Question

我对opengl es 2相当新，因为我正在编写IOS应用程序，我认为id试试吧！所以我在xcode 4中使用GLKit模板加载了一个默认的opengl程序，在提供的代码中摸索后我开始修改它以便我可以绘制多种不同类型的顶点数组对象......问题只是调用glClearColor似乎产生任何结果 - 整个屏幕现在只是灰色:-( 我不知道出了什么问题，因为我在代码中的关键位置检查了许多glGetError调用，它似乎总是返回0 ...而且，就我的小知识而言，我也遵循绘制所需的步骤VAO自从我最初修改默认代码以显示它工作正常的平面时... 如果你们能帮助新手，我将非常感激！：）

这里是代码的不同相关部分的发布：

//init VAOs:
glGenVertexArraysOES(NUM_VAO, _vertexArrayIDS);
glGenBuffers(NUM_VAO, _vertexBufferIDS);
glGenBuffers(NUM_VAO, _indexBufferIDS);

//init gl object for player:
//setupGLObject(VAO_PLAYER, gCubicVertexData, gCubicIndices, GL_STATIC_DRAW);   
glBindVertexArrayOES(_vertexArrayIDS[VAO_PLAYER]);

glBindBuffer(GL_ARRAY_BUFFER, _vertexBufferIDS[VAO_PLAYER]);
glBufferData(GL_ARRAY_BUFFER, sizeof(gCubicVertexData), gCubicVertexData, GL_STATIC_DRAW);

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _indexBufferIDS[VAO_PLAYER]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(gCubicIndices), gCubicIndices, GL_STATIC_DRAW);

glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(0));
glEnableVertexAttribArray(GLKVertexAttribColor);
glVertexAttribPointer(GLKVertexAttribColor, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(12));
glEnableVertexAttribArray(GLKVertexAttribNormal);
glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(24));

//NSLog(@"glError after player init : %d", glGetError());
//init gl object for player wall:
//setupGLObject(VAO_PWALL, gPlayerWallVertexData, gPlayerWallIndices, GL_DYNAMIC_DRAW);
glBindVertexArrayOES(_vertexArrayIDS[VAO_PWALL]);

glBindBuffer(GL_ARRAY_BUFFER, _vertexBufferIDS[VAO_PWALL]);
glBufferData(GL_ARRAY_BUFFER, sizeof(gPlayerWallVertexData), gPlayerWallVertexData, GL_STATIC_DRAW);

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _indexBufferIDS[VAO_PLAYER]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(gPlayerWallIndices), gPlayerWallIndices, GL_STATIC_DRAW);

glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(0));
glEnableVertexAttribArray(GLKVertexAttribColor);
glVertexAttribPointer(GLKVertexAttribColor, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(12));
glEnableVertexAttribArray(GLKVertexAttribNormal);
glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(24));

//init gl object for wall/floor plane:
//setupGLObject(VAO_WALL_FLOOR_PLANE, gPlanePyVertexData, gPlanePyIndices, GL_STATIC_DRAW);
glBindVertexArrayOES(_vertexArrayIDS[VAO_WALL_FLOOR_PLANE]);

glBindBuffer(GL_ARRAY_BUFFER, _vertexBufferIDS[VAO_WALL_FLOOR_PLANE]);
glBufferData(GL_ARRAY_BUFFER, sizeof(gPlanePyVertexData), gPlanePyVertexData, GL_STATIC_DRAW);

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _indexBufferIDS[VAO_PLAYER]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(gPlanePyIndices), gPlanePyIndices, GL_STATIC_DRAW);

glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(0));
glEnableVertexAttribArray(GLKVertexAttribColor);
glVertexAttribPointer(GLKVertexAttribColor, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(12));
glEnableVertexAttribArray(GLKVertexAttribNormal);
glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), BUFFER_OFFSET(24));

glBindVertexArrayOES(0);

绘图函数 - glkView：（GLKView *）view drawInRect：（CGRect）rect

for (NSString *currentKey in g_renderables) {
    GameObject *currentRenderable = [g_renderables objectForKey:currentKey];

    if (currentRenderable.go_type == LC_FLOOR) {
        glBindVertexArrayOES(_vertexArrayIDS[VAO_WALL_FLOOR_PLANE]);

        glUseProgram(_program);

        glUniformMatrix4fv(uniforms[UNIFORM_MODELVIEWPROJECTION_MATRIX], 1, 0, currentRenderable.go_mvm.m);
        glUniformMatrix3fv(uniforms[UNIFORM_NORMAL_MATRIX], 1, 0, _normalMatrix.m);

        NSLog(@"glError : %d", glGetError());

        glDrawElements(GL_TRIANGLE_STRIP, sizeof(gPlanePyIndices)/sizeof(gPlanePyIndices[0]), GL_UNSIGNED_INT, 0);
    }
    else if (currentRenderable.go_type == LC_WALL) {
        glBindVertexArrayOES(_vertexArrayIDS[VAO_WALL_FLOOR_PLANE]);

        glUseProgram(_program);

        glUniformMatrix4fv(uniforms[UNIFORM_MODELVIEWPROJECTION_MATRIX], 1, 0, currentRenderable.go_mvm.m);
        glUniformMatrix3fv(uniforms[UNIFORM_NORMAL_MATRIX], 1, 0, _normalMatrix.m);

        glDrawElements(GL_TRIANGLE_STRIP, sizeof(gPlanePyIndices)/sizeof(gPlanePyIndices[0]), GL_UNSIGNED_INT, 0);
    }
    else if (currentRenderable.go_type == LC_PLAYER) {
        glBindVertexArrayOES(_vertexArrayIDS[VAO_PLAYER]);

        glUseProgram(_program);

        glUniformMatrix4fv(uniforms[UNIFORM_MODELVIEWPROJECTION_MATRIX], 1, 0, currentRenderable.go_mvm.m);
        glUniformMatrix3fv(uniforms[UNIFORM_NORMAL_MATRIX], 1, 0, _normalMatrix.m);

        glDrawElements(GL_TRIANGLE_STRIP, sizeof(gCubicIndices)/sizeof(gCubicIndices[0]), GL_UNSIGNED_INT, 0);
    }

矩阵计算：

float aspect = fabsf(self.view.bounds.size.width / self.view.bounds.size.height);
GLKMatrix4 projectionMatrix = GLKMatrix4MakePerspective(GLKMathDegreesToRadians(65.0f), aspect, 0.1f, 1000.0f);


for (NSString *currentKey in g_renderables) {
    GLKMatrix4 thisMvm = GLKMatrix4Identity;
    GameObject *currentRenderable = [g_renderables objectForKey:currentKey];

    if (currentRenderable.go_hasVisual) {

        thisMvm = GLKMatrix4Translate(thisMvm, currentRenderable.go_origin.x, currentRenderable.go_origin.y, currentRenderable.go_origin.z);
        if (currentRenderable.go_type == LC_WALL || currentRenderable.go_type == LC_PLAYER) {
            if (currentRenderable.go_type == LC_PLAYER) {
                if (currentRenderable.go_orientation == VV_MINUS_X) {
                    thisMvm = GLKMatrix4RotateY(thisMvm, GLKMathDegreesToRadians(90.0f));
                }
                else if (currentRenderable.go_orientation == VV_PLUS_X) {
                    thisMvm = GLKMatrix4RotateY(thisMvm, GLKMathDegreesToRadians(-90.0f));
                }
                else if (currentRenderable.go_orientation == VV_PLUS_Z) {
                    thisMvm = GLKMatrix4RotateY(thisMvm, GLKMathDegreesToRadians(180.0f));
                }
            }
            else {
                if (currentRenderable.go_orientation == VV_MINUS_X) {
                    thisMvm = GLKMatrix4RotateZ(thisMvm, GLKMathDegreesToRadians(90.0f));
                }
                else if (currentRenderable.go_orientation == VV_PLUS_X) {
                    thisMvm = GLKMatrix4RotateZ(thisMvm, GLKMathDegreesToRadians(-90.0f));
                }
                else if (currentRenderable.go_orientation == VV_PLUS_Z) {
                    thisMvm = GLKMatrix4RotateX(thisMvm, GLKMathDegreesToRadians(-90.0f));
                }
                else if (currentRenderable.go_orientation == VV_MINUS_Z) {
                    thisMvm = GLKMatrix4RotateX(thisMvm, GLKMathDegreesToRadians(90.0f));
                }
            }
        }
        if (currentRenderable.go_type != LC_LINKED_WALL) thisMvm = GLKMatrix4Scale(thisMvm, currentRenderable.width, currentRenderable.height, currentRenderable.depth);
        thisMvm = GLKMatrix4Multiply(GLKMatrix4MakeLookAt(g_currentCam.go_origin.x, g_currentCam.go_origin.y, g_currentCam.go_origin.z, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f), thisMvm);
        //NSLog(@"%f", thisMvm.m[10]);
        thisMvm = GLKMatrix4Multiply(projectionMatrix, thisMvm);

        currentRenderable.go_mvm = thisMvm;

    }
}

就是这样。请帮助!!!

Answer 1

我认为你理解glclearcolor的方式有点混乱。

主要的想法是，对于每一个框架，你应该通过做一个glclear来清除至少颜色位，这就像在你完成绘图后清理一块板。

glclearcolor反而指示OpenGL在清除后应该在整个屏幕上使用哪种颜色。

以下是一个例子：

glClearColor(1.0f,0.0f,0.0f,1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

此示例告诉OpenGL在需要color_buffer_bit的颜色时使用红色。

我希望这会有所帮助。

当使用多个VAO时，opengl es 2仅将屏幕显示为默认颜色值

1 个答案: