Add ability to draw normals

shaders/normal_frag.glsl

@@ -0,0 +1,7 @@
+#version 330 core
+
+out vec4 color;
+
+void main() {
+  color = vec4(1.0, 1.0, 0.0, 1.0);
+}

shaders/normal_geo.glsl

@@ -0,0 +1,34 @@
+#version 330 core
+
+#define MAGNITUDE 0.1
+
+layout (triangles) in;
+layout (line_strip, max_vertices = 6) out;
+
+uniform float time;
+
+in VS_OUT {
+  vec3 vert_normal;
+} gs_in[];
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+void generate_line(int index) {
+  gl_Position = projection * gl_in[index].gl_Position;
+  EmitVertex();
+
+  gl_Position = projection * (gl_in[index].gl_Position + vec4(gs_in[index].vert_normal, 1.0) * MAGNITUDE);
+  EmitVertex();
+
+  EndPrimitive();
+}
+
+void main() {
+  for (int i = 0; i < 3; ++i) {
+    generate_line(i);
+  }
+}

shaders/normal_vert.glsl

@@ -0,0 +1,25 @@
+#version 330 core
+
+layout(location=0) in vec3 position;
+layout(location=1) in vec3 normal;
+layout(location=2) in vec2 uv;
+
+uniform mat3 normal_mat;
+uniform mat4 model;
+
+layout (std140) uniform Common {
+  mat4 projection;
+  mat4 view;
+  vec3 camera_position;
+};
+
+// interface block
+out VS_OUT {
+  vec3 vert_normal;
+} vs_out;
+
+void main() {
+  vs_out.vert_normal = normal_mat * normal;
+
+  gl_Position = view * model * vec4(position, 1.0);
+};

src/main.cc

@@ -48,6 +48,10 @@
 #define max(a, b) (a > b ? a : b)
 #define clamp(v, a, b) (min(max(v, a), b))
 
+#define WIREFRAME 0
+#define NORMALS 0
+#define POINT_LIGHTS 0
+
 enum exit_codes : int {
   EXIT_CODE_SUCCESS,
   EXIT_CODE_SDL_INIT_FAILED,
@@ -59,7 +63,7 @@ enum exit_codes : int {
 
 class Shader {
   public:
-    Shader(const std::string &vert_file, const std::string &frag_file);
+    Shader(const std::string &vert_file, const std::string &frag_file, const std::string &geo_file = "");
     ~Shader();
     void activate();
     void set_int(const char *name, int value);
@@ -71,7 +75,7 @@ class Shader {
     void set_uniform_block_binding_point(const char *block_name, GLuint binding_point);
     GLuint program;
   private:
-    void link_program(GLuint vert, GLuint frag);
+    void link_program(GLuint vert, GLuint frag, GLuint geo);
     GLuint load_and_compile_shader(const std::string &filepath, GLenum shader_type);
     std::string load_shader_from_file(const std::string &filepath);
     static const char *get_shader_type_string(GLenum shader_type);
@@ -269,6 +273,7 @@ int main() {
   Mesh screen = {screen_vertices, screen_indices, {}};
 
   Shader main_shader       {"shaders/vert.glsl",        "shaders/frag.glsl"};
+  Shader normal_vis_shader {"shaders/normal_vert.glsl", "shaders/normal_frag.glsl", "shaders/normal_geo.glsl"};
   Shader light_shader      {"shaders/vert.glsl",        "shaders/light_frag.glsl"};
   Shader skybox_shader     {"shaders/sb_vert.glsl",     "shaders/sb_frag.glsl"};
   Shader reflective_shader {"shaders/vert.glsl",        "shaders/reflective_frag.glsl"};
@@ -372,6 +377,7 @@ int main() {
 
