OpenGL為來自一個QVector3D的給定緩沖區的所有頂點著色？

我有一個程式可以渲染 FACET 幾何圖形，然后在相同的 OpenGL 背景關系中在幾何圖形的頂部繪制資料。從定義小平面三角形及其相關顏色的 VBO 按頂點著色時，一切都按預期作業，但是用戶已請求能夠將所有幾何頂點設定為單一顏色（GUI 切換）。

有沒有辦法在不進入并將 VBO 的顏色部分設定為該顏色的情況下執行此操作？看起來效率很低，但我無法從數小時的谷歌搜索中得到任何我嘗試過的東西。

使用 C 、QT6

片段著色器

#version 150 core
#ifdef GL_ES
// Set default precision to medium
precision mediump int;
precision mediump float;
#endif

in vec3 Color;
out vec4 outColor;

void main()
{
    outColor = vec4(Color,1.0f);
}

頂點著色器

#version 150 core
#ifdef GL_ES
// Set default precision to medium
precision mediump int;
precision mediump float;
#endif

uniform mat4 mvp_matrix;
attribute vec4 a_position;
attribute vec2 a_texcoord;
varying vec2 v_texcoord;
attribute vec3 color;
varying vec3 Color;

void main()
{
    Color = color;

    // Calculate vertex position in screen space
    gl_Position = mvp_matrix * a_position;

    // Pass texture coordinate to fragment shader
    // Value will be automatically interpolated to fragments inside polygon faces
    v_texcoord = a_texcoord;
}

相關代碼片段：

// initializing the buffers from vectors of structures
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    // Geometry
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    // Get a copy of the geometry to reference here
    std::vector<storedGeometry::facetData> tGeom = gUseGeom.getGeom();
    // Convert vector to array
    storedGeometry::facetData* aGeom = tGeom.data();

    // Transfer vertex data to VBO 0
    geomBuf.bind();
    geomBuf.allocate(aGeom, int(tGeom.size() * sizeof(storedGeometry::facetData)));

    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    // Currents
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    // Get a copy of the currents data to reference here
    std::vector<storedGeometry::facetData> tCurrents = gUseCurrents.getGeom();
    // Convert vector to array
    storedGeometry::facetData* aCurrent = tCurrents.data();

    // Transfer vertex data to VBO 1
    currentsBuf.bind();
    currentsBuf.allocate(aCurrent, int(tCurrents.size() * sizeof(storedGeometry::facetData)));




// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// drawing 
// Get shader variable locations
    int vertexLocation = program->attributeLocation("a_position");
    int colorLocation = program->attributeLocation("color");
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    // Plot Geometry
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    if (bGeomVisible) {
        geomBuf.bind();
        program->enableAttributeArray(vertexLocation);
        program->setAttributeBuffer(vertexLocation, GL_FLOAT, 0, 3, sizeof(QVector3D));

        program->enableAttributeArray(colorLocation);
        if (bCobbleSolid) { // Solid
// This is what I can't get to work ************************************
            //program->setAttributeValue(colorLocation, 1.0, 1.0, 1.0);
            program->setAttributeValue(colorLocation, QVector3D(1.0,1.0,1.0));
        } else { // Cobble
            program->setAttributeBuffer(colorLocation, GL_FLOAT, 3*sizeof(QVector3D), 3, sizeof(QVector3D));
        }

        // Set polygon/wiremesh or solid/filled mode based on fill/wire toggle
        if (bFillWire) {
            // Polygon = TRUE
            glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
        } else {
            // Filled = FALSE
            glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
        }
        // Draw geometry
        glDrawArrays(GL_TRIANGLES, 0, gUseGeom.gSize() * 6);
    }
    // Debugging
    //out << "gUseGeom.gSize(): " << gUseGeom.gSize() << Qt::endl;
    // Draw cube geometry
    //glDrawElements(GL_TRIANGLES, gUseGeom.gSize() * 3, GL_UNSIGNED_SHORT, 0);
    //glDrawArrays(GL_TRIANGLES, 0, gUseGeom.gSize() * 6);

    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    // Plot Currents
    // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    if (bCurrentsVisible) {
        currentsBuf.bind();
        program->enableAttributeArray(vertexLocation);
        program->setAttributeBuffer(vertexLocation, GL_FLOAT, 0,                   3, sizeof(QVector3D));
        program->enableAttributeArray(colorLocation);
        program->setAttributeBuffer(colorLocation,  GL_FLOAT, 3*sizeof(QVector3D), 3, sizeof(QVector3D));
        glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
        glDrawArrays(GL_TRIANGLES, 0, gUseCurrents.gSize() * 6);
    }

uj5u.com熱心網友回復：

當特定的頂點屬性陣列未啟用（使用glEnableVertexAttribArray）時，所有渲染頂點的該屬性的值取自當前頂點屬性值，如glVertexAttrib函式族所定義。

您忘記禁用頂點屬性陣列，因此不使用當前頂點屬性值。您可以按如下方式修復它：

    if (bCobbleSolid) { // Solid
        program->disableAttributeArray(colorLocation);
        program->setAttributeValue(colorLocation, QVector3D(1.0,1.0,1.0));
    } else { // Cobble
        program->enableAttributeArray(colorLocation);
        program->setAttributeBuffer(colorLocation, GL_FLOAT, 3*sizeof(QVector3D), 3, sizeof(QVector3D));
    }

標籤：C qtopengl

上一篇：保持所有視窗狀態的QML多視窗

下一篇：為什么docker容器不運行？