我正在尝试使用我直接从Qt OpenGL示例中获取的一些代码在屏幕上显示某些内容。但是，我无法在屏幕上显示任何内容。所有GL函数似乎都返回正确的值，错误日志不会显示任何问题。调试一个根本不工作的VBO /着色器的最佳方法是什么？
这是我的着色器代码：
QGLShaderProgram* ShaderFactory::buildFlatShader(QObject *parent)
{
string vertSource = string("in vec3 vertex;\n" \
"in vec2 a_texcoord;\n" \
"uniform mat4 objToWorld;\n" \
"uniform mat4 cameraPV;\n" \
"void main() {\n" \
" gl_Position = cameraPV * objToWorld * vec4(vertex,1.0);\n" \
" gl_FrontColor = vec4(a_texcoord.x, 1, 0, 1);\n" \
"}\n");
string fragSource = string("void main() {\n" \
" gl_FragColor = gl_Color;\n" \
"}\n");
QGLShader* vertShader = new QGLShader(QGLShader::Vertex);
vertShader->compileSourceCode(vertSource.c_str());
QGLShader* fragShader = new QGLShader(QGLShader::Fragment);
fragShader->compileSourceCode(fragSource.c_str());
QGLShaderProgram* program = new QGLShaderProgram(parent);
program->addShader(vertShader);
program->addShader(fragShader);
program->link();
cout << program->log().toStdString() << endl;
cout << "Log end--" << endl;
return program;
}
QGLShaderProgram* ShaderFactory::buildShader(QObject *parent)
{
string vertSource = string("in vec3 vertex;\n" \
"in vec3 normal;\n" \
"in vec4 color;\n" \
"varying vec3 worldNormal;\n" \
"varying vec3 worldPos;\n" \
"uniform vec3 cameraPos;\n" \
"uniform mat4 objToWorld;\n" \
"uniform mat4 cameraV;\n" \
"uniform mat4 cameraP;\n" \
"uniform mat4 cameraPV;\n" \
"void main() {\n" \
" gl_Position = cameraPV * objToWorld * vec4(vertex,1.0);\n" \
" gl_FrontColor = color;\n" \
" gl_BackColor = color;\n" \
" worldPos = vertex;\n" \
" worldNormal = normal;\n" \
"}\n");
string fragSource = string("varying vec3 worldNormal;\n" \
"varying vec3 worldPos;\n" \
"uniform vec3 cameraPos;\n" \
"uniform vec3 lightDir;\n" \
"uniform vec4 singleColor;\n" \
"uniform float isSingleColor;\n" \
"void main() {\n" \
" vec3 L = lightDir;\n" \
" vec3 V = normalize(cameraPos - worldPos);\n" \
" vec3 N = normalize(worldNormal);\n" \
" vec3 H = normalize(L+V);\n" \
" vec4 color = isSingleColor*singleColor + (1.0-isSingleColor)*gl_Color;\n" \
" //vec4 color = gl_Color;\n" \
" float amb = .4;\n" \
" vec4 ambient = color * amb;\n" \
" vec4 diffuse = color * (1.0 - amb) * max(dot(L, N), 0.0);\n" \
" vec4 specular = vec4(0);\n" \
" gl_FragColor = vec4(ambient + diffuse + specular);\n" \
"}\n");
QGLShader* vertShader = new QGLShader(QGLShader::Vertex);
vertShader->compileSourceCode(vertSource.c_str());
QGLShader* fragShader = new QGLShader(QGLShader::Fragment);
fragShader->compileSourceCode(fragSource.c_str());
QGLShaderProgram* program = new QGLShaderProgram(parent);
program->addShader(vertShader);
program->addShader(fragShader);
return program;
}
这是我的OpenGL代码
PanelGL::PanelGL() : QGLWidget(PanelGL::defaultFormat())
{
setMouseTracking(true);
_validShaders = false;
camera = new Camera();
if (mainGrid == NULL) {
int range[] = {-10,10};
int numSegments = range[1]-range[0]+1;
QVector<LineSegment> segments(numSegments);
for (int i = 0; i < numSegments; i++) {
segments[i].p1 = Point3(i, 0, 10);
