GLSL 動畫著色器：C 語言 OpenGL 繪製變色移動三角形

編輯：關於C語言

著色器代碼

Vertex Shader (triangle.vert)


#version 400
layout(location = 0) in vec3 vertexPosition;
uniform float loopDuration; // 週期 (秒)
uniform float time;         // 經過時間 (秒)
void main() {
    float timeScale = 2.0 * 3.14159 / loopDuration;
    float currTime = mod(time, loopDuration);
    vec4 offset = vec4(cos(currTime * timeScale) * 0.5,
                       sin(currTime * timeScale) * 0.5,
                       0.0, 0.0);
    gl_Position = vec4(vertexPosition, 1.0) + offset;
}

Fragment Shader (triangle.frag)


#version 400
out vec4 fragColor;
uniform float fragLoopDuration; // 顏色變化週期
uniform float time;
const vec4 colorA = vec4(1.0, 0.0, 0.0, 1.0); // 紅
const vec4 colorB = vec4(0.0, 1.0, 0.0, 1.0); // 綠
void main() {
    float t = mod(time, fragLoopDuration) / fragLoopDuration; // 0~1
    fragColor = mix(colorA, colorB, t); // 線性插值
}

C 主程式關鍵片段


float positionData[] = { 0.8f, 0.0f, 0.0f,  -0.8f, 0.0f, 0.0f,  0.0f, 0.8f, 0.0f };
// 僅位置屬性，顏色由 Fragment Shader 程序產生

GLuint vaoHandle, vboHandle;
GLint timeLoc, loopDurLoc, fragLoopDurLoc;

void initShader() {
    // ... 編譯連結著色器 ...
    glUseProgram(programHandle);
    timeLoc = glGetUniformLocation(programHandle, "time");
    loopDurLoc = glGetUniformLocation(programHandle, "loopDuration");
    fragLoopDurLoc = glGetUniformLocation(programHandle, "fragLoopDuration");
}

void initVBO() {
    glGenVertexArrays(1, &vaoHandle);
    glGenBuffers(1, &vboHandle);
    glBindVertexArray(vaoHandle);
    glBindBuffer(GL_ARRAY_BUFFER, vboHandle);
    glBufferData(GL_ARRAY_BUFFER, sizeof(positionData), positionData, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
}

void render() {
    glClear(GL_COLOR_BUFFER_BIT);
    glBindVertexArray(vaoHandle);

    float t = glutGet(GLUT_ELAPSED_TIME) / 1000.0f; // 秒
    glUniform1f(timeLoc, t);
    glUniform1f(loopDurLoc, 5.0f);       // 位移週期 5 秒
    glUniform1f(fragLoopDurLoc, 10.0f);  // 顏色週期 10 秒

    glDrawArrays(GL_TRIANGLES, 0, 3);
    glBindVertexArray(0);
    glutSwapBuffers();
    glutPostRedisplay();
}