155 lines
4.7 KiB
C++
155 lines
4.7 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "renderstate/TextureState.h"
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#include "Caches.h"
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#include "utils/TraceUtils.h"
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#include <GLES3/gl3.h>
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#include <memory>
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#include <SkCanvas.h>
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#include <SkBitmap.h>
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namespace android {
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namespace uirenderer {
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// Width of mShadowLutTexture, defines how accurate the shadow alpha lookup table is
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static const int SHADOW_LUT_SIZE = 128;
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// Must define as many texture units as specified by kTextureUnitsCount
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const GLenum kTextureUnits[] = {
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GL_TEXTURE0,
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GL_TEXTURE1,
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GL_TEXTURE2,
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GL_TEXTURE3
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};
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TextureState::TextureState()
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: mTextureUnit(0) {
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glActiveTexture(kTextureUnits[0]);
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resetBoundTextures();
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GLint maxTextureUnits;
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glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &maxTextureUnits);
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LOG_ALWAYS_FATAL_IF(maxTextureUnits < kTextureUnitsCount,
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"At least %d texture units are required!", kTextureUnitsCount);
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glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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}
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TextureState::~TextureState() {
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if (mShadowLutTexture != nullptr) {
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mShadowLutTexture->deleteTexture();
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}
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}
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/**
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* Maps shadow geometry 'alpha' varying (1 for darkest, 0 for transparent) to
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* darkness at that spot. Input values of 0->1 should be mapped within the same
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* range, but can affect the curve for a different visual falloff.
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*
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* This is used to populate the shadow LUT texture for quick lookup in the
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* shadow shader.
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*/
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static float computeShadowOpacity(float ratio) {
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// exponential falloff function provided by UX
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float val = 1 - ratio;
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return exp(-val * val * 4.0) - 0.018;
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}
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void TextureState::constructTexture(Caches& caches) {
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if (mShadowLutTexture == nullptr) {
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mShadowLutTexture.reset(new Texture(caches));
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unsigned char bytes[SHADOW_LUT_SIZE];
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for (int i = 0; i < SHADOW_LUT_SIZE; i++) {
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float inputRatio = i / (SHADOW_LUT_SIZE - 1.0f);
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bytes[i] = computeShadowOpacity(inputRatio) * 255;
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}
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mShadowLutTexture->upload(GL_ALPHA, SHADOW_LUT_SIZE, 1, GL_ALPHA, GL_UNSIGNED_BYTE, &bytes);
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mShadowLutTexture->setFilter(GL_LINEAR);
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mShadowLutTexture->setWrap(GL_CLAMP_TO_EDGE);
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}
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}
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void TextureState::activateTexture(GLuint textureUnit) {
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LOG_ALWAYS_FATAL_IF(textureUnit >= kTextureUnitsCount,
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"Tried to use texture unit index %d, only %d exist",
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textureUnit, kTextureUnitsCount);
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if (mTextureUnit != textureUnit) {
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glActiveTexture(kTextureUnits[textureUnit]);
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mTextureUnit = textureUnit;
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}
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}
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void TextureState::resetActiveTexture() {
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mTextureUnit = -1;
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}
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void TextureState::bindTexture(GLuint texture) {
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if (mBoundTextures[mTextureUnit] != texture) {
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glBindTexture(GL_TEXTURE_2D, texture);
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mBoundTextures[mTextureUnit] = texture;
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}
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}
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void TextureState::bindTexture(GLenum target, GLuint texture) {
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if (target == GL_TEXTURE_2D) {
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bindTexture(texture);
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} else {
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// GLConsumer directly calls glBindTexture() with
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// target=GL_TEXTURE_EXTERNAL_OES, don't cache this target
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// since the cached state could be stale
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glBindTexture(target, texture);
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}
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}
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void TextureState::deleteTexture(GLuint texture) {
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// When glDeleteTextures() is called on a currently bound texture,
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// OpenGL ES specifies that the texture is then considered unbound
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// Consider the following series of calls:
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//
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// glGenTextures -> creates texture name 2
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// glBindTexture(2)
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// glDeleteTextures(2) -> 2 is now unbound
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// glGenTextures -> can return 2 again
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//
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// If we don't call glBindTexture(2) after the second glGenTextures
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// call, any texture operation will be performed on the default
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// texture (name=0)
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unbindTexture(texture);
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glDeleteTextures(1, &texture);
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}
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void TextureState::resetBoundTextures() {
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for (int i = 0; i < kTextureUnitsCount; i++) {
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mBoundTextures[i] = 0;
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}
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}
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void TextureState::unbindTexture(GLuint texture) {
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for (int i = 0; i < kTextureUnitsCount; i++) {
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if (mBoundTextures[i] == texture) {
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mBoundTextures[i] = 0;
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}
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}
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}
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} /* namespace uirenderer */
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} /* namespace android */
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