segments[i].p2 = Point3(i, 0, -10);
segments[i].r = 0.4f;
segments[i].g = 0.4f;
segments[i].b = 0.4f;
}
mainGrid = new LineRenderer(segments, 2);
}
}
QGLFormat PanelGL::defaultFormat()
{
QGLFormat format;
//format.setVersion(3,2);
//format.setProfile(QGLFormat::CompatibilityProfile);
return format;
}
bool glewInitialized = false;
void PanelGL::initializeGL()
{
if (!glewInitialized) {
GLenum err = glewInit();
if (GLEW_OK != err)
{
/* Problem: glewInit failed, something is seriously wrong. */
cerr << "Error: " << glewGetErrorString(err) << endl;
}
}
}
void PanelGL::paintGL()
{
glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//glEnable(GL_DEPTH_TEST);
if (!_validShaders) {
_dummyShader = ShaderFactory::buildShader(this);
_flatShader = ShaderFactory::buildFlatShader(this);
_validShaders = true;
}
// render the grid
mainGrid->render(this);
//glDisable(GL_DEPTH_TEST);
}
void PanelGL::resizeGL(int width, int height)
{
glViewport(0,0,width,height);
}
LineRenderer::LineRenderer(QVector<LineSegment> segments, float lineWidth)
{
_validVBOs = FALSE;
//_segments = segments;
_lineWidth = lineWidth;
}
struct VertexData
{
Vector3 position;
Vector2 texCoord;
};
void LineRenderer::render(PanelGL* panel)
{
if (!_validVBOs) {
glGenBuffers(2, _vboIds);
_validVBOs = TRUE;
}
loadVBOs(panel);
Camera* camera = panel->camera;
QMatrix4x4 cameraViewM = Camera::getViewMatrix(camera,panel->width(),panel->height());
QMatrix4x4 cameraProjM = Camera::getProjMatrix(camera,panel->width(),panel->height());
QMatrix4x4 cameraProjViewM = cameraProjM * cameraViewM;
QMatrix4x4 objToWorld;
QGLShaderProgram* flatShader = panel->getFlatShader();
glLineWidth(_lineWidth);
flatShader->bind();
int objToWorldLoc = flatShader->attributeLocation("objToWorld");
flatShader->setUniformValue(objToWorldLoc, objToWorld);
int cameraPVLoc = flatShader->attributeLocation("cameraPV");
flatShader->setUniformValue(cameraPVLoc, cameraProjViewM);
int overrideStrengthLoc = flatShader->attributeLocation("overrideStrength");
flatShader->setUniformValue(overrideStrengthLoc, 0.0f);
// Tell OpenGL which VBOs to use
glBindBuffer(GL_ARRAY_BUFFER, _vboIds[0]);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _vboIds[1]);
// Offset for position
int offset = 0;
// Tell OpenGL programmable pipeline how to locate vertex position data
int vertexLocation = flatShader->attributeLocation("vertex");
flatShader->enableAttributeArray(vertexLocation);
glVertexAttribPointer(vertexLocation, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), (const void *)offset);
// Offset for texture coordinate
offset += sizeof(QVector3D);
// Tell OpenGL programmable pipeline how to locate vertex texture coordinate data
int texcoordLocation = flatShader->attributeLocation("a_texcoord");
flatShader->enableAttributeArray(texcoordLocation);
glVertexAttribPointer(texcoordLocation, 2, GL_FLOAT, GL_FALSE, sizeof(VertexData), (const void *)offset);
// Draw cube geometry using indices from VBO 1
glDrawElements(GL_TRIANGLE_STRIP, 34, GL_UNSIGNED_SHORT, 0);
