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#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <Helpers.h>
#include <iostream>
#include <vector>
void error_callback(int error, const char* description)
{
std::cerr << "Error: " << description << std::endl;
}
int main()
{
unsigned int bufferWidth = 6304;
unsigned int bufferHeight = 1773;
unsigned int windowWidth = 1600;
unsigned int windowHeight = 900;
unsigned int orbitLengthRed = 10;
unsigned int orbitLengthGreen = 100;
unsigned int orbitLengthBlue = 1000;
unsigned int localWorkgroupSizeX = 1024;
unsigned int localWorkgroupSizeY = 1;
unsigned int localWorkgroupSizeZ = 1;
unsigned int globalWorkGroupSizeX = 1024;
unsigned int globalWorkGroupSizeY = 1;
unsigned int globalWorkGroupSizeZ = 1;
double pngGamma = 1.0;
double pngColorScale = 2.0;
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
return -1;
glfwSetErrorCallback(error_callback);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(windowWidth, windowHeight, "Buddhabrot", NULL, NULL);
if (!window)
{
std::cerr << "Failed to create OpenGL 4.3 core context. We do not support compatibility contexts." << std::endl;
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
gladLoadGLLoader((GLADloadproc)glfwGetProcAddress);
//we have a context. Let's check if input is sane.
//calcualte buffer size, and make sure it's allowed by the driver.
const unsigned int pixelCount{(bufferWidth * bufferHeight)*3}; //*3 -> RGB
{
int maxSSBOSize;
glGetIntegerv(GL_MAX_SHADER_STORAGE_BLOCK_SIZE,&maxSSBOSize);
if(pixelCount * 4 > maxSSBOSize)
{
std::cout << "Requested buffer size larger than maximum allowed by graphics driver. Max pixel number: " << maxSSBOSize/12 << std::endl;
glfwTerminate();
return 0;
}
int WorkGroupSizeLimitX, WorkGroupSizeLimitY, WorkGroupSizeLimitZ;
glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT,0,&WorkGroupSizeLimitX);
glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT,1,&WorkGroupSizeLimitY);
glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT,2,&WorkGroupSizeLimitZ);
if(globalWorkGroupSizeX > WorkGroupSizeLimitX || globalWorkGroupSizeY > WorkGroupSizeLimitY || globalWorkGroupSizeZ > WorkGroupSizeLimitZ)
{
std::cout << "Requested global work group size exceeds maximum dimension. Limits: " << WorkGroupSizeLimitX << ", " << WorkGroupSizeLimitY << ", " << WorkGroupSizeLimitZ << std::endl;
glfwTerminate();
return 0;
}
glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE,0,&WorkGroupSizeLimitX);
glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE,1,&WorkGroupSizeLimitY);
glGetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE,2,&WorkGroupSizeLimitZ);
if(localWorkgroupSizeX > WorkGroupSizeLimitX || localWorkgroupSizeY > WorkGroupSizeLimitY || localWorkgroupSizeZ > WorkGroupSizeLimitZ)
{
std::cout << "Requested local work group size exceeds maximum dimension. Limits: " << WorkGroupSizeLimitX << ", " << WorkGroupSizeLimitY << ", " << WorkGroupSizeLimitZ << std::endl;
glfwTerminate();
return 0;
}
int maxInvocations;
glGetIntegerv(GL_MAX_COMPUTE_WORK_GROUP_INVOCATIONS,&maxInvocations);
if(localWorkgroupSizeX*localWorkgroupSizeY*localWorkgroupSizeZ > maxInvocations)
{
std::cout << "Requested local work group size exceeds maximum total count (Product of x*y*z dimensions). Limit: " << maxInvocations << std::endl;
glfwTerminate();
return 0;
}
}
GLuint VertexArrayID;
glGenVertexArrays(1, &VertexArrayID);
glBindVertexArray(VertexArrayID);
const GLfloat g_vertex_buffer_data[] = {
