OpenGL glm :: translate不会像希望的那样转换矩阵

时间:2018-10-09 13:44:56

标签: c++ opengl matrix transformation glm-math

我需要将多维数据集缩放50倍,并以3.0f单位沿Z轴移动:

glm::mat4 model(1.0f);
model = glm::scale(model, glm::vec3(50.0f, 50.0f, 50.0f));
model = glm::translate(model, glm::vec3(0.0f, 0.0f, 3.0f));

但是结果是我得到了: enter image description here

我期望街区几乎在中心,但事实并非如此。我在做什么错了?
我的顶点着色器:

const char *vertexShaderSource = "#version 330 core\n"
"layout(location = 0) in vec3 aPos;\n"

"uniform mat4 model;\n"
"uniform mat4 view;\n"
"uniform mat4 projection;\n"

"void main()\n"
"{\n"
"   gl_Position = projection * view * model * vec4(aPos, 1.0f);\n"
"}\n\0";

我的视图和投影矩阵:

glm::vec3 cameraPos = glm::vec3(-300.0f, 0.0f, 0.0f);
glm::vec3 cameraFront = glm::vec3(1.0f, 0.0f, 0.0f);
glm::vec3 cameraUp = glm::vec3(0.0f, 1.0f, 0.0f);
glm::mat4 projection = glm::infinitePerspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.001f);
glUniformMatrix4fv(glGetUniformLocation(shaderProgram, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
glm::mat4 view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp);
glUniformMatrix4fv(glGetUniformLocation(shaderProgram, "view"), 1, GL_FALSE, glm::value_ptr(view));

我的数组:

float vertices[] = {
        0.5f,  0.5f, -0.5f,
        0.5f, -0.5f, -0.5f,
        -0.5f, -0.5f, -0.5f,
        -0.5f,  0.5f, -0.5f,
        0.5f,  0.5f, 0.5f,
        0.5f, -0.5f, 0.5f,
        -0.5f, -0.5f, 0.5f,
        -0.5f,  0.5f, 0.5f,
    };
    unsigned int indices[] = {
        0, 1, 2,
        2, 3, 0,
        1, 0, 4,
        1, 4, 5,
        3, 7, 4,
        3, 4, 0,
        6, 2, 1,
        6, 1, 5,
        6, 7, 3,
        6, 3, 2,
        5, 4, 7,
        5, 7, 6,
    };

1 个答案:

答案 0 :(得分:1)

请参阅translate()的glm API文档:

  

构建由3个分量的向量创建的平移4 * 4矩阵。

     

参数

     

m输入矩阵乘以该转换矩阵
  v翻译向量的坐标。

这意味着模型矩阵可以表示为:

model = scale * translate

这将导致翻译乘以比例。注意,必须从左到右“读取”乘法。 (请参见GLSL Programming/Vector and Matrix Operations

交换比例尺和翻译来解决您的问题:

glm::mat4 model(1.0f);
model = glm::translate(model, glm::vec3(0.0f, 0.0f, 3.0f));
model = glm::scale(model, glm::vec3(50.0f, 50.0f, 50.0f));