perf(shadow): increase depth map resolution and refine PCF sampling

assets/shaders/block_f_shader.glsl

@@ -37,16 +37,20 @@ float ShadowCalculation(vec4 fragPosLightSpace, vec3 norm, vec3 lightDir)
     }
     float currentDepth = projCoords.z;
     vec2 texelSize = 1.0 / vec2(textureSize(shadowMap, 0));
-    float bias = 0.0002;
-    bias += max(0.005 * texelSize.x * (1.0 - dot(norm, lightDir)), 0.0);
-
-    float angle = random(gl_FragCoord.xyy) * 6.2831853; // 2*PI
+    float shadow = 0.0;
+    float bias =
+    max(
+        0.0003,
+        0.001 * (1.0 - dot(norm, lightDir))
+    );
+    vec3 seed = vert_pos * 37.0 + sin(vert_pos * 91.7) * 13.0;
+    float angle = random(seed) * 6.2831853;; // 2*PI
     float s = sin(angle), c = cos(angle);
     mat2 rot = mat2(c, -s, s, c);
 
-    float radius = 1.5;
+    float radius = 0.7;
 
-    float shadow = 0.0;
+    
     const int samples = 8;
     for (int i = 0; i < samples; ++i) {
         vec2 offset = rot * poissonDisk[i] * radius * texelSize;
@@ -54,7 +58,25 @@ float ShadowCalculation(vec4 fragPosLightSpace, vec3 norm, vec3 lightDir)
         shadow += (currentDepth - bias > pcfDepth ? 1.0 : 0.0);
     }
     shadow /= float(samples);
+    
+    /*
+    for (int x = -1; x <= 1; ++x) {
+        for (int y = -1; y <= 1; ++y) {
+            vec2 offset = vec2(x, y) * texelSize;
+            float pcfDepth = texture(shadowMap, projCoords.xy + offset).r;
+            shadow += (currentDepth - bias > pcfDepth ? 1.0 : 0.0);
+        }
+    }
+    shadow /= 9.0;
+    */
+    // pcf off
+    //float pcfDepth =
+    //texture(shadowMap, projCoords.xy).r;
 
+    //shadow =
+    //   currentDepth - bias > pcfDepth
+    //    ? 1.0
+    //    : 0.0;
     return shadow;
 }
 

include/Cubed/renderer.hpp

@@ -39,8 +39,7 @@ private:
     static constexpr float NEAR_PLANE = 0.1f;
     static constexpr float SUN_SIZE = 50.0f;
     static constexpr float MOON_SIZE = 50.0f;
-    static constexpr float DEPTH_MAP_WIDTH = 2048.0f;
-    static constexpr float DEPTH_MAP_HEIGHT = 2048.0f;
+    static constexpr float DEPTH_MAP_SIZE = 4096.0f;
     float m_ambient_strength = 0.1f;
 
     const Camera& m_camera;

src/renderer.cpp

@@ -470,8 +470,8 @@ void Renderer::updata_framebuffer(int width, int height) {
     glGenTextures(1, &m_depth_map_texture);
 
     glBindTexture(GL_TEXTURE_2D, m_depth_map_texture);
-    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, DEPTH_MAP_WIDTH,
-                 DEPTH_MAP_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32F, DEPTH_MAP_SIZE,
+                 DEPTH_MAP_SIZE, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
@@ -506,7 +506,7 @@ void Renderer::render_world() {
 
     glm::vec3 cam_pos = m_camera.get_camera_pos();
     glm::vec3 cam_fwd = m_camera.get_camera_front();
-    float half_extent = 256.0f;
+    float half_extent = 128.0f;
 
     glm::vec3 center = cam_pos + cam_fwd * (half_extent * 0.5f);
 
@@ -515,24 +515,27 @@ void Renderer::render_world() {
         fabs(sundir.y) > 0.99f ? glm::vec3(0, 0, 1) : glm::vec3(0, 1, 0);
 
     glm::mat4 light_basis = glm::lookAt(glm::vec3(0.0f), sundir, up);
-    float texels_per_unit = DEPTH_MAP_WIDTH / (half_extent * 2.0f);
+    float texels_per_unit = DEPTH_MAP_SIZE / (half_extent * 2.0f);
     glm::vec3 ls_center = glm::vec3(light_basis * glm::vec4(center, 1.0f));
     ls_center.x = std::round(ls_center.x * texels_per_unit) / texels_per_unit;
     ls_center.y = std::round(ls_center.y * texels_per_unit) / texels_per_unit;
     glm::vec3 snapped_center =
         glm::vec3(glm::inverse(light_basis) * glm::vec4(ls_center, 1.0f));
 
-    float distance = 128.0f;
+    float distance = half_extent * 1.5f;
+    float near_plane = 1.0f;
+    float far_plane = distance + half_extent * 2.0f;
     glm::vec3 light_pos = snapped_center - sundir * distance;
     glm::mat4 light_view = glm::lookAt(light_pos, snapped_center, up);
-    glm::mat4 light_projection = glm::ortho(
-        -half_extent, half_extent, -half_extent, half_extent, 1.0f, 500.0f);
+    glm::mat4 light_projection =
+        glm::ortho(-half_extent, half_extent, -half_extent, half_extent,
+                   near_plane, far_plane);
 
     glm::mat4 light_space_matrix = light_projection * light_view;
     glUniformMatrix4fv(depth_shader.loc("lightSpaceMatrix"), 1, GL_FALSE,
                        glm::value_ptr(light_space_matrix));
 
-    glViewport(0, 0, DEPTH_MAP_WIDTH, DEPTH_MAP_WIDTH);
+    glViewport(0, 0, DEPTH_MAP_SIZE, DEPTH_MAP_SIZE);
     glCullFace(GL_FRONT);
 
     glBindFramebuffer(GL_FRAMEBUFFER, m_depth_map_fbo);