所以,我是一个初学图形程序员。我正在做一个摄像头移动的程序。我认为顶点着色器有问题。程序运行没有错误,但屏幕完全空白。这是我正在使用的顶点着色器。
#version 330
in vec4 vPosition;
out vec4 vColor;
uniform mat4 model_view;
uniform mat4 projection;
void main()
{
vec4 pos = projection * model_view * vPosition / vPosition.w;
gl_Position = pos;
vColor = vPosition;
}
如果我把顶点着色器切换回基本版,
#version 330
in vec4 vPosition;
out vec4 vColor;
void
main()
{
gl_Position = vPosition;
vColor = vPosition;
}
程序运行并成功渲染了一个三角形。所以,我很确定错误是出在着色器上。
着色器是在初始化函数中调用的。
void initialize(void)
{
glClearColor(1.0, 1.0, 1.0, 1.0); // white background
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
// Create and initialize a buffer object
GLuint buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(points), points, GL_STATIC_DRAW);
// Load shaders and use the resulting shader program
GLuint program = InitShader("res/shaders/vshader21.glsl", "res/shaders/fshader21.glsl");
model_view = glGetUniformLocation(program, "model_view");
projection = glGetUniformLocation(program, "projection");
glUseProgram(program);
// Initialize the vertex position attribute from the vertex shader
GLuint loc = glGetAttribLocation(program, "vPosition");
glEnableVertexAttribArray(loc);
glVertexAttribPointer(loc, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
}
glBufferData中的 "点数 "如下:
const int WIDTH = 500, HEIGHT = 500;
/* Positions */
vec4 points[] = {
vec4(0.5,0.5, 1, 1),
vec4(-0.5,0.5, 1, 1),
vec4(0.5,-0.5, 1, 1) ,
vec4(-0.5,-0.5, 1, 1)
};
model_view和projection在主应用程序和全局中都是GLuint类型。
我在显示函数中设置了统一的变量(position,model_view)。
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT); // clear the window
glPointSize(20.0);
// Projection transformation parameters
GLfloat left = -1.0, right = 1.0;
GLfloat bottom = -1.0, top = 1.0;
GLfloat zNear = 0, zFar = 3.0;
mat4 p = Ortho(left, right, bottom, top, zNear, zFar);
glUniformMatrix4fv(projection, 1, GL_TRUE, p);
vec4 eye(0.0, 0.0, -1.0, 1.0);
vec4 at(0.0, 0.0, 0.0, 1.0);
vec4 up(0.0, 1.0, 0.0, 0.0);
mat4 mv = LookAt(eye, at, up);
glUniformMatrix4fv(model_view, 1, GL_TRUE, mv);
glDrawArrays(GL_TRIANGLES, 0, 3); // draw the points
glFlush();
}
可能是什么地方出了问题?
显式除法 .w
组件是多余的。
vec4 pos = projection * model_view * vPosition / vPosition.w;
vec4 pos = projection * model_view * vPosition;
请注意 透视鸿沟 是在剪接后自动执行的。
由于向量被乘以右方的统一形式,您不必对矩阵进行转置。
glUniformMatrix4fv(projection, 1, GL_TRUE, p);
glUniformMatrix4fv(projection, 1, GL_FALSE, p);
glUniformMatrix4fv(model_view, 1, GL_TRUE, mv);
glUniformMatrix4fv(model_view, 1, GL_FALSE, mv);