Embedded Files
https://www.khronos.org/opengl/wiki/Vertex_Rendering#Indirect_rendering
Libraries:
GLM (math library)
GLEW (OpenGL functionality)
GLFW (window creation)
Main.cpp
#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <vector>
#include "Graphics.h"
using namespace std;
using namespace glm;
struct DebugUserParams {
bool ShowNotifications = true;
} debuguserparams;
Camera camera;
void error_callback(int error, const char* description)
{
cout << "GLFW Error: " << description << endl;
cin.get();
}
void drop_callback(GLFWwindow* window, int pathcount, const char** paths)
{
for (unsigned int i = 0; i < pathcount; i++)
cout << "dropped file: " << paths[i] << endl;
}
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
Graphics::ResizeFramebuffer(ivec2(width, height));
}
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if (action == GLFW_PRESS)
{
if (key == GLFW_KEY_ESCAPE)
{
}
}
}
void cursor_position_callback(GLFWwindow* window, double xpos, double ypos)
{
static double xpos_prev = xpos;
static double ypos_prev = ypos;
double dx = xpos - xpos_prev;
double dy = ypos - ypos_prev;
xpos_prev = xpos;
ypos_prev = ypos;
camera.Theta = camera.Theta + 0.01f * float(dx);
camera.Phi = clamp(camera.Phi + 0.01f * float(dy), -1.5f, +1.5f);
}
void mouse_button_callback(GLFWwindow* window, int button, int action, int mods)
{
if (action == GLFW_PRESS)
{
if (button == GLFW_MOUSE_BUTTON_RIGHT)
{
}
}
}
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
camera.Distance = clamp(camera.Distance + 0.3f * float(yoffset), 1.0f, 20.0f);
}
/* debug */
void APIENTRY OpenGLDebugCallback(
GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar* message, const void* userparam)
{
/* debug user params */
DebugUserParams* params = (DebugUserParams*)userparam;
/* filter out unnecessary warnings */
if (!params->ShowNotifications)
if (severity == GL_DEBUG_SEVERITY_NOTIFICATION)
return;
/* source */
string str_source;
if (source == GL_DEBUG_SOURCE_API) str_source = "API";
if (source == GL_DEBUG_SOURCE_WINDOW_SYSTEM) str_source = "Window System";
if (source == GL_DEBUG_SOURCE_SHADER_COMPILER) str_source = "Shader Compiler";
if (source == GL_DEBUG_SOURCE_THIRD_PARTY) str_source = "Third Party";
if (source == GL_DEBUG_SOURCE_APPLICATION) str_source = "Application";
if (source == GL_DEBUG_SOURCE_OTHER) str_source = "Other";
/* type */
string str_type;
if (type == GL_DEBUG_TYPE_ERROR) str_type = "Error";
if (type == GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR) str_type = "Deprecated Behavior";
if (type == GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR) str_type = "Undefined Behavior";
if (type == GL_DEBUG_TYPE_PORTABILITY) str_type = "Portability";
if (type == GL_DEBUG_TYPE_PERFORMANCE) str_type = "Performance";
if (type == GL_DEBUG_TYPE_MARKER) str_type = "Marker";
if (type == GL_DEBUG_TYPE_PUSH_GROUP) str_type = "Push Group";
if (type == GL_DEBUG_TYPE_POP_GROUP) str_type = "Pop Group";
if (type == GL_DEBUG_TYPE_OTHER) str_type = "Other";
/* severity */
string str_severity;
if (severity == GL_DEBUG_SEVERITY_HIGH) str_severity = "High";
if (severity == GL_DEBUG_SEVERITY_MEDIUM) str_severity = "Medium";
if (severity == GL_DEBUG_SEVERITY_LOW) str_severity = "Low";
if (severity == GL_DEBUG_SEVERITY_NOTIFICATION) str_severity = "Notification";
/* print message */
cout << "OpenGL Debug Message:" << endl;
cout << "----------------------------------" << endl;
cout << "ID: \t\t" << id << endl;
cout << "Source: \t" << str_source << endl;
cout << "Type: \t\t" << str_type << endl;
cout << "Severity: \t" << str_severity << endl;
cout << "Message: \t" << message << endl;
cout << "----------------------------------" << endl << endl;
}
/************************************************************************************/
int main(int argc, char* argv[])
{
bool fullscreen = false;
bool debugcontext = true;
bool compatibilityprofilecontext = false;
bool vsync = true;
/* Initialize GLFW */
if (!glfwInit())
return 1;
/* Create a window and its OpenGL context */
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
glfwWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, debugcontext ? GLFW_TRUE : GLFW_FALSE);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, compatibilityprofilecontext ? GLFW_TRUE : GLFW_FALSE);
glfwWindowHint(GLFW_OPENGL_PROFILE, compatibilityprofilecontext ? GLFW_OPENGL_COMPAT_PROFILE : GLFW_OPENGL_CORE_PROFILE);
GLFWmonitor* monitor = fullscreen ? glfwGetPrimaryMonitor() : NULL;
GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGL", monitor, NULL);
if (!window)
{
glfwTerminate();
return 1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
/* Set V-sync */
glfwSwapInterval(vsync ? 1 : 0);
/* Set callback functions */
glfwSetErrorCallback(error_callback);
glfwSetDropCallback(window, drop_callback);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
glfwSetKeyCallback(window, key_callback);
glfwSetCursorPosCallback(window, cursor_position_callback);
glfwSetMouseButtonCallback(window, mouse_button_callback);
glfwSetScrollCallback(window, scroll_callback);
/* Initialize GLEW */
if (glewInit() != GLEW_OK)
{
glfwTerminate();
return 2;
}
/* Register debug callback if debug context is available */
GLint contextflags = 0;
glGetIntegerv(GL_CONTEXT_FLAGS, &contextflags);
if (contextflags & GL_CONTEXT_FLAG_DEBUG_BIT)
{
glEnable(GL_DEBUG_OUTPUT);
glDebugMessageCallback(OpenGLDebugCallback, &debuguserparams);
}
/* Initialize graphics */
int width = 0, height = 0;
glfwGetFramebufferSize(window, &width, &height);
if (!Graphics::Initialize(ivec2(width, height)))
{
glfwTerminate();
cin.get();
return 3;
}
// setup example materials
//----------------------------------------
Material chrome;
chrome.SetKd(vec3(0.400f, 0.400f, 0.400f));
chrome.SetKs(vec3(0.774f, 0.774f, 0.774f));
chrome.Ns = 76.8f;
chrome.d = 1.0f;
Material gold;
gold.SetKd(vec3(0.751f, 0.606f, 0.226f));
gold.SetKs(vec3(0.628f, 0.556f, 0.366f));
gold.Ns = 51.2f;
gold.d = 1.0f;
//----------------------------------------
// setup example meshes
//----------------------------------------
Mesh cube;
cube.Vertices = {
// +x
{ { +0.5f, -0.5f, -0.5f }, { +1, 0, 0 }, { 0, 0 } },
{ { +0.5f, +0.5f, -0.5f }, { +1, 0, 0 }, { 0, 0 } },
{ { +0.5f, +0.5f, +0.5f }, { +1, 0, 0 }, { 0, 0 } },
{ { +0.5f, -0.5f, +0.5f }, { +1, 0, 0 }, { 0, 0 } },
// -x
{ { -0.5f, -0.5f, -0.5f }, { -1, 0, 0 }, { 0, 0 } },
{ { -0.5f, +0.5f, -0.5f }, { -1, 0, 0 }, { 0, 0 } },
{ { -0.5f, +0.5f, +0.5f }, { -1, 0, 0 }, { 0, 0 } },
{ { -0.5f, -0.5f, +0.5f }, { -1, 0, 0 }, { 0, 0 } },
// +y
{ { -0.5f, +0.5f, -0.5f }, { 0, +1, 0 }, { 0, 0 } },
{ { +0.5f, +0.5f, -0.5f }, { 0, +1, 0 }, { 0, 0 } },
{ { +0.5f, +0.5f, +0.5f }, { 0, +1, 0 }, { 0, 0 } },
{ { -0.5f, +0.5f, +0.5f }, { 0, +1, 0 }, { 0, 0 } },
