[英]openGL on raspberry pi, indexed vertices
我正在嘗試學習有關樹莓派的一些基本的opengl。 我遵循這些教程https://solarianprogrammer.com/2013/05/13/opengl-101-drawing-primitives/ http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-9-vbo-indexing/
我碰到了我無法解決的prbolem。 我通過在數組中列出頂點成功使它繪制了三角形,然后我嘗試執行相同的操作,但使用索引,它不起作用,我也不知道為什么。 它可以成功編譯並運行,但是不顯示三角形。
這兩個教程都使它變得如此簡單,添加了一個緩沖區並將“ glDrawArrays”替換為“ glDrawElements”。 但我一定錯過了一些東西。
#include <stdio.h>
#include <unistd.h>
#include "../common/startScreen.h"
#include "../common/LoadShaders.h"
// Include GLM
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
using namespace glm;
int main(int argc, const char **argv)
{
float r=0.0;
InitGraphics();
printf("Screen started\n");
// Create and compile our GLSL program from the shaders
GLuint programID = LoadShaders( "simpletransformvertshader.glsl", "simplefragshader.glsl" );
printf("Shaders loaded\n");
// Get a handle for our "MVP" uniform
GLuint MatrixID = glGetUniformLocation(programID, "MVP");
// Get a handle for our buffers
GLuint vertexPosition_modelspaceID = glGetAttribLocation(programID, "vertexPosition_modelspace");
// Projection matrix
glm::mat4 Projection = glm::perspective(45.0f, 16.0f / 9.0f, 0.1f, 100.0f);
// Camera matrix
glm::mat4 View = glm::lookAt(
glm::vec3(0,0,5),
glm::vec3(0,0,0),
glm::vec3(0,1,0),
);
//glm::mat4 myMatrix = glm::translate(10.0f, 0.0f, 0.0f);
// Model matrix : an identity matrix (model will be at the origin)
glm::mat4 Model = glm::mat4(1.0f);
// Our ModelViewProjection : multiplication of our 3 matrices
glm::mat4 MVP = Projection * View * Model; // Remember, matrix$
//glm:mat4 MVP = Prpkection * View * Model;
GLfloat g_vertex_buffer_data[] = {
-1.0f, -1.0f, 0.0f,
1.0f, -1.0f, 0.0f,
1.0f, 1.0f, 0.0f,
// -1.0, 1.0f, 0.0f,
};
GLuint indices[3] = {
0,1,2,
// 2,3,0
};
// Set the viewport
GLuint vertexbuffer;
glGenBuffers(1, &vertexbuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_bu$
GLuint eab;
glGenBuffers(1, &eab);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, eab);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STAT$
do{
// Model = glm::rotate(Model, r, glm::vec3(0.0f, 0.0f, 1.0f));
glClear( GL_COLOR_BUFFER_BIT );
// Use our shader
glUseProgram(programID);
// Send our transformation to the currently bound shader,
// in the "MVP" uniform
glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &MVP[0][0]);
// 1rst attribute buffer : vertices
glEnableVertexAttribArray(vertexPosition_modelspaceID);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glVertexAttribPointer(
vertexPosition_modelspaceID,
3, // size
GL_FLOAT, // type
GL_FALSE, // normalized?
0, // stride
(void*)0 // array buffer offset
);
// see above glEnableVertexAttribArray(vertexPosition_modelspaceID);
// Draw the triangle !
// glDrawArrays(GL_TRIANGLES, 0, 3);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, eab);
glDrawElements( GL_TRIANGLES, 3, GL_UNSIGNED_INT, 0);
glDisableVertexAttribArray(vertexPosition_modelspaceID);
updateScreen();
}
while(1);
// Cleanup VBO
glDeleteBuffers(1, &vertexbuffer);
glDeleteBuffers(1, &eab);
glDeleteProgram(programID);
}
默認情況下,GLES 1.x / 2.x不支持32位索引。 您最多可以使用16位索引,因此應將代碼更改為:
GLushort indices[3] = {...}
[...]
glDrawElements(..., 3, GL_UNSIGNED_SHORT, ...);
請注意,嘗試在不支持GL_OES_element_index_uint
的實現上使用GL_UNSIGNED_INT
作為類型參數,只會導致GL_INVALID_ENUM
錯誤。 您至少應添加一些錯誤檢查以進行調試。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.