Question

我的片段着色器无法正常工作，它只是用白色绘制的。我认为着色器一起不起作用。我尝试多次更改colorO并且没有运气。

#include <glew.h>
#include <glfw3.h>

GLuint compileshaders() {
GLuint vshader, fshader, program;

static const GLchar * vshadersource[] = {
    "#version 450 core                \n"
    " layout (location=0) in vec3 position;\n"
    " layout (location=1) in vec3 color;\n"
    "void main()                  \n"
    "{                                \n"
    "gl_Position = position;          \n"
    "}                                \n"
};

static const GLchar * fshadersource[] = {
    "#version 450 core                \n"
    "out vec4 colorO;                  \n"
    "void main()                  \n"
    "{                                \n"
    " colorO = vec4(1.0,1.0,0.0,1.0);  \n"
    "}                                \n"
};

vshader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vshader, 1, vshadersource, NULL);
glCompileShader(vshader);

fshader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fshader, 1, fshadersource, NULL);
glCompileShader(fshader);

program = glCreateProgram();
glAttachShader(program, vshader);
glAttachShader(program, fshader);
glLinkProgram(program);

glDeleteShader(vshader);
glDeleteShader(fshader);

return program;
}

int main(void)
{
GLFWwindow* window;
GLuint program;
GLuint vertex_array_object;
GLuint buffers[2];

if (!glfwInit())
    return -1;

window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
if (!window)
{
    glfwTerminate();
    return -1;
}

glfwMakeContextCurrent(window);

glewInit();

static const GLfloat positions[] =      {0.25,-0.25,0.5,0.25,0.25,0.5,-0.25,-0.25,0.5};
static const GLfloat colors[] = {1.0,0.0,1.0,1.0};

program = compileshaders();
glUseProgram(program);
glCreateVertexArrays(1, &vertex_array_object);
glCreateBuffers(2, &buffers[0]);
glNamedBufferStorage(buffers[0], sizeof(positions), positions, 0);
glVertexArrayVertexBuffer(vertex_array_object, 0, buffers[0], 0, sizeof(GLfloat) * 3);
glVertexArrayAttribFormat(vertex_array_object, 0, 3, GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribBinding(vertex_array_object, 0, 0);
glEnableVertexArrayAttrib(vertex_array_object, 0);
glNamedBufferStorage(buffers[1], sizeof(colors), colors, 0);
glVertexArrayVertexBuffer(vertex_array_object, 1, buffers[1], 0, sizeof(GLfloat) * 3);
glVertexArrayAttribFormat(vertex_array_object, 1, 3, GL_FLOAT, GL_FALSE, 0);
glVertexArrayAttribBinding(vertex_array_object, 1, 1);
glEnableVertexArrayAttrib(vertex_array_object, 1);
glBindVertexArray(vertex_array_object);


GLfloat clearcolor[4] = { 0.0,0.0,0.4,1.0 };
glPointSize(40);

while (!glfwWindowShouldClose(window))
{
    glClearBufferfv(GL_COLOR, 0, clearcolor);

    glDrawArrays(GL_TRIANGLES, 0, 3);

    glfwSwapBuffers(window);
    glfwPollEvents();
}

glDeleteVertexArrays(1,&vertex_array_object);
glDeleteProgram(program);

glfwTerminate();
return 0;
}

有人可以帮助我吗？我仍然试图掌握opengl。

Answer 1

问题在于您的顶点着色器，您无法直接将position分配给gl_Position，因为position是vec3而gl_Position是{ {1}}。你可以这样做：

vec4

或者您可以将gl_Position = vec4(position, 1.0f);定义为position，即使您的排名为vec4，vec3的最后一个组成部分也会自动设置为position那种情况：

1.0f

您可以在layout (location=0) in vec4 position;调用后检测编译错误，因为您需要以glCompileShader作为第二个参数调用glGetShaderiv，第三个参数是指向结果的变量的指针应该存储。这会给GL_COMPILE_STATUS（0 - 有一些编译错误）或GL_FALSE（1 - 编译成功）。如果出现错误，您可以通过调用GL_TRUE来获取错误日志，您也需要使用glGetShaderInfoLog获取信息日志长度（使用glGetShaderiv作为第二个参数）。您可以对链接器错误执行相同的操作，但是您需要调用GL_INFO_LOG_LENGTH变体而不是glGetProgram*变体。

Answer 2

gl_Position = position;

需要。

gl_Position = vec4(position,1.0);

因为gl_Position是vec4而position是vec3。感谢FamZ帮我发现错误。

Opengl片段着色器仅绘制白色

2 个答案: