삼각형 위에 선을 그립니다.

Question

Xcode에서 새로운 iPhone OpenGL 프로젝트를 만들었습니다. 내 배경을 삼각형으로 채우고 질감을 줬습니다. 아래를 참조하십시오.

CGImageRef spriteImage; 
CGContextRef spriteContext; 
GLubyte *spriteData; 
size_t width, height; 

// Sets up matrices and transforms for OpenGL ES 
glViewport(0, 0, backingWidth, backingHeight); 
glMatrixMode(GL_PROJECTION); 
glLoadIdentity(); 
//glRotatef(-90,0,0,1); 
glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f); 
glMatrixMode(GL_MODELVIEW); 

// Clears the view with black 
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); 

// Sets up pointers and enables states needed for using vertex arrays and textures 
glVertexPointer(2, GL_FLOAT, 0, vertices); 
glEnableClientState(GL_VERTEX_ARRAY); 
//glColorPointer(4, GL_FLOAT, 0, triangleColors); 
//glColor4f(0.0f,1.0f,0.0f,1.0f); 
//glEnableClientState(GL_COLOR_ARRAY); 
glTexCoordPointer(2, GL_FLOAT, 0, spriteTexcoords); 
glEnableClientState(GL_TEXTURE_COORD_ARRAY); 

// Creates a Core Graphics image from an image file 
spriteImage = [UIImage imageNamed:@"Bild.png"].CGImage; 
// Get the width and height of the image 
width = CGImageGetWidth(spriteImage); 
height = CGImageGetHeight(spriteImage); 
// Texture dimensions must be a power of 2. If you write an application that allows users to supply an image, 
// you'll want to add code that checks the dimensions and takes appropriate action if they are not a power of 2. 

if(spriteImage) { 
    // Allocated memory needed for the bitmap context 
    spriteData = (GLubyte *) calloc(width * height * 4, sizeof(GLubyte)); 
    // Uses the bitmap creation function provided by the Core Graphics framework. 
    spriteContext = CGBitmapContextCreate(spriteData, width, height, 8, width * 4, CGImageGetColorSpace(spriteImage), kCGImageAlphaPremultipliedLast); 
    // After you create the context, you can draw the sprite image to the context. 
    CGContextDrawImage(spriteContext, CGRectMake(0.0, 0.0, (CGFloat)width, (CGFloat)height), spriteImage); 
    // You don't need the context at this point, so you need to release it to avoid memory leaks. 
    CGContextRelease(spriteContext); 

    // Use OpenGL ES to generate a name for the texture. 
    glGenTextures(1, &spriteTexture); 
    // Bind the texture name. 
    glBindTexture(GL_TEXTURE_2D, spriteTexture); 
    // Set the texture parameters to use a minifying filter and a linear filer (weighted average) 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 

    // Specify a 2D texture image, providing the a pointer to the image data in memory 
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData); 
    // Release the image data 
    free(spriteData); 

    // Enable use of the texture 
    glEnable(GL_TEXTURE_2D); 
    // Set a blending function to use 
    glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA); 
    // Enable blending 
    glEnable(GL_BLEND); 

나는 두 가지 질문이 있습니다. 나는 OpenGL에 익숙하지 않다.

매개 변수로 두 점을주고 두 점 사이의 선을 삼각형 (배경) 위에 그려야하는 메서드를 작성하고 싶습니다.

 - (void) drawLineFromPoint1:(CGPoint)point1 toPoint2:(CGPoint)point2 { 
GLfloat triangle[] = {   //Just example points 
     0.0f, 0.0f,  
     0.1f, 0.0f, 
     0.1f, 0.0f, 
     0.1f, 0.1f 
    }; 
    GLfloat triangleColors[] = { 
     0.5f, 0.5f, 0.5f, 1.0f 
    }; 
    //now draw the triangle 
} 

그런 것. 지금은이 줄을 지 웁니다 제 2의 방법, (그리고 배경)

내 그리기 방법은 다음과 같습니다 갖고 싶어 : 당신이 전자에게 몇 가지 힌트/도움을 줄 수있는 경우

- (void)drawView 
{ 
    // Make sure that you are drawing to the current context 
    [EAGLContext setCurrentContext:context]; 

    glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer); 
    glClear(GL_COLOR_BUFFER_BIT); 
    glDrawElements(GL_TRIANGLES, number_vertices, GL_UNSIGNED_SHORT, indices); 
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer); 
    [context presentRenderbuffer:GL_RENDERBUFFER_OES]; 

} 

이 좋은 것을, 이동하거나 선을 지울 때마다

환호

Answer 1

기존 접근 방식은 모든을 다시 그려야하는 것입니다.

Answer 2

글쎄, 나는 작동하도록했다. 방금 Vertex-Pointer를 내 삼각형으로 설정하는 것을 놓쳤습니다. 여기가 이제 작동합니다.

- (void)drawView 
    { 

    [EAGLContext setCurrentContext:context]; 

    glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer); 
    glClear(GL_COLOR_BUFFER_BIT); 
    glVertexPointer(2, GL_FLOAT, 0, vertices); 
    glDrawElements(GL_TRIANGLES, number_vertices, GL_UNSIGNED_SHORT, indices); 
    [self drawLines]; 
    glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer); 
    [context presentRenderbuffer:GL_RENDERBUFFER_OES]; 

} 

    - (void) drawLines{ 
    glDisable(GL_TEXTURE_2D); 

    GLfloat points[4]; 
    for (Dataset *data in buttons) { 
     CGPoint s = [data screenPosition]; 
     CGPoint p = [data slot]; 
     points[0] = (GLfloat)(768-s.y); 
     points[1] = (GLfloat)(1024-s.x); 
     points[2] = (GLfloat)(768-p.y); 
     points[3] = (GLfloat)(1024-p.x); 
     glVertexPointer(2, GL_FLOAT, 0, points); 
     glDrawArrays(GL_LINE_STRIP, 0, 2); 

    } 
    glEnable(GL_TEXTURE_2D); 


}