OpenGL 纹理呈现黑色，即使它的数据不为空

Question

我已经在 LWJGL OpenGL 中编写了一个可以处理颜色的工作 2D 批处理渲染器。当我向它添加纹理支持时，渲染的四边形始终是黑色的。 STBImage 读取数据就好了。但它仍然呈现黑色。这是着色器：顶点：片段：

#version 450 core

in vec4 v_Colour;
in vec2 v_TexCoord;
in float v_TexIndex;

uniform sampler2D u_TextureSlots[16];

void main() {
    int index = int(v_TexIndex);
    gl_FragColor = texture(u_TextureSlots[index], v_TexCoord) * v_Colour;
}

渲染器的提交方法

public static void Submit(Texture texture, Rect drawRect, Rect uvRect, Vector4f colour) {
    if (hasRoom) {
        texture.BindSlot(textureIndex + 1);
        int index = spriteCount++;
        int offset = index * 6 * VERTEX_COUNT;
        StoreData(offset, textureIndex++, drawRect, uvRect, colour);
        if (textureIndex >= 16) hasRoom = false;
        if (spriteCount >= maxBatchSize) hasRoom = false;
    }
}
private static void StoreData(int offset, int textureIndex, Rect drawRect, Rect uvRect, Vector4f colour) {
    float x1 = drawRect.x;
    float y1 = drawRect.y;
    float x2 = drawRect.x + drawRect.width;
    float y2 = drawRect.y + drawRect.height;
    float u1 = uvRect.x;
    float v1 = uvRect.y;
    float u2 = uvRect.x + uvRect.width;
    float v2 = uvRect.y + uvRect.height;
    for (int vertex = 0; vertex < 6; vertex++) {
        int currentIndex = offset + vertex * VERTEX_COUNT;
        float x = vertex == 0 || vertex == 3 || vertex == 5 ? x1 : x2;
        float y = vertex == 0 || vertex == 3 || vertex == 1 ? y1 : y2;
        float u = x == x1 ? u1 : u2;
        float v = y == y1 ? v1 : v2;
        vertices[currentIndex] = x;
        vertices[currentIndex + 1] = y;
        vertices[currentIndex + 2] = u;
        vertices[currentIndex + 3] = v;
        vertices[currentIndex + 4] = colour.x;
        vertices[currentIndex + 5] = colour.y;
        vertices[currentIndex + 6] = colour.z;
        vertices[currentIndex + 7] = colour.w;
        vertices[currentIndex + 8] = textureIndex;
    }
}

纹理：

public Texture(String filepath) {
        IntBuffer width = BufferUtils.createIntBuffer(1);
        IntBuffer height = BufferUtils.createIntBuffer(1);
        IntBuffer channels = BufferUtils.createIntBuffer(1);

        ByteBuffer data = STBImage.stbi_load(filepath, width, height, channels, 0);
        m_Width = width.get();
        m_Height = height.get();
        m_Channels = channels.get();

        m_RendererID = glCreateTextures(GL_TEXTURE_2D);
        glBindTexture(GL_TEXTURE_2D, m_RendererID);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_Width, m_Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
        glTextureParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTextureParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        assert data != null : "Image " + filepath + " doesn't exist";
        STBImage.stbi_image_free(data);
    }

Answer 1

片段着色器的行为未定义，因为：

int index = int(v_TexIndex);
... u_TextureSlots[index]...;

u_TextureSlots 是采样器数组，v_TexIndex 是片段着色器输入，因此 index 不是 Dynamically uniform expression.
请注意，未定义的行为意味着它可能会起作用，但规范不保证它会起作用。该行为在各种硬件上会有所不同。

查看 GLSL 4.60 版（最新）（来自 OpenGL Shading Language 4.60 Specification - 4.1.7. Opaque Types）：
（当然这条规则也适用于GLSL 4.50版）

When aggregated into arrays within a shader, these types can only be indexed with a dynamically uniform expression, or texture lookup will result in undefined values.

我建议使用 sampler2DArray（参见 Sampler）而不是 sampler2D 的数组。当您使用 sampler2DArray 时，您根本不需要任何索引，因为 "index" 在纹理查找时被编码在纹理坐标的第三个分量中（参见 Texture）。

此外，指定纹理目标并使用glTexParameter

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

或纹理对象并使用glTextureParameteri

glTextureParameteri(m_RendererID, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTextureParameteri(m_RendererID, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

OpenGL 纹理呈现黑色，即使它的数据不为空

OpenGL Texture Renders black eventhough its data is not null

java

opengl

textures

lwjgl