// -y
{ { -0.5f, -0.5f, -0.5f }, { 0, -1, 0 }, { 0, 0 } },
{ { +0.5f, -0.5f, -0.5f }, { 0, -1, 0 }, { 0, 0 } },
{ { +0.5f, -0.5f, +0.5f }, { 0, -1, 0 }, { 0, 0 } },
{ { -0.5f, -0.5f, +0.5f }, { 0, -1, 0 }, { 0, 0 } },
// +z
{ { -0.5f, -0.5f, +0.5f }, { 0, 0, +1 }, { 0, 0 } },
{ { +0.5f, -0.5f, +0.5f }, { 0, 0, +1 }, { 0, 0 } },
{ { +0.5f, +0.5f, +0.5f }, { 0, 0, +1 }, { 0, 0 } },
{ { -0.5f, +0.5f, +0.5f }, { 0, 0, +1 }, { 0, 0 } },
// -z
{ { -0.5f, -0.5f, -0.5f }, { 0, 0, -1 }, { 0, 0 } },
{ { +0.5f, -0.5f, -0.5f }, { 0, 0, -1 }, { 0, 0 } },
{ { +0.5f, +0.5f, -0.5f }, { 0, 0, -1 }, { 0, 0 } },
{ { -0.5f, +0.5f, -0.5f }, { 0, 0, -1 }, { 0, 0 } },
};
cube.Faces = {
// +x
{ 0, 1, 2 },
{ 0, 2, 3 },
// -x
{ 4, 6, 5 },
{ 4, 7, 6 },
// +y
{ 8, 10, 9 },
{ 8, 11, 10 },
// -y
{ 12, 13, 14 },
{ 12, 14, 15 },
// +z
{ 16, 17, 18 },
{ 16, 18, 19 },
// -z
{ 20, 22, 21 },
{ 20, 23, 22 },
};
//----------------------------------------
// send materials and meshes to graphics
//----------------------------------------
int material_ref_chrome = Graphics::AddMaterial(chrome);
int material_ref_gold = Graphics::AddMaterial(gold);
int mesh_ref_cube = Graphics::AddMesh(cube);
//----------------------------------------
// setup array of example objects
//----------------------------------------
std::vector<Object> objects;
for (int x = -2; x <= 2; x++)
{
for (int y = -2; y <= 2; y++)
{
for (int z = -2; z <= 2; z++)
{
// create dummy object in scene
Object object;
// transform object to world-space
object.Transform =
translate(vec3(x * 1.5f, y * 1.5f, z * 1.5f));
// set material index that should be used for mesh
object.Material_Ref = material_ref_chrome;
if (abs(x) % 2)
object.Material_Ref = material_ref_gold;
// set mesh index that should be drawn for object
object.Mesh_Ref = mesh_ref_cube;
// put object into scene
objects.push_back(object);
}
}
}
//----------------------------------------
/* Loop until the user closes the window */
//----------------------------------------
while (!glfwWindowShouldClose(window))
{
/* draw objects */
Graphics::Render(camera, objects);
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
//----------------------------------------
/* Clean up graphics */
Graphics::CleanUp();
glfwTerminate();
return 0;
}
Shader.h
#pragma once
#define GLEW_STATIC
#include <GL/glew.h>
#include <string>
#include <list>
std::string LoadTextFile(const std::string& filepath);
std::string ShaderTypeName(GLuint shader);
bool CompileShader(GLuint shader, const std::string& sourcecode);
std::string ShaderInfoLog(GLuint shader);
bool LinkProgram(GLuint program, const std::list<GLuint>& shaderlist);
std::string ProgramInfoLog(GLuint program);
Shader.cpp
#include "Shader.h"
#include <iostream>
#include <fstream>
std::string LoadTextFile(const std::string& filepath)
{
std::string result(""), line;
std::fstream f(filepath.c_str(), std::ios::in);
while (f.good())
{
std::getline(f, line);
result += line + '\n';
}
return result;
}
std::string ShaderTypeName(GLuint shader)
{
if (glIsShader(shader))
{
GLint type = 0;
glGetShaderiv(shader, GL_SHADER_TYPE, &type);
if (type == GL_VERTEX_SHADER)
return "Vertex Shader";
if (type == GL_TESS_CONTROL_SHADER)
return "Tessellation Control Shader";
if (type == GL_TESS_EVALUATION_SHADER)
return "Tessellation Evaluation Shader";
if (type == GL_GEOMETRY_SHADER)
return "Geometry Shader";