-1.0f, -1.0f, 0.0f,
1.0f, -1.0f, 0.0f,
-1.0f, 1.0f, 0.0f,
1.0f, 1.0f, 0.0f
};
GLuint vertexbuffer;
glGenBuffers(1, &vertexbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
GLuint drawBuffer;
glGenBuffers(1, &drawBuffer);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, drawBuffer);
{
glBufferData(GL_SHADER_STORAGE_BUFFER, 4 * pixelCount, nullptr, GL_DYNAMIC_COPY);
glClearBufferData(GL_SHADER_STORAGE_BUFFER,GL_R8,GL_RED,GL_UNSIGNED_INT,nullptr);
}
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, drawBuffer);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, 0);
// Create and compile our GLSL program from the shaders
GLuint VertexAndFragmentShaders = Helpers::LoadShaders("Shaders/BuddhaVertex.glsl", "Shaders/BuddhaFragment.glsl");
//Do the same for the compute shader:
GLuint ComputeShader = Helpers::LoadComputeShader("Shaders/BuddhaCompute.glsl", localWorkgroupSizeX, localWorkgroupSizeY, localWorkgroupSizeZ);
uint32_t iterationCount{0};
glUseProgram(ComputeShader);
GLint iterationCountUniformHandle = glGetUniformLocation(ComputeShader, "iterationCount");
GLint orbitLengthUniformHandle = glGetUniformLocation(ComputeShader, "orbitLength");
GLint widthUniformComputeHandle = glGetUniformLocation(ComputeShader, "width");
GLint heightUniformComputeHandle = glGetUniformLocation(ComputeShader, "height");
glUniform3ui(orbitLengthUniformHandle,orbitLengthRed,orbitLengthGreen,orbitLengthBlue);
glUniform1ui(widthUniformComputeHandle, bufferWidth);
glUniform1ui(heightUniformComputeHandle,bufferHeight);
glUseProgram(VertexAndFragmentShaders);
GLint widthUniformFragmentHandle = glGetUniformLocation(VertexAndFragmentShaders, "width");
GLint heightUniformFragmentHandle = glGetUniformLocation(VertexAndFragmentShaders, "height");
glUniform1ui(widthUniformFragmentHandle, bufferWidth);
glUniform1ui(heightUniformFragmentHandle,bufferHeight);
glClearColor(0.0f, 0.0f, 0.4f, 0.0f);
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
//let the compute shader do something
glUseProgram(ComputeShader);
//increase iterationCount, which is used for pseudo random generation
glUniform1ui(iterationCountUniformHandle,++iterationCount);
glDispatchCompute(globalWorkGroupSizeX, globalWorkGroupSizeY, globalWorkGroupSizeZ);
//before reading the values in the ssbo, we need a memory barrier:
glMemoryBarrier(GL_SHADER_STORAGE_BARRIER_BIT); //I hope this is the correct (and only required) bit
/* Render here */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(VertexAndFragmentShaders);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glVertexAttribPointer(
0, // attribute 0. No particular reason for 0, but must match the layout in the shader.
3, // size
GL_FLOAT, // type
GL_FALSE, // normalized?
0, // stride
(void*)0 // array buffer offset
);
// Draw the triangle strip!
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); // Triangle strip with 4 vertices -> quad.
glDisableVertexAttribArray(0);
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glMemoryBarrier(GL_ALL_BARRIER_BITS);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, drawBuffer);
{
std::vector<uint32_t> readBackBuffer(pixelCount);
glGetBufferSubData(GL_SHADER_STORAGE_BUFFER,0,4 * pixelCount,readBackBuffer.data());
Helpers::WriteOutputPNG(readBackBuffer,bufferWidth,bufferHeight, pngGamma, pngColorScale);
}
//a bit of cleanup
glDeleteBuffers(1,&vertexbuffer);
glDeleteBuffers(1,&drawBuffer);
glfwTerminate();
return 0;
}
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