//drawSegments.call
flatShader->release();
}
void LineRenderer::loadVBOs(PanelGL* panel)
{
VertexData vertices[] = {
// Vertex data for face 0
{QVector3D(-1.0, -1.0, 1.0), QVector2D(0.0, 0.0)}, // v0
{QVector3D( 1.0, -1.0, 1.0), QVector2D(0.33, 0.0)}, // v1
{QVector3D(-1.0, 1.0, 1.0), QVector2D(0.0, 0.5)}, // v2
{QVector3D( 1.0, 1.0, 1.0), QVector2D(0.33, 0.5)}, // v3
// Vertex data for face 1
{QVector3D( 1.0, -1.0, 1.0), QVector2D( 0.0, 0.5)}, // v4
{QVector3D( 1.0, -1.0, -1.0), QVector2D(0.33, 0.5)}, // v5
{QVector3D( 1.0, 1.0, 1.0), QVector2D(0.0, 1.0)}, // v6
{QVector3D( 1.0, 1.0, -1.0), QVector2D(0.33, 1.0)}, // v7
// Vertex data for face 2
{QVector3D( 1.0, -1.0, -1.0), QVector2D(0.66, 0.5)}, // v8
{QVector3D(-1.0, -1.0, -1.0), QVector2D(1.0, 0.5)}, // v9
{QVector3D( 1.0, 1.0, -1.0), QVector2D(0.66, 1.0)}, // v10
{QVector3D(-1.0, 1.0, -1.0), QVector2D(1.0, 1.0)}, // v11
// Vertex data for face 3
{QVector3D(-1.0, -1.0, -1.0), QVector2D(0.66, 0.0)}, // v12
{QVector3D(-1.0, -1.0, 1.0), QVector2D(1.0, 0.0)}, // v13
{QVector3D(-1.0, 1.0, -1.0), QVector2D(0.66, 0.5)}, // v14
{QVector3D(-1.0, 1.0, 1.0), QVector2D(1.0, 0.5)}, // v15
// Vertex data for face 4
{QVector3D(-1.0, -1.0, -1.0), QVector2D(0.33, 0.0)}, // v16
{QVector3D( 1.0, -1.0, -1.0), QVector2D(0.66, 0.0)}, // v17
{QVector3D(-1.0, -1.0, 1.0), QVector2D(0.33, 0.5)}, // v18
{QVector3D( 1.0, -1.0, 1.0), QVector2D(0.66, 0.5)}, // v19
// Vertex data for face 5
{QVector3D(-1.0, 1.0, 1.0), QVector2D(0.33, 0.5)}, // v20
{QVector3D( 1.0, 1.0, 1.0), QVector2D(0.66, 0.5)}, // v21
{QVector3D(-1.0, 1.0, -1.0), QVector2D(0.33, 1.0)}, // v22
{QVector3D( 1.0, 1.0, -1.0), QVector2D(0.66, 1.0)} // v23
};
// Indices for drawing cube faces using triangle strips.
// Triangle strips can be connected by duplicating indices
// between the strips. If connecting strips have opposite
// vertex order then last index of the first strip and first
// index of the second strip needs to be duplicated. If
// connecting strips have same vertex order then only last
// index of the first strip needs to be duplicated.
GLushort indices[] = {
0, 1, 2, 3, 3, // Face 0 - triangle strip ( v0, v1, v2, v3)
4, 4, 5, 6, 7, 7, // Face 1 - triangle strip ( v4, v5, v6, v7)
8, 8, 9, 10, 11, 11, // Face 2 - triangle strip ( v8, v9, v10, v11)
12, 12, 13, 14, 15, 15, // Face 3 - triangle strip (v12, v13, v14, v15)
16, 16, 17, 18, 19, 19, // Face 4 - triangle strip (v16, v17, v18, v19)
20, 20, 21, 22, 23 // Face 5 - triangle strip (v20, v21, v22, v23)
};
// Transfer vertex data to VBO 0
glBindBuffer(GL_ARRAY_BUFFER, _vboIds[0]);
glBufferData(GL_ARRAY_BUFFER, 24 * sizeof(VertexData), vertices, GL_STATIC_DRAW);
// Transfer index data to VBO 1
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _vboIds[1]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 34 * sizeof(GLushort), indices, GL_STATIC_DRAW);
}
答案 0 :(得分：0)
我从一个非常简单的片段着色器（没有顶点着色器）开始，如：
void main()
{
/* Color the fragment red */
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}