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//
// Copyright (c) 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 MipMap2D.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 "shader_utils.h"
#include "texture_utils.h"
class MipMap2DSample : public SampleApplication
{
public:
MipMap2DSample(int argc, char **argv) : SampleApplication("MipMap2D", argc, argv) {}
virtual bool initialize()
{
const std::string vs =
R"(uniform float u_offset;
attribute vec4 a_position;
attribute vec2 a_texCoord;
varying vec2 v_texCoord;
void main()
{
gl_Position = a_position;
gl_Position.x += u_offset;
v_texCoord = a_texCoord;
})";
const std::string fs =
R"(precision mediump float;
varying vec2 v_texCoord;
uniform sampler2D s_texture;
void main()
{
gl_FragColor = texture2D(s_texture, v_texCoord);
})";
mProgram = CompileProgram(vs, fs);
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");
// Get the offset location
mOffsetLoc = glGetUniformLocation(mProgram, "u_offset");
// Load the texture
mTextureID = CreateMipMappedTexture2D();
// Check Anisotropy limits
glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &mMaxAnisotropy);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
return true;
}
virtual void destroy()
{
glDeleteProgram(mProgram);
glDeleteTextures(1, &mTextureID);
}
virtual void draw()
{
const GLfloat vertices[] =
{
-0.25f, 0.5f, 0.0f, 5.0f, // Position 0
0.0f, 0.0f, // TexCoord 0
-0.25f, -0.5f, 0.0f, 1.0f, // Position 1
0.0f, 1.0f, // TexCoord 1
0.25f, -0.5f, 0.0f, 1.0f, // Position 2
1.0f, 1.0f, // TexCoord 2
0.25f, 0.5f, 0.0f, 5.0f, // Position 3
1.0f, 0.0f // TexCoord 3
};
const 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, 4, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), vertices);
// Load the texture coordinate
glVertexAttribPointer(mTexCoordLoc, 2, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), vertices + 4);
glEnableVertexAttribArray(mPositionLoc);
glEnableVertexAttribArray(mTexCoordLoc);
// Bind the texture
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, mTextureID);
// Set the sampler texture unit to 0
glUniform1i(mSamplerLoc, 0);
// Draw quad with nearest sampling
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glUniform1f(mOffsetLoc, -0.6f);
glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);
// Draw quad with trilinear filtering
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glUniform1f(mOffsetLoc, 0.0f);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);
// Draw quad with anisotropic filtering
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, mMaxAnisotropy);
glUniform1f(mOffsetLoc, 0.6f);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, 1.0f);
}
private:
// Handle to a program object
GLuint mProgram;
// Attribute locations
GLint mPositionLoc;
GLint mTexCoordLoc;
// Sampler location
GLint mSamplerLoc;
// Offset location
GLint mOffsetLoc;
// Texture handle
GLuint mTextureID;
float mMaxAnisotropy;
};
int main(int argc, char **argv)
{
MipMap2DSample app(argc, argv);
return app.run();
}
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