if (type == GL_FRAGMENT_SHADER)
return "Fragment Shader";
if (type == GL_COMPUTE_SHADER)
return "Compute Shader";
}
return "invalid shader";
}
bool CompileShader(GLuint shader, const std::string& sourcecode)
{
if (!glIsShader(shader))
{
std::cout << "ERROR: shader compilation failed, no valid shader specified" << std::endl;
return false;
}
if (sourcecode.empty())
{
std::cout << "ERROR: shader compilation failed, no source code specified (" << ShaderTypeName(shader) << ")" << std::endl;
return false;
}
const char* sourcearray[] = { sourcecode.c_str() };
glShaderSource(shader, 1, sourcearray, NULL);
glCompileShader(shader);
// check compile status
GLint status = 0;
glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
// successfully compiled shader
if (status == GL_TRUE)
return true;
// show compile errors
std::cout << "ERROR: shader compilation failed (" << ShaderTypeName(shader) << ")" << std::endl << ShaderInfoLog(shader) << std::endl;
return false;
}
std::string ShaderInfoLog(GLuint shader)
{
if (glIsShader(shader))
{
GLint logsize = 0;
GLchar infolog[1024] = { 0 };
glGetShaderInfoLog(shader, 1024, &logsize, infolog);
return std::string(infolog);
}
return "invalid shader";
}
bool LinkProgram(GLuint program, const std::list<GLuint>& shaderlist)
{
if (!glIsProgram(program))
{
std::cout << "ERROR: shader linking failed, no valid program specified" << std::endl;
return false;
}
// attach all shaders to the program
for (std::list<GLuint>::const_iterator it = shaderlist.begin(); it != shaderlist.end(); it++)
{
if (glIsShader(*it))
glAttachShader(program, *it);
}
// link program
glLinkProgram(program);
// detach all shaders again
for (std::list<GLuint>::const_iterator it = shaderlist.begin(); it != shaderlist.end(); it++)
{
if (glIsShader(*it))
glDetachShader(program, *it);
}
GLint status = 0;
glGetProgramiv(program, GL_LINK_STATUS, &status);
// successfully linked program
if (status == GL_TRUE)
return true;
// show link errors
std::cout << "ERROR: shader linking failed" << std::endl << ProgramInfoLog(program) << std::endl;
return false;
}
std::string ProgramInfoLog(GLuint program)
{
if (glIsProgram(program))
{
GLint logsize = 0;
GLchar infolog[1024] = { 0 };
glGetProgramInfoLog(program, 1024, &logsize, infolog);
return std::string(infolog);
}
return "invalid program";
}
Graphics.h
#pragma once
#define GLEW_STATIC
#include <GL/glew.h>
#define GLM_ENABLE_EXPERIMENTAL
#include <glm/gtc/type_ptr.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtx/transform.hpp>
#include <vector>
#include "Shader.h"
struct Material
{
unsigned int Kd = 0;
unsigned int Ks = 0;
float Ns = 0.0f;
float d = 0.0f;
void SetKd(const glm::vec3& kd) {
Kd = glm::packUnorm4x8(glm::vec4(kd.x, kd.y, kd.z, 0));
}
void SetKs(const glm::vec3& ks) {
Ks = glm::packUnorm4x8(glm::vec4(ks.x, ks.y, ks.z, 0));
}
};
struct Vertex
{
glm::vec3 Position = { 0, 0, 0 };
glm::vec3 Normal = { 0, 0, 0 };
glm::vec2 Texcoord = { 0, 0 };
};
struct Mesh
{
std::vector<Vertex> Vertices;
std::vector<glm::uvec3> Faces;
};
struct Object
{
glm::mat4 Transform = glm::mat4(1);
unsigned int Mesh_Ref = 0;
unsigned int Material_Ref = 0;
};
struct Camera
{
float Distance = 15.0f;
float Theta = 0.0f;
float Phi = 0.3f;
float FieldOfView = 1.57f;
float ZNear = 0.1f;
float ZFar = 100.0f;
glm::vec3 Position() const {
return glm::vec3(
Distance * cos(Phi) * cos(Theta),
