In the same vein, I have getting nothing on the screen when there should
be rendered a red triangle. The vertex positions are those used by
McKeeson http://www.arcsynthesis.org/gltut/, being in ndc fall within
the frustum. The code for setting up vao and shaders is:
module ShaderHub;
import std.stdio;
import std.string;
import derelict.opengl3.gl3;
class ShaderHub{
private bool ok=true;
private GLuint shad=0, vshad=0, fshad=0;
private int voff=0;
private GLuint vbo=0, vao=0;
const float[] v = [ 0.75f, 0.75f, 0.0f, 1.0f,
0.75f, -0.75f, 0.0f, 1.0f,
-0.75f, -0.75f, 0.0f, 1.0f];
public this(){
immutable string vshader = `
#version 330
layout(location = 1) in vec4 pos;
void main(void)
{
gl_Position = pos;
}
`;
immutable string fshader = `
#version 330
void main(void)
{
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
`;
shad=glCreateProgram();
if(shad==0){
writeln("Error: GL did not assigh main shader program id");
ok=false;
}
vshad=glCreateShader(GL_VERTEX_SHADER);
const char *vptr=toStringz(vshader);
glShaderSource(vshad, 1, &vptr, null);
glCompileShader(vshad);
int status, len;
glGetShaderiv(vshad, GL_COMPILE_STATUS, &status);
if(status==GL_FALSE){
glGetShaderiv(vshad, GL_INFO_LOG_LENGTH, &len);
char[] error=new char[len];
glGetShaderInfoLog(vshad, len, null, cast(char*)error);
writeln(error);
ok=false;
}
fshad=glCreateShader(GL_FRAGMENT_SHADER);
const char *fptr=toStringz(fshader);
glShaderSource(fshad, 1, &fptr, null);
glCompileShader(fshad);
glGetShaderiv(vshad, GL_COMPILE_STATUS, &status);
if(status==GL_FALSE){
glGetShaderiv(fshad, GL_INFO_LOG_LENGTH, &len);
char[] error=new char[len];
glGetShaderInfoLog(fshad, len, null, cast(char*)error);
writeln(error);
ok=false;
}
glAttachShader(shad, vshad);
glAttachShader(shad, fshad);
glLinkProgram(shad);
glGetShaderiv(shad, GL_LINK_STATUS, &status);
if(status==GL_FALSE){
glGetShaderiv(shad, GL_INFO_LOG_LENGTH, &len);
char[] error=new char[len];
glGetShaderInfoLog(shad, len, null, cast(char*)error);
writeln(error);
ok=false;
}
glGenVertexArrays(1, &vao);
if(vao<1){
writeln("Error: GL failed to assign vao id");
ok=false;
}
glBindVertexArray(vao);
glGenBuffers(1, &vbo);
if(vbo<1){
writeln("Error: GL failed to assign vbo id");
ok=false;
}
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, v.length * GL_FLOAT.sizeof, &v[0],
GL_STATIC_DRAW);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, cast(void*)voff);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
public void draw(){
glUseProgram(shad);
writeln(glGetAttribLocation(shad, "pos"));//prints 1
glBindVertexArray(vao);
glDrawArrays(GL_TRIANGLES, 0, 6);
glBindVertexArray(0);
glUseProgram(0);
}
}
//__________________________________________________________________
the code for setting up openGL3 is:
import std.stdio;
import derelict.sdl2.sdl;
import derelict.opengl3.gl3;
import EventHub;
import ExposeApp;
pragma(lib, "DerelictUtil.lib");
pragma(lib, "DerelictSDL2.lib");
pragma(lib, "DerelictGL3.lib");
class App{
private ExposeApp funcPtrs;
private EventHub ehub;
private SDL_Window *win;
private SDL_GLContext context;
private int w=600, h=480, fov=55;
private bool running=true;
public this(){
if(!initSDL()){
writeln("Error initializing SDL");
SDL_Quit();
}
initGL();
funcPtrs=new ExposeApp();
funcPtrs.stop=&stopLoop;
funcPtrs.grabMouse=&grabMouse;
funcPtrs.releaseMouse=&releaseMouse;
ehub=new EventHub(funcPtrs);
while(running){
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
ehub.tick();
SDL_GL_SwapWindow(win);
}
SDL_GL_DeleteContext(context);
SDL_DestroyWindow(win);
SDL_Quit();
}
private void stopLoop(){
running=false;
}
private void grabMouse(){
SDL_ShowCursor(SDL_DISABLE);
SDL_SetWindowGrab(win, SDL_TRUE);
}
private void releaseMouse(){
SDL_ShowCursor(SDL_ENABLE);
SDL_SetWindowGrab(win, SDL_FALSE);
}
private bool initSDL(){
if(SDL_Init(SDL_INIT_VIDEO)< 0){
writefln("Error initializing SDL");
SDL_Quit();
return false;
}
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
win=SDL_CreateWindow("3Doodle", SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED, w, h, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
if(!win){
writefln("Error creating SDL window");
SDL_Quit();
return false;
}
context=SDL_GL_CreateContext(win);
SDL_GL_SetSwapInterval(1);
DerelictGL3.reload();
return true;
}
private void initGL(){
resize(w, h);
glEnable(GL_DEPTH_TEST);
glEnable(GL_CULL_FACE);
glDepthFunc(GL_LEQUAL);
glClearColor(0.0, 0.0, 0.0, 1.0);
glClearDepth(1.0);
glCullFace(GL_BACK);
glFrontFace(GL_CCW);
}
private void resize(int w, int h){
//this will contain the makings of the projection matrix, which we go
into next tut
glViewport(0, 0, w, h);
}
}
void main(){
try{
DerelictSDL2.load();
}catch(Exception e){
writeln("Error loading SDL2 lib");
}
try{
DerelictGL3.load();
}catch(Exception e){
writeln("Error loading GL3 lib");
}
App a=new App();
}
Any help would be great.
