViewport(0, 0, screen_width, screen_height);
+            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+
+            // Render normal
+            normalShader.use();
 
             // Lighting
-            // TODO: Currently only the last light is used!
-            pWorld->each<DirectionalLight>([&](Entity *ent, ComponentHandle<DirectionalLight> light) {
-                shader.setVec3("lightDirection", light->direction);
-            });
+            normalShader.setVec3("lightDirection", lightDirection);
+            normalShader.setMat4("lightSpaceMatrix", lightSpaceMatrix);
 
             glm::vec3 cameraPos = cameraTransform->get_origin();
 
             glm::mat4 view = cameraTransform->matrix;
             view[3] = glm::vec4(cameraPos, 1.0);
 
-            shader.setMat4("projection", camera->projection);
-            shader.setMat4("view", glm::inverse(view));
-            shader.setVec3("cameraPosition", cameraTransform->get_origin());
+            normalShader.setMat4("projection", camera->projection);
+            normalShader.setMat4("view", glm::inverse(view));
+            normalShader.setVec3("cameraPosition", cameraTransform->get_origin());
 
-            std::vector<std::vector<RenderObject>> allRenderObjects = getRenderObjects(pWorld, cameraPos);
-            std::vector<RenderObject> renderObjects = allRenderObjects[0];
-            std::vector<RenderObject> transparentRenderObjects = allRenderObjects[1];
+            // Bind shadow texture
+            glActiveTexture(GL_TEXTURE0);
+            glBindTexture(GL_TEXTURE_2D, depthMap);
 
             for (const RenderObject &obj : renderObjects) {
-                obj.render(shader);
+                obj.render(normalShader);
             }
             for (const RenderObject &obj : transparentRenderObjects) {
-                obj.render(shader);
+                obj.render(normalShader);
             }
+
+            // Render the light's depth map to a quad for debugging
+            debugShader.use();
+            debugShader.setFloat("near_plane", near_plane);
+            debugShader.setFloat("far_plane", far_plane);
+            glActiveTexture(GL_TEXTURE0);
+            glBindTexture(GL_TEXTURE_2D, depthMap);
+            //renderQuad(); // TODO: Add actual code switch instead of commenting
         });
     }
+
+    int screen_width = 1280;
+    int screen_height = 720;
+
+    int shadow_width = 1024;
+    int shadow_height = 1024;
+
+    unsigned int depthMap;
+    unsigned int depthMapFBO;
 };
 
 #endif //ECSGAME_RENDERSYSTEM_H

Shaders/debug-fragment.fs

@@ -0,0 +1,23 @@
+#version 330 core
+out vec4 FragColor;
+
+in vec2 TexCoords;
+
+uniform sampler2D depthMap;
+uniform float near_plane;
+uniform float far_plane;
+
+// required when using a perspective projection matrix
+float LinearizeDepth(float depth)
+{
+    float z = depth * 2.0 - 1.0; // Back to NDC 
+    return (2.0 * near_plane * far_plane) / (far_plane + near_plane - z * (far_plane - near_plane));	
+}
+
+void main()
+{             
+    float depthValue = texture(depthMap, TexCoords).r;
+    // FragColor = vec4(vec3(LinearizeDepth(depthValue) / far_plane), 1.0); // perspective
+    FragColor = vec4(vec3(depthValue), 1.0); // orthographic
+}
+

Shaders/debug-vertex.vs

@@ -0,0 +1,12 @@
+#version 330 core
+layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec2 aTexCoords;
+
+out vec2 TexCoords;
+
+void main()
+{
+    TexCoords = aTexCoords;
+    gl_Position = vec4(aPos, 1.0);
+}
+

Shaders/default-fragment.fs

@@ -4,14 +4,38 @@ out mediump vec4 FragColor;
 in mediump vec2 TexCoord;
 in mediump vec3 Normal;
 in mediump vec3 FragPos;
+in mediump vec4 FragPosLightSpace;
+
+layout(binding=0) uniform sampler2D shadowMap;
+layout(binding=1) uniform sampler2D tex;
 
-uniform sampler2D tex;
 uniform mediump vec3 lightDirection;
 uniform mediump vec3 cameraPosition;
 
 uniform mediump float diffuseStrength;
 uniform mediump float specularStrength;
 