   // Set the shaders binding points
   main_shader.set_uniform_block_binding_point      ("Common", ubo_binding_point);
+  normal_vis_shader.set_uniform_block_binding_point("Common", ubo_binding_point);
   light_shader.set_uniform_block_binding_point     ("Common", ubo_binding_point);
   skybox_shader.set_uniform_block_binding_point    ("Common", ubo_binding_point);
   reflective_shader.set_uniform_block_binding_point("Common", ubo_binding_point);
@@ -489,6 +495,14 @@ int main() {
     main_shader.set_mat3("normal_mat", normal_mat);
     suzanne.draw(main_shader);
 
+#if NORMALS
+    normal_mat = glm::transpose(glm::inverse(view * model));
+    normal_vis_shader.activate();
+    normal_vis_shader.set_mat4("model", model);
+    normal_vis_shader.set_mat3("normal_mat", normal_mat);
+    suzanne.draw(normal_vis_shader);
+#endif
+
     model      = glm::translate(glm::mat4(1.0f), glm::vec3(3.0f, 0.0f, 0.0f));
     normal_mat = glm::transpose(glm::inverse(model));
     reflective_shader.set_mat4("model", model);
@@ -503,15 +517,17 @@ int main() {
     suzanne.draw(refractive_shader);
     glEnable(GL_CULL_FACE);
 
+#if POINT_LIGHTS
     // Draw point lights
-    // for (int i = 0; i < point_light_positions.size(); ++i) {
+    for (int i = 0; i < point_light_positions.size(); ++i) {
-    //   model = glm::translate(glm::mat4(1.0f), point_light_positions[i]);
+      model = glm::translate(glm::mat4(1.0f), point_light_positions[i]);
-    //   model = glm::scale(model, glm::vec3(0.2f));
+      model = glm::scale(model, glm::vec3(0.2f));
-    //   light_shader.activate();
+      light_shader.activate();
-    //   light_shader.set_mat4("model", model);
+      light_shader.set_mat4("model", model);
-    //   light_shader.set_vec3("light_diffuse", light_diffuse);
+      light_shader.set_vec3("light_diffuse", light_diffuse);
-    //   light.draw(light_shader);
+      light.draw(light_shader);
-    // }
+    }
+#endif
 
     // Draw skybox
     glDisable(GL_CULL_FACE);
@@ -521,8 +537,10 @@ int main() {
     skybox_shader.set_int("cubemap", 0);
     skybox.draw(skybox_shader);
 
+#if WIREFRAME
     // wireframe mode
-    // glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+    glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+#endif
 
     // Post processing pass
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
@@ -549,12 +567,19 @@ int main() {
 }
 
 
-Shader::Shader(const std::string &vert_file, const std::string &frag_file) {
+Shader::Shader(const std::string &vert_file, const std::string &frag_file, const std::string &geo_file) {
   GLuint vert = load_and_compile_shader(vert_file, GL_VERTEX_SHADER);
   GLuint frag = load_and_compile_shader(frag_file, GL_FRAGMENT_SHADER);
-  link_program(vert, frag);
+  GLuint geo  = 0;
+  if (geo_file.size() > 0) {
+    geo = load_and_compile_shader(geo_file, GL_GEOMETRY_SHADER);
+  }
+  link_program(vert, frag, geo);
   glDeleteShader(vert);
   glDeleteShader(frag);
+  if (geo > 0) {
+    glDeleteShader(geo);
+  }
 }
 
 Shader::~Shader() {
@@ -604,10 +629,13 @@ void Shader::set_uniform_block_binding_point(const char *block_name, GLuint bind
   glUniformBlockBinding(program, block_index, binding_point);
 }
 
-void Shader::link_program(GLuint vert, GLuint frag) {
+void Shader::link_program(GLuint vert, GLuint frag, GLuint geo) {
   program = glCreateProgram();
   glAttachShader(program, vert);
   glAttachShader(program, frag);
+  if (geo > 0) {
+    glAttachShader(program, geo);
+  }
 
   glLinkProgram(program);
   GLint program_linked;