GLSL-无法从“常量高4-组件VEC4”转换为“缺省出高3-组件VEC3”

Question

我在2GPU.com上学习OpenGL的教程，我被着色器部分卡住了。我在论坛上读过关于这个错误的文章，但我只找到了当人们使用VEC3作为VEC4时出现错误的例子，但我不认为我犯了那个错误，至少不是我设法看到的：

#version 430

void main(void) {
    vec4 vertices[3];
    vertices[0] = vec4( 0.25, -0.25, 0.5, 1.0);
    vertices[1] = vec4(-0.25, -0.25, 0.5, 1.0);
    vertices[2] = vec4( 0.25, 0.25, 0.5, 1.0);

   gl_Position = vertices[gl_VertexID];
}

#version 430

out vec3 color;

void main(void) {
    color = vec4(0.0, 1.0, 0.0, 1.0);
}

Vertex shader failed to compile with the following errors:
ERROR: 0:6: error(#160) Cannot convert from: "const highp 4-component vector of vec4" to: "default out highp 3-component vector of vec3"
ERROR: error(#273) 1 compilation errors.  No code generated


Could not compile shader!

我尝试像这样转换顶点数据：

gl_Position = vec4(vertices[gl_VertexID]);
glPosition = vec3(vertices[glVertexID].xyz); (Incase gl_Position was actually a vec3)

但没有成功。

任何帮助都很感激！

public class ShaderLoader {

public static int createShader(String vertexShaderSource, String fragmentShaderSource) {
    int vertex_shader = loadShader(vertexShaderSource, GL20.GL_VERTEX_SHADER);
    int fragment_shader = loadShader(fragmentShaderSource, GL20.GL_FRAGMENT_SHADER);

    int link_result = 0;

    int programID = GL20.glCreateProgram();
    GL20.glAttachShader(programID, vertex_shader);
    GL20.glAttachShader(programID, fragment_shader);

    GL20.glLinkProgram(programID);
    GL20.glValidateProgram(programID);
    GL20.glGetProgrami(programID, link_result);

    if(link_result == GL11.GL_FALSE) {
        System.out.println("Could not link program!");
        System.exit(0);
    }
    return programID;
}

public static int loadShader(String filename, int type) {
    StringBuilder builder = new StringBuilder();
    try {
        BufferedReader reader = new BufferedReader(new FileReader("src/shaders/" + filename));
        String line;
        while((line = reader.readLine()) != null) {
            builder.append(line).append("\n");
        }
        reader.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

    int shaderID = GL20.glCreateShader(type);
    GL20.glShaderSource(shaderID, builder);
    GL20.glCompileShader(shaderID);
    if(GL20.glGetShaderi(shaderID, GL20.GL_COMPILE_STATUS) == GL11.GL_FALSE) {
        System.out.println(GL20.glGetShaderInfoLog(shaderID, 500));
        System.out.println("Could not compile shader!");
        System.exit(0);
    }
    return shaderID;
}

int shaderProgram = ShaderLoader.createShader("vertexShader.txt", "fragmentShader.txt");

if(type == GL20.GL_VERTEX_SHADER) {
        System.out.println("Vertex: \n" + builder);
    } else if(type == GL20.GL_FRAGMENT_SHADER) {
        System.out.println("Fragment: \n" + builder);
    }

Vertex: 
#version 430

void main(void) {
    vec4 vertices[3];
    vertices[0] = vec4( 0.25, -0.25, 0.5, 1.0);
    vertices[1] = vec4(-0.25, -0.25, 0.5, 1.0);
    vertices[2] = vec4( 0.25, 0.25, 0.5, 1.0);

   gl_Position = vertices[gl_VertexID];
}

Fragment: 
#version 430

out vec4 color;

void main(void) {
    color = vec4(0.0, 1.0, 0.0, 1.0);
}

Answer 1

您错误地使用了getprogrami()函数。第二个参数是告诉函数要返回哪个内部标志的值，在本例中是gl20.link_status。然后将此函数的返回值赋给link_result变量。所以台词：

GL20.glGetProgrami(programID, link_result);

应改为：

link_result = GL20.glGetProgrami(programID, GL20.LINK_STATUS);