+mediump float ShadowCalculation(vec4 fragPosLightSpace)
+{
+    // perform perspective divide
+    mediump vec3 projCoords = fragPosLightSpace.xyz / fragPosLightSpace.w;
+    // transform to [0,1] range
+    projCoords = projCoords * 0.5 + 0.5;
+
+    // If we're outside of [0.0, 1.0] in the coordinates, return 0
+    if (projCoords.x < 0.0 || projCoords.y < 0.0 || projCoords.x > 1.0 || projCoords.y > 1.0) return 0.0;
+        
+    // get closest depth value from light's perspective (using [0,1] range fragPosLight as coords)
+    mediump float closestDepth = texture(shadowMap, projCoords.xy).r; 
+    // get depth of current fragment from light's perspective
+    mediump float currentDepth = projCoords.z;
+    // check whether current frag pos is in shadow
+    mediump float shadow = currentDepth > closestDepth  ? 1.0 : 0.0;
+
+    return shadow;
+}  
+
+
 void main()
 {
     mediump vec4 texColor = texture(tex, TexCoord);
@@ -33,8 +57,11 @@ void main()
 
     mediump float spec = pow(max(dot(viewDir, reflectDir), 0.0), 32.0);
 
+    // Shadow
+    mediump float shadow = ShadowCalculation(FragPosLightSpace); 
+
     // Total
-    mediump float light = min(diff * diffuseStrength + ambient + spec * specularStrength, 1.0);
+    mediump float light = min(diff * diffuseStrength + ambient + spec * specularStrength - shadow * 0.5 + 0.5, 2.0);
 
     // Assign resulting color
     mediump vec3 color = texColor.xyz * light;

Shaders/default-vertex.vs

@@ -6,10 +6,12 @@ layout (location = 2) in vec2 UV;
 out vec2 TexCoord;
 out vec3 Normal;
 out vec3 FragPos;
+out vec4 FragPosLightSpace;
 
 uniform mat4 model;
 uniform mat4 view;
 uniform mat4 projection;
+uniform mat4 lightSpaceMatrix;
 
 void main()
 {
@@ -17,4 +19,5 @@ void main()
     TexCoord = UV;
     Normal = NORMAL;
     FragPos = vec3(model * vec4(aPos, 1.0));
+    FragPosLightSpace = lightSpaceMatrix * vec4(FragPos, 1.0);
 }

Shaders/shadow-fragment.fs

@@ -0,0 +1,7 @@
+#version 330 core
+
+void main()
+{      
+    // This happens implicitly anyways       
+    // gl_FragDepth = gl_FragCoord.z;
+}

Shaders/shadow-vertex.vs

@@ -0,0 +1,10 @@
+#version 330 core
+layout (location = 0) in vec3 aPos;
+
+uniform mat4 lightSpaceMatrix;
+uniform mat4 model;
+
+void main()
+{
+    gl_Position = lightSpaceMatrix * model * vec4(aPos, 1.0);
+}

main.cpp

@@ -112,6 +112,7 @@ int main() {
             glm::angleAxis(glm::radians(180.f), glm::vec3(0.f, 1.f, 0.f))
         })
     );
+    player->get<Transform>()->set_origin(glm::vec3(0.0, 3.0, 4.0));
 
     Entity *monkey = world->create();
     monkey->assign<Transform>();
@@ -172,6 +173,8 @@ int main() {
     sun->assign<DirectionalLight>(glm::normalize(glm::vec3(1.0, 1.0, 1.0)));
 
     Shader defaultShader("Shaders/default-vertex.vs", "Shaders/default-fragment.fs");
+    Shader shadowShader("Shaders/shadow-vertex.vs", "Shaders/shadow-fragment.fs");
+    Shader debugShader("Shaders/debug-vertex.vs", "Shaders/debug-fragment.fs");
 
     double timeInLastFrame = glfwGetTime();
     double elapsed_time = 0.0;
@@ -184,7 +187,7 @@ int main() {
         elapsed_time += delta;
 
         world->tick(delta);
-        renderSystem->render(world, defaultShader);
+        renderSystem->render(world, defaultShader, shadowShader, debugShader);
 
         /* Swap front and back buffers */
         glfwSwapBuffers(window);