Distance * sin(Phi),
Distance * cos(Phi) * sin(Theta));
}
glm::mat4 View() const {
return glm::lookAt(Position(), glm::vec3(0, 0, 0), glm::vec3(0, 1, 0));
}
glm::mat4 Projection(float aspect_ratio) const {
return glm::perspective(FieldOfView, aspect_ratio, ZNear, ZFar);
}
};
namespace Graphics
{
bool Initialize(const glm::ivec2 framebuffer_size);
void CleanUp();
void Render(const Camera& camera, const std::vector<Object>& objects);
void ResizeFramebuffer(const glm::ivec2 framebuffer_size);
int AddMaterial(const Material& material);
int AddMesh(const Mesh& mesh);
}
Graphics.cpp
#include "Graphics.h"
#include <iostream>
#define CheckForGLErrors CheckForGLErrors__(__FILE__, __LINE__)
using namespace std;
using namespace glm;
/* argument type buffered in GL_DRAW_INDIRECT_BUFFER */
struct DrawElementsIndirectCommand
{
GLuint Count = 0;
GLuint InstanceCount = 0;
GLuint FirstIndex = 0;
GLuint BaseVertex = 0;
GLuint BaseInstance = 0;
};
/* sub-struct containing the values for a specific mesh */
struct MeshRef
{
GLuint BaseVertex = 0;
GLuint BaseIndex = 0;
GLuint IndexCount = 0;
};
GLuint program = 0;
GLuint vertexshader = 0;
GLuint fragmentshader = 0;
GLuint vertexarray = 0;
GLuint vertexbuffer = 0;
GLuint indexbuffer = 0;
GLuint instancebuffer = 0;
GLuint indirectbuffer = 0;
GLuint materialbuffer = 0;
GLuint materialindicesbuffer = 0;
vector<Vertex> vertices;
vector<GLuint> indices;
vector<MeshRef> mesh_references;
vector<Material> materials;
bool reload_mesh_buffers = true;
bool reload_material_buffers = true;
void CheckForGLErrors__(const char* file, unsigned int line)
{
string errorstring;
for (GLenum error; (error = glGetError()) != GL_NO_ERROR;)
{
if (error == GL_INVALID_ENUM)
errorstring += " GL_INVALID_ENUM";
if (error == GL_INVALID_VALUE)
errorstring += " GL_INVALID_VALUE";
if (error == GL_INVALID_OPERATION)
errorstring += " GL_INVALID_OPERATION";
if (error == GL_STACK_OVERFLOW)
errorstring += " GL_STACK_OVERFLOW";
if (error == GL_STACK_UNDERFLOW)
errorstring += " GL_STACK_UNDERFLOW";
if (error == GL_OUT_OF_MEMORY)
errorstring += " GL_OUT_OF_MEMORY";
if (error == GL_INVALID_FRAMEBUFFER_OPERATION)
errorstring += " GL_INVALID_FRAMEBUFFER_OPERATION";
if (error == GL_CONTEXT_LOST)
errorstring += " GL_CONTEXT_LOST";
}
if (!errorstring.empty())
{
cout
<< (char)7
<< "OpenGL Error: " << endl
<< "\tLine: \t" << line << endl
<< "\tFile: \t" << file << endl
<< "\tErrors: \t" << errorstring << endl << endl;
cin.get();
}
}
void ReloadMaterialBuffer()
{
if (!reload_material_buffers)
return;
reload_material_buffers = false;
// fill material buffer
glNamedBufferData(
materialbuffer,
materials.size() * sizeof(Material),
materials.data(),
GL_DYNAMIC_DRAW);
}
void ReloadMeshBuffers()
{
if (!reload_mesh_buffers)
return;
reload_mesh_buffers = false;
// fill vertex buffer
glNamedBufferData(
vertexbuffer,
vertices.size() * sizeof(Vertex),
vertices.data(),
GL_DYNAMIC_DRAW);
// fill index buffer
glNamedBufferData(
indexbuffer,
indices.size() * sizeof(GLuint),
indices.data(),
GL_DYNAMIC_DRAW);
}
bool Graphics::Initialize(const glm::ivec2 framebuffer_size)
{
// create GL objects
//----------------------------------------
program = glCreateProgram();
vertexshader = glCreateShader(GL_VERTEX_SHADER);
fragmentshader = glCreateShader(GL_FRAGMENT_SHADER);
glCreateVertexArrays(1, &vertexarray);
glCreateBuffers(1, &vertexbuffer);
