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alex1997

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About alex1997

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  1. Man, I'm targetting drawin 2d, no bunny object, not fancy cubes, wanna draw 2d rectangles with custom shaders effeciently and after that to implement functionality on them... my 3cents..
  2. I'm currently learning opengl and started to make my own 2D engine. So far I've managed to render an rectangle made out of 2 triangles with `glDrawElements()` and apply it a custom shader. This is how my code looks like so far: #include <all> int main() { Window window("OpenGL", 800, 600); Shader shader1("./file.shader"); float vt[8] = { -0.5f, -0.5f, 0.5f, -0.5f, 0.5f, 0.5f, -0.5f, 0.5f }; const GLuint indices[6] = { 0, 1, 2, 2, 3, 0 }; GLuint vao, vbo, ebo; glGenVertexArrays(1, &vao); glBindVertexArray(vao); glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(vt), vertices, GL_STATIC_DRAW); glEnableVertexAttribArray(0); glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0); glGenBuffers(1, &ebo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW); while(window.isOpen()) { window.clear(0.0, 0.5, 1.0); shader1.use(); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, NULL); window.update(); } glDeleteBuffers(1, &vbo); glDeleteBuffers(1, &ebo); glDeleteVertexArrays(1, &vao); return 0; } There multiple way to do it, but I've heard that drawing and switching shaders one by one is pretty expensive. I'm looking to preload all the data, vertices, shaders in one buffer or what's more efficient and when it's all ready start drawing them in one call, similar to a batch. Thanks!
  3. Thanks! I've pasted my code above And yes, beofre rendering wanna attach the shader and when the objects are ready draw them.
  4. I'm looking to render multiple objects (rectangles) with different shaders. So far I've managed to render one rectangle made out of 2 triangles and apply shader to it, but when it comes to render another I get stucked. Searched for documentations or stuffs that could help me, but everything shows how to render only 1 object. Any tips or help is highly appreciated, thanks! Here's my code for rendering one object with shader! #define GLEW_STATIC #include <stdio.h> #include <GL/glew.h> #include <GLFW/glfw3.h> #include "window.h" #define GLSL(src) "#version 330 core\n" #src // #define ASSERT(expression, msg) if(expression) {fprintf(stderr, "Error on line %d: %s\n", __LINE__, msg);return -1;} int main() { // Init GLFW if (glfwInit() != GL_TRUE) { std::cerr << "Failed to initialize GLFW\n" << std::endl; exit(EXIT_FAILURE); } // Create a rendering window with OpenGL 3.2 context glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); glfwWindowHint(GLFW_RESIZABLE, GL_FALSE); // assing window pointer GLFWwindow *window = glfwCreateWindow(800, 600, "OpenGL", NULL, NULL); glfwMakeContextCurrent(window); // Init GLEW glewExperimental = GL_TRUE; if (glewInit() != GLEW_OK) { std::cerr << "Failed to initialize GLEW\n" << std::endl; exit(EXIT_FAILURE); } // ----------------------------- RESOURCES ----------------------------- // // create gl data const GLfloat positions[8] = { -0.5f, -0.5f, 0.5f, -0.5f, 0.5f, 0.5f, -0.5f, 0.5f, }; const GLuint elements[6] = { 0, 1, 2, 2, 3, 0 }; // Create Vertex Array Object GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); // Create a Vertex Buffer Object and copy the vertex data to it GLuint vbo; glGenBuffers(1, &vbo); glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW); // Specify the layout of the vertex data glEnableVertexAttribArray(0); // layout(location = 0) glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, 0); // Create a Elements Buffer Object and copy the elements data to it GLuint ebo; glGenBuffers(1, &ebo); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elements), elements, GL_STATIC_DRAW); // Create and compile the vertex shader const GLchar *vertexSource = GLSL( layout(location = 0) in vec2 position; void main() { gl_Position = vec4(position, 0.0, 1.0); } ); GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER); glShaderSource(vertexShader, 1, &vertexSource, NULL); glCompileShader(vertexShader); // Create and compile the fragment shader const char* fragmentSource = GLSL( out vec4 gl_FragColor; uniform vec2 u_resolution; void main() { vec2 pos = gl_FragCoord.xy / u_resolution; gl_FragColor = vec4(1.0); } ); GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(fragmentShader, 1, &fragmentSource, NULL); glCompileShader(fragmentShader); // Link the vertex and fragment shader into a shader program GLuint shaderProgram = glCreateProgram(); glAttachShader(shaderProgram, vertexShader); glAttachShader(shaderProgram, fragmentShader); glLinkProgram(shaderProgram); glUseProgram(shaderProgram); // get uniform's id by name and set value GLint uRes = glGetUniformLocation(shaderProgram, "u_Resolution"); glUniform2f(uRes, 800.0f, 600.0f); // ---------------------------- RENDERING ------------------------------ // while(!glfwWindowShouldClose(window)) { // Clear the screen to black glClear(GL_COLOR_BUFFER_BIT); glClearColor(0.0f, 0.5f, 1.0f, 1.0f); // Draw a rectangle made of 2 triangles -> 6 vertices glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, NULL); // Swap buffers and poll window events glfwSwapBuffers(window); glfwPollEvents(); } // ---------------------------- CLEARING ------------------------------ // // Delete allocated resources glDeleteProgram(shaderProgram); glDeleteShader(fragmentShader); glDeleteShader(vertexShader); glDeleteBuffers(1, &vbo); glDeleteVertexArrays(1, &vao); return 0; }
  5. Hey, I've a minor problem that prevents me from moving forward with development and looking to find a way that could solve it. Overall, I'm having a sf::VertexArray object and looking to reander a shader inside its area. The problem is that the shader takes the window as canvas and only becomes visible in the object range which is not what I'm looking for.. Here's a stackoverflow links that shows the expected behaviour image. Any tips or help is really appreciated. I would have accepted that answer, but currently it does not work with #version 330 ...
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