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//
// Copyright 2014 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Based on Simple_Texture2D.c from
// Book: OpenGL(R) ES 2.0 Programming Guide
// Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner
// ISBN-10: 0321502795
// ISBN-13: 9780321502797
// Publisher: Addison-Wesley Professional
// URLs: http://safari.informit.com/9780321563835
// http://www.opengles-book.com
#include "SampleApplication.h"
#include "texture_utils.h"
#include "util/shader_utils.h"
class SimpleTexture2DSample : public SampleApplication
{
public:
SimpleTexture2DSample(int argc, char **argv) : SampleApplication("SimpleTexture2D", argc, argv)
{}
bool initialize() override
{
constexpr char kVS[] = R"(attribute vec4 a_position;
attribute vec2 a_texCoord;
varying vec2 v_texCoord;
void main()
{
gl_Position = a_position;
v_texCoord = a_texCoord;
})";
constexpr char kFS[] = R"(precision mediump float;
varying vec2 v_texCoord;
uniform sampler2D s_texture;
void main()
{
gl_FragColor = texture2D(s_texture, v_texCoord);
})";
mProgram = CompileProgram(kVS, kFS);
if (!mProgram)
{
return false;
}
// Get the attribute locations
mPositionLoc = glGetAttribLocation(mProgram, "a_position");
mTexCoordLoc = glGetAttribLocation(mProgram, "a_texCoord");
// Get the sampler location
mSamplerLoc = glGetUniformLocation(mProgram, "s_texture");
// Load the texture
mTexture = CreateSimpleTexture2D();
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
return true;
}
void destroy() override
{
glDeleteProgram(mProgram);
glDeleteTextures(1, &mTexture);
}
void draw() override
{
GLfloat vertices[] = {
-0.5f, 0.5f, 0.0f, // Position 0
0.0f, 0.0f, // TexCoord 0
-0.5f, -0.5f, 0.0f, // Position 1
0.0f, 1.0f, // TexCoord 1
0.5f, -0.5f, 0.0f, // Position 2
1.0f, 1.0f, // TexCoord 2
0.5f, 0.5f, 0.0f, // Position 3
1.0f, 0.0f // TexCoord 3
};
GLushort indices[] = {0, 1, 2, 0, 2, 3};
// Set the viewport
glViewport(0, 0, getWindow()->getWidth(), getWindow()->getHeight());
// Clear the color buffer
glClear(GL_COLOR_BUFFER_BIT);
// Use the program object
glUseProgram(mProgram);
// Load the vertex position
glVertexAttribPointer(mPositionLoc, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), vertices);
// Load the texture coordinate
glVertexAttribPointer(mTexCoordLoc, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat),
vertices + 3);
glEnableVertexAttribArray(mPositionLoc);
glEnableVertexAttribArray(mTexCoordLoc);
// Bind the texture
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, mTexture);
// Set the texture sampler to texture unit to 0
glUniform1i(mSamplerLoc, 0);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);
}
private:
// Handle to a program object
GLuint mProgram;
// Attribute locations
GLint mPositionLoc;
GLint mTexCoordLoc;
// Sampler location
GLint mSamplerLoc;
// Texture handle
GLuint mTexture;
};
int main(int argc, char **argv)
{
SimpleTexture2DSample app(argc, argv);
return app.run();
}
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