glCreateBuffers(1, &indexbuffer);
glCreateBuffers(1, &instancebuffer);
glCreateBuffers(1, &indirectbuffer);
glCreateBuffers(1, &materialbuffer);
glCreateBuffers(1, &materialindicesbuffer);
//----------------------------------------
// setup program
//----------------------------------------
if (!CompileShader(vertexshader, LoadTextFile("vs.glsl")))
return false;
if (!CompileShader(fragmentshader, LoadTextFile("fs.glsl")))
return false;
if (!LinkProgram(program, { vertexshader, fragmentshader }))
return false;
//----------------------------------------
// setup vertexarray
//----------------------------------------
// index buffer
glVertexArrayElementBuffer(vertexarray, indexbuffer);
// per-vertex attributes
glVertexArrayAttribFormat(vertexarray, 0, 3, GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribFormat(vertexarray, 1, 3, GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribFormat(vertexarray, 2, 2, GL_FLOAT, GL_FALSE, 0);
glVertexArrayVertexBuffer(vertexarray, 0, vertexbuffer, offsetof(Vertex, Position), sizeof(Vertex));
glVertexArrayVertexBuffer(vertexarray, 1, vertexbuffer, offsetof(Vertex, Normal), sizeof(Vertex));
glVertexArrayVertexBuffer(vertexarray, 2, vertexbuffer, offsetof(Vertex, Texcoord), sizeof(Vertex));
glEnableVertexArrayAttrib(vertexarray, 0);
glEnableVertexArrayAttrib(vertexarray, 1);
glEnableVertexArrayAttrib(vertexarray, 2);
// per-instance attributes
glVertexArrayAttribFormat(vertexarray, 3, 4, GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribFormat(vertexarray, 4, 4, GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribFormat(vertexarray, 5, 4, GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribFormat(vertexarray, 6, 4, GL_FLOAT, GL_FALSE, 0);
glVertexArrayVertexBuffer(vertexarray, 3, instancebuffer, sizeof(vec4) * 0, sizeof(mat4));
glVertexArrayVertexBuffer(vertexarray, 4, instancebuffer, sizeof(vec4) * 1, sizeof(mat4));
glVertexArrayVertexBuffer(vertexarray, 5, instancebuffer, sizeof(vec4) * 2, sizeof(mat4));
glVertexArrayVertexBuffer(vertexarray, 6, instancebuffer, sizeof(vec4) * 3, sizeof(mat4));
glEnableVertexArrayAttrib(vertexarray, 3);
glEnableVertexArrayAttrib(vertexarray, 4);
glEnableVertexArrayAttrib(vertexarray, 5);
glEnableVertexArrayAttrib(vertexarray, 6);
glVertexArrayBindingDivisor(vertexarray, 3, 1);
glVertexArrayBindingDivisor(vertexarray, 4, 1);
glVertexArrayBindingDivisor(vertexarray, 5, 1);
glVertexArrayBindingDivisor(vertexarray, 6, 1);
//----------------------------------------
// SSBO bindings
//----------------------------------------
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, materialbuffer);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, materialindicesbuffer);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, 0);
//----------------------------------------
// resize framebuffer
//----------------------------------------
ResizeFramebuffer(framebuffer_size);
//----------------------------------------
CheckForGLErrors;
return true;
}
void Graphics::CleanUp()
{
// destroy GL objects
//----------------------------------------
glDeleteProgram(program);
glDeleteShader(vertexshader);
glDeleteShader(fragmentshader);
glDeleteVertexArrays(1, &vertexarray);
glDeleteBuffers(1, &vertexbuffer);
glDeleteBuffers(1, &indexbuffer);
glDeleteBuffers(1, &instancebuffer);
glDeleteBuffers(1, &indirectbuffer);
glDeleteBuffers(1, &materialbuffer);
