基本上，我绘制一个3D立方体，我可以旋转它，但我希望能够触摸它并知道用户触摸的立方体表面的哪个位置。
我正在使用设置，生成和旋转。它基于Molecules代码和NeHe教程＃5。
非常感谢任何帮助，链接，教程和代码。我有很多开发经验，但在openGL和3d方面没什么用。
//
// GLViewController.h
// NeHe Lesson 05
//
// Created by Jeff LaMarche on 12/12/08.
// Copyright Jeff LaMarche Consulting 2008. All rights reserved.
//
#import "GLViewController.h"
#import "GLView.h"
@implementation GLViewController
- (void)drawBox
{
static const GLfloat cubeVertices[] = {
-1.0f, 1.0f, 1.0f,
1.0f, 1.0f, 1.0f,
1.0f,-1.0f, 1.0f,
-1.0f,-1.0f, 1.0f,
-1.0f, 1.0f,-1.0f,
1.0f, 1.0f,-1.0f,
1.0f,-1.0f,-1.0f,
-1.0f,-1.0f,-1.0f
};
static const GLubyte cubeNumberOfIndices = 36;
const GLubyte cubeVertexFaces[] = {
0, 1, 5, // Half of top face
0, 5, 4, // Other half of top face
4, 6, 5, // Half of front face
4, 6, 7, // Other half of front face
0, 1, 2, // Half of back face
0, 3, 2, // Other half of back face
1, 2, 5, // Half of right face
2, 5, 6, // Other half of right face
0, 3, 4, // Half of left face
7, 4, 3, // Other half of left face
3, 6, 2, // Half of bottom face
6, 7, 3, // Other half of bottom face
};
const GLubyte cubeFaceColors[] = {
0, 255, 0, 255,
255, 125, 0, 255,
255, 0, 0, 255,
255, 255, 0, 255,
0, 0, 255, 255,
255, 0, 255, 255
};
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, cubeVertices);
int colorIndex = 0;
for(int i = 0; i < cubeNumberOfIndices; i += 3)
{
glColor4ub(cubeFaceColors[colorIndex], cubeFaceColors[colorIndex+1], cubeFaceColors[colorIndex+2], cubeFaceColors[colorIndex+3]);
int face = (i / 3.0);
if (face%2 != 0.0)
colorIndex+=4;
glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, &cubeVertexFaces[i]);
}
glDisableClientState(GL_VERTEX_ARRAY);
}
//move this to a data model later!
- (GLfixed)floatToFixed:(GLfloat)aValue;
{
return (GLfixed) (aValue * 65536.0f);
}
- (void)drawViewByRotatingAroundX:(float)xRotation rotatingAroundY:(float)yRotation scaling:(float)scaleFactor translationInX:(float)xTranslation translationInY:(float)yTranslation view:(GLView*)view;
{
glMatrixMode(GL_MODELVIEW);
GLfixed currentModelViewMatrix[16] = { 45146, 47441, 2485, 0,
-25149, 26775,-54274, 0,
-40303, 36435, 36650, 0,
0, 0, 0, 65536 };
/*
GLfixed currentModelViewMatrix[16] = { 0, 0, 0, 0,
0, 0, 0, 0,
0, 0, 0, 0,
0, 0, 0, 65536 };
*/
//glLoadIdentity();
//glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -10.0f, 4.0f);
// Reset rotation system
if (isFirstDrawing)
{
//glLoadIdentity();
glMultMatrixx(currentModelViewMatrix);
[self configureLighting];
isFirstDrawing = NO;
}
// Scale the view to fit current multitouch scaling
GLfixed fixedPointScaleFactor = [self floatToFixed:scaleFactor];
glScalex(fixedPointScaleFactor, fixedPointScaleFactor, fixedPointScaleFactor);
// Perform incremental rotation based on current angles in X and Y
glGetFixedv(GL_MODELVIEW_MATRIX, currentModelViewMatrix);
GLfloat totalRotation = sqrt(xRotation*xRotation + yRotation*yRotation);
glRotatex([self floatToFixed:totalRotation],
(GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[1] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[0]),
(GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[5] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[4]),
(GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[9] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[8])
);
// Translate the model by the accumulated amount
glGetFixedv(GL_MODELVIEW_MATRIX, currentModelViewMatrix);
float currentScaleFactor = sqrt(pow((GLfloat)currentModelViewMatrix[0] / 65536.0f, 2.0f) + pow((GLfloat)currentModelViewMatrix[1] / 65536.0f, 2.0f) + pow((GLfloat)currentModelViewMatrix[2] / 65536.0f, 2.0f));
xTranslation = xTranslation / (currentScaleFactor * currentScaleFactor);
yTranslation = yTranslation / (currentScaleFactor * currentScaleFactor);
// Grab the current model matrix, and use the (0,4,8) components to figure the eye's X axis in the model coordinate system, translate along that
glTranslatef(xTranslation * (GLfloat)currentModelViewMatrix[0] / 65536.0f, xTranslation * (GLfloat)currentModelViewMatrix[4] / 65536.0f, xTranslation * (GLfloat)currentModelViewMatrix[8] / 65536.0f);
// Grab the current model matrix, and use the (1,5,9) components to figure the eye's Y axis in the model coordinate system, translate along that
glTranslatef(yTranslation * (GLfloat)currentModelViewMatrix[1] / 65536.0f, yTranslation * (GLfloat)currentModelViewMatrix[5] / 65536.0f, yTranslation * (GLfloat)currentModelViewMatrix[9] / 65536.0f);
// Black background, with depth buffer enabled
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
[self drawBox];
}
- (void)configureLighting;
{
const GLfixed lightAmbient[] = {13107, 13107, 13107, 65535};
const GLfixed lightDiffuse[] = {65535, 65535, 65535, 65535};
const GLfixed matAmbient[] = {65535, 65535, 65535, 65535};
const GLfixed matDiffuse[] = {65535, 65535, 65535, 65535};
const GLfixed lightPosition[] = {30535, -30535, 0, 0};
const GLfixed lightShininess = 20;
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_COLOR_MATERIAL);
glMaterialxv(GL_FRONT_AND_BACK, GL_AMBIENT, matAmbient);
glMaterialxv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiffuse);
glMaterialx(GL_FRONT_AND_BACK, GL_SHININESS, lightShininess);
glLightxv(GL_LIGHT0, GL_AMBIENT, lightAmbient);
glLightxv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse);
glLightxv(GL_LIGHT0, GL_POSITION, lightPosition);
glEnable(GL_DEPTH_TEST);
glShadeModel(GL_SMOOTH);
glEnable(GL_NORMALIZE);
}
-(void)setupView:(GLView*)view
{
const GLfloat zNear = 0.1,
zFar = 1000.0,
fieldOfView = 60.0;
GLfloat size;
glMatrixMode(GL_PROJECTION);
glEnable(GL_DEPTH_TEST);
size = zNear * tanf(DEGREES_TO_RADIANS(fieldOfView) / 2.0);
CGRect rect = view.bounds;
glFrustumf(-size, size, -size / (rect.size.width / rect.size.height), size /
(rect.size.width / rect.size.height), zNear, zFar);
glViewport(0, 0, rect.size.width, rect.size.height);
glScissor(0, 0, rect.size.width, rect.size.height);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glTranslatef(0.0f, 0.0f, -6.0f);
isFirstDrawing = YES;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
}
- (void)dealloc
{
[super dealloc];
}
@end
答案 0 :(得分：1)
为了实现Ray cast命中检查，您应该检查这些来源：
http://www.mvps.org/directx/articles/rayproj.htm
http://bookofhook.com/mousepick.pdf
http://eigenclass.blogspot.com/2008/10/opengl-es-picking-using-ray-boundingbox.html
基本上，首先，从2D触摸创建3D射线。然后使用该光线检查与您的世界中的对象的交叉点。您应该创建当前矩阵的矩阵逆，并使用逆矩阵，使用近和远剪裁平面创建起点和终点位置。然后在计算近点和远点时应该应用投影设置。