Rendering a simple rectangle with OpenGL 3 in D language - d

Question

I'm going insane because I can't make a simple set of triangles appear in my screen.
I'm using OpenGL3 (without the deprecated fixed pipeline) using the derelict bindings for the D programming language.
Can you spot the error in the following program? It compiles just fine and doesn't throw any OpenGL/GLSL error. It just shows a blank screen with the clear color I set.
import std.string;
import std.conv;
import derelict.opengl3.gl3;
import derelict.sdl2.sdl2;
immutable string minimalVertexShader = `
#version 120
attribute vec2 position;
void main(void)
{
gl_Position = vec4(position, 0, 1);
}
`;
immutable string minimalFragmentShader = `
#version 120
void main(void)
{
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
`;
void main() {
DerelictSDL2.load();
DerelictGL3.load();
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
throw new Exception("Failed to initialize SDL: " ~ to!string(SDL_GetError()));
}
// Set OpenGL version
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
// Set OpenGL attributes
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
auto sdlwindow = SDL_CreateWindow("D App",
SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
640, 480, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
if (!sdlwindow)
throw new Exception("Failed to create a SDL window: " ~ to!string(SDL_GetError()));
SDL_GL_CreateContext(sdlwindow);
DerelictGL3.reload();
float[] vertices = [ -1, -1, 1, -1, -1, 1, 1, 1];
ushort[] indices = [0, 1, 2, 3];
uint vbo, ibo;
// Create VBO
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, vertices.sizeof, vertices.ptr, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
// Create IBO
glGenBuffers(1, &ibo);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.sizeof, indices.ptr, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
// Program
auto program = glCreateProgram();
// Vertex Shader
auto vsh = glCreateShader(GL_VERTEX_SHADER);
auto vshSrc = minimalVertexShader.toStringz;
glShaderSource(vsh, 1, &vshSrc, null);
glCompileShader(vsh);
glAttachShader(program, vsh);
// Fragment Shader
auto fsh = glCreateShader(GL_FRAGMENT_SHADER);
auto fshSrc = minimalFragmentShader.toStringz;
glShaderSource(fsh, 1, &fshSrc, null);
glCompileShader(fsh);
glAttachShader(program, fsh);
glLinkProgram(program);
glUseProgram(program);
auto position = glGetAttribLocation(program, "position");
auto run = true;
while (run) {
SDL_Event event;
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
run = false;
default:
break;
}
}
glClearColor(1, 0.9, 0.8, 1);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glEnableVertexAttribArray(position);
glVertexAttribPointer(position, 2, GL_FLOAT, GL_FALSE, vertices.sizeof, null);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
glDrawElements(GL_TRIANGLE_STRIP, 4, GL_UNSIGNED_SHORT, null);
glDisableVertexAttribArray(position);
SDL_GL_SwapWindow(sdlwindow);
}
}

Answer 1

On this line:
glVertexAttribPointer(position, 2, GL_FLOAT, GL_FALSE, vertices.sizeof, null);
are you sure that you want vertices.sizeof, which has a value of 16? In D, a dynamic array is a struct with two members (ptr and length). You probably want either float.sizeof or float.sizeof * 2.
And the same goes for your BufferData calls.