glDeleteBuffers(1, &materialindicesbuffer);
//----------------------------------------
CheckForGLErrors;
}
void Graphics::Render(const Camera& camera, const std::vector<Object>& objects)
{
// make sure all materials are stored in material buffer
ReloadMaterialBuffer();
// make sure all meshes are stored in vertex buffer and index buffer
ReloadMeshBuffers();
// camera matrices
//----------------------------------------
float aspect_ratio = 1.33f;
mat4 view = camera.View();
mat4 projection = camera.Projection(aspect_ratio);
//----------------------------------------
// calculate modelview matrices and draw commands
//----------------------------------------
// model-view transforms for instance buffer
vector<mat4> mvs;
// draw command parameters for indirect buffer
vector<DrawElementsIndirectCommand> cmds;
// indices for material indices buffer (SSBO)
vector<unsigned int> materialindices;
for (int i = 0; i < objects.size(); i++)
{
const auto& object = objects.at(i);
// modelview
mat4 mv = view * object.Transform;
// cmd
DrawElementsIndirectCommand cmd;
cmd.Count = mesh_references.at(object.Mesh_Ref).IndexCount;
cmd.InstanceCount = 1;
cmd.FirstIndex = mesh_references.at(object.Mesh_Ref).BaseIndex;
cmd.BaseVertex = mesh_references.at(object.Mesh_Ref).BaseVertex;
cmd.BaseInstance = i;
mvs.push_back(mv);
cmds.push_back(cmd);
materialindices.push_back(object.Material_Ref);
}
// fill instance buffer with modelview matrices
glNamedBufferData(
instancebuffer,
mvs.size() * sizeof(mat4),
mvs.data(),
GL_DYNAMIC_DRAW);
// fill indirect buffer with draw command parameters
glNamedBufferData(
indirectbuffer,
cmds.size() * sizeof(DrawElementsIndirectCommand),
cmds.data(),
GL_DYNAMIC_DRAW);
// fill material indices buffer
glNamedBufferData(
materialindicesbuffer,
materialindices.size() * sizeof(unsigned int),
materialindices.data(),
GL_DYNAMIC_DRAW);
int instance_count = cmds.size();
//----------------------------------------
// light parameters
//----------------------------------------
static float angle = 0;
angle += 0.016f * 3.141592654f / 4;
vec3 light_intensity = vec3(1, 1, 1);
vec3 light_direction = vec3(0.3f * cos(angle), -1.0f, 0.3f * sin(angle));
float light_ambient = 0.3f;
vec3 light_direction_eyespace = view * vec4(light_direction, 0);
//----------------------------------------
// clear screen
glClearColor(0.2f, 0.4f, 0.6f, 0.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
glEnable(GL_CULL_FACE);
glUseProgram(program);
glBindVertexArray(vertexarray);
glUniformMatrix4fv(0, 1, false, value_ptr(projection));
glUniform3fv(4, 1, value_ptr(light_intensity));
glUniform3fv(5, 1, value_ptr(light_direction_eyespace));
glUniform1f(6, light_ambient);
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, indirectbuffer);
// one draw call, rendering all the draw commands contained in "indirectbuffer"
glMultiDrawElementsIndirect(
GL_TRIANGLES,
GL_UNSIGNED_INT,
nullptr,
instance_count,
sizeof(DrawElementsIndirectCommand));
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, 0);
glBindVertexArray(0);
glUseProgram(0);
glDisable(GL_DEPTH_TEST);
glDisable(GL_CULL_FACE);
CheckForGLErrors;
}
void Graphics::ResizeFramebuffer(const glm::ivec2 framebuffer_size)
{
glViewport(0, 0, framebuffer_size.x, framebuffer_size.y);
}
int Graphics::AddMaterial(const Material& material)
{
// reload materials next frame
