所以我制作了一个基本的 OpenGL 应用程序，一切都很好，直到我实现了一个几何着色器。
我得到的错误是 在 Demo.exe 中的 0x6A67F00A (nvoglv32.dll) 处引发的异常：0xC0000005：访问冲突读取位置 0x00000000。
现在，我不知道着色器是否是导致问题的原因，但在我实现它之前它运行良好。
我做了一些谷歌搜索，似乎有很多不同的原因，其中许多与 VAO 有关，这些原因保持不变。
错误发生在glDrawArrays(GL_TRIANGLES, 0, 6);
这是我的 C++ 代码：
//--------------------------------------------------------------------------------------
// BTH - Stefan Petersson 2014.
//--------------------------------------------------------------------------------------
#include <windows.h>
#include <string>
#include <fstream>
#include <streambuf>
#include <gl/glew.h>
#include <gl/GL.h>
#include "glm/glm/glm.hpp"
#include "glm/glm/gtc/matrix_transform.hpp"
#include "glm/glm/gtc/type_ptr.hpp"
#pragma comment(lib, "opengl32.lib")
#pragma comment(lib, "glew32.lib")
using namespace std;
HWND InitWindow(HINSTANCE hInstance);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
HGLRC CreateOpenGLContext(HWND wndHandle);
GLuint gVertexBuffer = 0;
GLuint gVertexAttribute = 0;
GLuint gShaderProgram = 0;
//is bad but ok
glm::mat4 World = glm::mat4(1.0f);
glm::mat4 View;
glm::mat4 Projection;
//
#define BUFFER_OFFSET(i) ((char *)nullptr + (i))
void CreateMatrices() {
glm::mat4 View = glm::lookAt(
glm::vec3(0, 0, 3), // Camera is at (4,3,3), in World Space
glm::vec3(0, 0, 0), // and looks at the origin
glm::vec3(0, 1, 0) // Head is up (set to 0,-1,0 to look upside-down)
);
// Projection matrix : 45° Field of View, 4:3 ratio, display range : 0.1 unit <-> 100 units
glm::mat4 Projection = glm::perspective(glm::radians(45.0f), (float)640 / (float)480, 0.1f, 100.0f);
World = glm::rotate(World, 0.01f, glm::vec3(0, 1, 0));
glm::mat4 mvp = Projection * View * World;
GLuint MatrixID = glGetUniformLocation(gShaderProgram, "MVP");
glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &mvp[0][0]);
}
void CreateTriangleData()
{
// this is how we will structure the input data for the vertex shader
// every six floats, is one vertex.
struct TriangleVertex
{
float x, y, z;
float r, g, b;
};
// create the actual data in plane Z = 0
TriangleVertex triangleVertices[6] =
{
// pos and color for each vertex
//first triangle
{ -0.5f, 0.5f, -0.0f, 1.0f, 0.0f, 0.0f },
{ 0.5f, 0.5f, -0.0f, 0.0f, 1.0f, 0.0f },
{ 0.5f, -0.5f, -0.0f, 0.0f, 0.0f, 1.0f },
//second triangle
{ 0.5f, -0.5f, -0.0f, 0.0f, 0.0f, 1.0f },
{ -0.5f, -0.5f, -0.0f, 0.0f, 1.0f, 0.0f },
{ -0.5f, 0.5f, -0.0f, 1.0f, 0.0f, 0.0f }
};
// Vertex Array Object (VAO)
glGenVertexArrays(1, &gVertexAttribute);
// bind == enable
glBindVertexArray(gVertexAttribute);
// this activates the first and second attributes of this VAO
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
// create a vertex buffer object (VBO) id
glGenBuffers(1, &gVertexBuffer);
// Bind the buffer ID as an ARRAY_BUFFER
glBindBuffer(GL_ARRAY_BUFFER, gVertexBuffer);
// This "could" imply copying to the GPU, depending on what the driver wants to do...