reload_material_buffers = true;
materials.push_back(material);
return materials.size() - 1;
}
int Graphics::AddMesh(const Mesh& mesh)
{
// reload mesh data next frame
reload_mesh_buffers = true;
// store vertex and index offset as well as index count of mesh
MeshRef mesh_reference;
mesh_reference.BaseVertex = vertices.size();
mesh_reference.BaseIndex = indices.size();
mesh_reference.IndexCount = mesh.Faces.size() * 3;
mesh_references.push_back(mesh_reference);
// collect vertices for vertex buffer (containing all meshes)
vertices.insert(vertices.end(), mesh.Vertices.begin(), mesh.Vertices.end());
// collect indices for index buffer (containing all meshes)
for (auto& face : mesh.Faces)
{
indices.push_back(face.x);
indices.push_back(face.y);
indices.push_back(face.z);
}
// return array index as "mesh reference"
return mesh_references.size() - 1;
}
Vertexshader: "vs.glsl"
#version 460 core
// camera perspective
layout (location = 0) uniform mat4 projection = mat4(1);
// per-vertex attributes
layout (location = 0) in vec3 in_position;
layout (location = 1) in vec3 in_normal;
layout (location = 2) in vec2 in_texcoord;
// per-instance attributes
layout (location = 3) in mat4 in_mv;
// interface vertex shader --> fragment shader
out VS_FS {
smooth vec3 position;
smooth vec3 normal;
smooth vec2 texcoord;
flat uint drawID;
} vs_out;
void main()
{
// vertex position
gl_Position = projection * in_mv * vec4(in_position, 1);
// position and normal in eye-space
vs_out.position = (in_mv * vec4(in_position, 1)).xyz;
vs_out.normal = (in_mv * vec4(in_normal, 0)).xyz;
// texture coordinate
vs_out.texcoord = in_texcoord;
// draw command index [ 0 ; instancecount )
vs_out.drawID = gl_DrawID;
}
Fragmentshader: "fs.glsl"
#version 460 core
// material definition
struct Material {
uint Kd;
uint Ks;
float Ns;
float d;
};
// array containing all materials
layout (std430, binding = 1) buffer MaterialBlock {
Material materials[];
};
// array containing material index for current draw command (size = instancecount)
layout (std430, binding = 2) buffer MaterialIndicesBlock {
uint material_indices[];
};
// light parameters
layout (location = 4) uniform vec3 light_intensity = vec3(0, 0, 0);
layout (location = 5) uniform vec3 light_direction = vec3(0, 0, 0);
layout (location = 6) uniform float light_ambient = 0.0f;
// interface vertex shader --> fragment shader
in VS_FS {
smooth vec3 position;
smooth vec3 normal;
smooth vec2 texcoord;
flat uint drawID;
} fs_in;
// fragment color
layout (location = 0) out vec4 out_color;
void main()
{
// get material index
uint material_index = material_indices[fs_in.drawID];
// get material data
vec3 Kd = unpackUnorm4x8(materials[material_index].Kd).rgb;
vec3 Ks = unpackUnorm4x8(materials[material_index].Ks).rgb;
float Ns = clamp(materials[material_index].Ns, 1, 1000);
float d = clamp(materials[material_index].d, 0, 1);
// directions (eye-space)
vec3 N = normalize(fs_in.normal);
vec3 L = normalize(-light_direction);
vec3 R = reflect(-L, N);
vec3 V = normalize(-fs_in.position);
// light data
vec3 Ia = light_intensity * clamp(light_ambient, 0, 1);
vec3 Id = light_intensity * max(0, dot(N, L));
vec3 Is = light_intensity * max(0, pow(max(0, dot(R, V)), Ns));
// color
vec3 color = (Ia + Id) * Kd + Is * Ks;
// to framebuffer
out_color = vec4(color, d);
}
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