glBufferData(GL_ARRAY_BUFFER, sizeof(triangleVertices), triangleVertices, GL_STATIC_DRAW);
// query where which slot corresponds to the input vertex_position in the Vertex Shader
GLuint vertexPos = glGetAttribLocation(gShaderProgram, "vertex_position");
// specify that: the vertex attribute "vertexPos", of 3 elements of type FLOAT, not normalized, with STRIDE != 0,
// starts at offset 0 of the gVertexBuffer (it is implicitly bound!)
glVertexAttribPointer(vertexPos, 3, GL_FLOAT, GL_FALSE, sizeof(TriangleVertex), BUFFER_OFFSET(0));
// query where which slot corresponds to the input vertex_color in the Vertex Shader
GLuint vertexColor = glGetAttribLocation(gShaderProgram, "vertex_color");
// specify that: the vertex attribute "vertex_color", of 3 elements of type FLOAT, not normalized, with STRIDE != 0,
// starts at offset (12 bytes) of the gVertexBuffer
glVertexAttribPointer(vertexColor, 3, GL_FLOAT, GL_FALSE, sizeof(TriangleVertex), BUFFER_OFFSET(sizeof(float) * 3));
}
void SetViewport()
{
glViewport(0, 0, 640, 480);
}
void CreateShaders()
{
//create vertex shader
GLuint vs = glCreateShader(GL_VERTEX_SHADER);
// open glsl file and put it in a string
ifstream shaderFile("VertexShader.glsl");
std::string shaderText((std::istreambuf_iterator<char>(shaderFile)), std::istreambuf_iterator<char>());
shaderFile.close();
// make a double pointer (only valid here)
const char* shaderTextPtr = shaderText.c_str();
// ask GL to load this
glShaderSource(vs, 1, &shaderTextPtr, nullptr);
// ask GL to compile it
glCompileShader(vs);
//create fragment shader | same process.
GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
shaderFile.open("Fragment.glsl");
shaderText.assign((std::istreambuf_iterator<char>(shaderFile)), std::istreambuf_iterator<char>());
shaderFile.close();
shaderTextPtr = shaderText.c_str();
glShaderSource(fs, 1, &shaderTextPtr, nullptr);
glCompileShader(fs);
///create geometry shader | same process.
GLuint gs = glCreateShader(GL_GEOMETRY_SHADER);
shaderFile.open("Geometry.glsl");
shaderText.assign((std::istreambuf_iterator<char>(shaderFile)), std::istreambuf_iterator<char>());
shaderFile.close();
shaderTextPtr = shaderText.c_str();
glShaderSource(gs, 1, &shaderTextPtr, nullptr);
glCompileShader(gs);
//link shader program (connect vs and ps)
gShaderProgram = glCreateProgram();
glAttachShader(gShaderProgram, fs);
glAttachShader(gShaderProgram, vs);
glAttachShader(gShaderProgram, gs);
glLinkProgram(gShaderProgram);
glUseProgram(gShaderProgram);
}
void Render()
{
CreateMatrices();
// set the color TO BE used
glClearColor(0.2, 0.2, 0.2, 1);
// use the color to clear the color buffer
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 6);
}
int WINAPI wWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow )
{
MSG msg = { 0 };
HWND wndHandle = InitWindow(hInstance); //1. Skapa fönster
if (wndHandle)
{
HDC hDC = GetDC(wndHandle);
HGLRC hRC = CreateOpenGLContext(wndHandle); //2. Skapa och koppla OpenGL context
glewInit(); //3. Initiera The OpenGL Extension Wrangler Library (GLEW)
CreateShaders();
SetViewport(); //4. Sätt viewport
CreateTriangleData(); //6. Definiera triangelvertiser, 7. Skapa vertex buffer object (VBO), 8.Skapa vertex array object (VAO)
ShowWindow(wndHandle, nCmdShow);
while (WM_QUIT != msg.message)
{
if (PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else
{
Render(); //9. Rendera
SwapBuffers(hDC); //10. Växla front- och back-buffer
}
}
wglMakeCurrent(NULL, NULL);
ReleaseDC(wndHandle, hDC);
wglDeleteContext(hRC);
DestroyWindow(wndHandle);
}
return (int) msg.wParam;
}
HWND InitWindow(HINSTANCE hInstance)
{
WNDCLASSEX wcex = { 0 };
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.hInstance = hInstance;
wcex.lpszClassName = L"BTH_GL_DEMO";
if( !RegisterClassEx(&wcex) )
return false;
RECT rc = { 0, 0, 640, 480 };
AdjustWindowRect( &rc, WS_OVERLAPPEDWINDOW, FALSE );
HWND handle = CreateWindow(
L"BTH_GL_DEMO",
L"BTH OpenGL Demo",
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
rc.right - rc.left,
rc.bottom - rc.top,
nullptr,
nullptr,
hInstance,
nullptr);
return handle;
}
LRESULT CALLBACK WndProc( HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam )
{
switch (message)
{
case WM_DESTROY:
PostQuitMessage(0);
break;
}
return DefWindowProc(hWnd, message, wParam, lParam);
}
HGLRC CreateOpenGLContext(HWND wndHandle)
{
//get handle to a device context (DC) for the client area
//of a specified window or for the entire screen
HDC hDC = GetDC(wndHandle);
//details: http://msdn.microsoft.com/en-us/library/windows/desktop/dd318286(v=vs.85).aspx
static PIXELFORMATDESCRIPTOR pixelFormatDesc =
{
sizeof(PIXELFORMATDESCRIPTOR), // size of this pfd
1, // version number
PFD_DRAW_TO_WINDOW | // support window
PFD_SUPPORT_OPENGL | // support OpenGL
PFD_DOUBLEBUFFER | // double buffered
PFD_DEPTH_DONTCARE, // disable depth buffer <-- added by Stefan
PFD_TYPE_RGBA, // RGBA type
32, // 32-bit color depth
0, 0, 0, 0, 0, 0, // color bits ignored
0, // no alpha buffer
0, // shift bit ignored
0, // no accumulation buffer
0, 0, 0, 0, // accum bits ignored
0, // 0-bits for depth buffer <-- modified by Stefan
0, // no stencil buffer
0, // no auxiliary buffer
PFD_MAIN_PLANE, // main layer
0, // reserved
0, 0, 0 // layer masks ignored
};
//attempt to match an appropriate pixel format supported by a
//device context to a given pixel format specification.
int pixelFormat = ChoosePixelFormat(hDC, &pixelFormatDesc);
//set the pixel format of the specified device context
//to the format specified by the iPixelFormat index.
SetPixelFormat(hDC, pixelFormat, &pixelFormatDesc);
//create a new OpenGL rendering context, which is suitable for drawing
//on the device referenced by hdc. The rendering context has the same
//pixel format as the device context.
HGLRC hRC = wglCreateContext(hDC);
//makes a specified OpenGL rendering context the calling thread's current
//rendering context. All subsequent OpenGL calls made by the thread are
//drawn on the device identified by hdc.
wglMakeCurrent(hDC, hRC);
return hRC;
}
这是我的着色器：
顶点着色器（通过）
#version 400
layout(location = 0) in vec3 vertex_position;
layout(location = 1) in vec3 vertex_color;
out vec3 color;
void main() {
color = vertex_color;
gl_Position = vec4(vertex_position, 1.0);
}
几何着色器（冗余，但需要分配）
#version 400
layout(triangles) in;
layout(triangle_strip, max_vertices=3) out;
uniform mat4 MVP;
in vec3 color[];
out vec3 pass_color[];
void main()
{
for(int i=0; i<3; i++)
{
gl_Position = MVP * gl_in[i].gl_Position;
pass_color[i] = color[i];
EmitVertex();
}
EndPrimitive();
}
片段着色器
#version 400
in vec3 pass_color;
out vec4 fragment_color;
void main () {
fragment_color = vec4 (pass_color, 1.0);
}
它的代码量相当大。我会问我的老师，但他周末不在。
如果您需要任何其他信息，请告诉我。
提前致谢！